From 476d818ff8007dd4d99328697f7a1cde294db8ae Mon Sep 17 00:00:00 2001
From: John Favret <64748847+johnfav03@users.noreply.github.com>
Date: Thu, 20 Aug 2026 16:22:27 -0500
Subject: [PATCH 1/6] add diagnostic formatting APIs

---
 packages/typescript/src/api/async/api.ts      | 138 ++++++-
 packages/typescript/src/api/async/types.ts    |   6 +
 packages/typescript/src/api/path.ts           |  39 ++
 .../typescript/src/api/proto.generated.ts     |  23 ++
 packages/typescript/src/api/sync/api.ts       | 134 ++++++-
 packages/typescript/src/api/sync/types.ts     |   6 +
 packages/typescript/test/async/api.test.ts    | 128 +++++++
 packages/typescript/test/sync/api.test.ts     | 120 ++++++
 tsc/internal/api/format_diagnostics.go        | 209 +++++++++++
 tsc/internal/api/proto.go                     | 194 +++++-----
 tsc/internal/api/session.go                   |   4 +
 .../api/session_format_diagnostics_test.go    | 346 ++++++++++++++++++
 .../diagnosticwriter/diagnosticwriter.go      |  29 +-
 .../tsoptions/tsconfigparsing_test.go         |   8 +-
 ...ntMapperDiagnosticDirectives.contentmapper |   5 -
 .../contentMapperDiagnostics.contentmapper    |   2 -
 ...rInvalidDiagnosticDirectives.contentmapper |   4 -
 .../deeplyNestedAssignabilityIssue.errors.txt |  15 +-
 ...uplicateIdentifierRelatedSpans1.errors.txt |  31 +-
 ...uplicateIdentifierRelatedSpans2.errors.txt |  71 ++--
 ...uplicateIdentifierRelatedSpans3.errors.txt |  23 +-
 ...uplicateIdentifierRelatedSpans4.errors.txt |  63 ++--
 ...uplicateIdentifierRelatedSpans5.errors.txt |  23 +-
 ...uplicateIdentifierRelatedSpans6.errors.txt |  23 +-
 ...uplicateIdentifierRelatedSpans7.errors.txt |  71 ++--
 ...opPrettyErrorRelatedInformation.errors.txt |   3 +-
 ...manyCompilerErrorsInTheTwoFiles.errors.txt |  18 -
 .../prettyContextNotDebugAssertion.errors.txt |   3 +-
 .../prettyFileWithErrorsAndTabs.errors.txt    |   2 -
 ....json to typeAcquisition  with json api.js |   2 +-
 ...ypeAcquisition  with jsonSourceFile api.js |   1 -
 ....json to typeAcquisition  with json api.js |   2 +-
 ...ypeAcquisition  with jsonSourceFile api.js |   1 -
 ...rectory with no .ts files with json api.js |   2 +-
 ...th no .ts files with jsonSourceFile api.js |   2 +-
 ...rrors for empty directory with json api.js |   2 +-
 ...empty directory with jsonSourceFile api.js |   2 +-
 ...o references are provided with json api.js |   2 +-
 ...es are provided with jsonSourceFile api.js |   1 -
 ...rors for empty files list with json api.js |   2 +-
 ...mpty files list with jsonSourceFile api.js |   1 -
 ... errors for empty include with json api.js |   2 +-
 ...r empty include with jsonSourceFile api.js |   2 +-
 ... after recursive wildcard with json api.js |   2 +-
 ...ursive wildcard with jsonSourceFile api.js |   3 +-
 ... for includes with outDir with json api.js |   2 +-
 ...des with outDir with jsonSourceFile api.js |   2 +-
 ...ine option is in tsconfig with json api.js |   2 +-
 ... is in tsconfig with jsonSourceFile api.js |   1 -
 ... when files is not string with json api.js |   2 +-
 ...s is not string with jsonSourceFile api.js |   1 -
 ...hen include is not string with json api.js |   2 +-
 ...e is not string with jsonSourceFile api.js |   3 +-
 ...ror for an unknown option with json api.js |   2 +-
 ... unknown option with jsonSourceFile api.js |   1 -
 ...rectly cased option names with json api.js |   2 +-
 ...ed option names with jsonSourceFile api.js |  10 -
 ...on and invalid enum value with json api.js |   2 +-
 ...alid enum value with jsonSourceFile api.js |   3 -
 ...ion for an unknown option with json api.js |   2 +-
 ... unknown option with jsonSourceFile api.js |   1 -
 ...en tsconfig have excludes with json api.js |   2 +-
 ...g have excludes with jsonSourceFile api.js |   1 -
 .../typedefCrossModule5.errors.txt            |  15 +-
 .../tsbuild/commandLine/bad-locale.js         |   1 +
 .../when-build-not-first-argument.js          |   2 +
 .../configFileErrors/missing-config-file.js   |   1 +
 .../when-tsconfig-extends-the-missing-file.js |   4 +
 ...ts-the-error-about-it-by-stopping-build.js |   1 +
 .../noCheck/dts-errors-with-incremental.js    |  18 +-
 .../reference/tsbuild/noCheck/dts-errors.js   |  18 +-
 .../tsbuild/noEmit/changes-composite.js       |  36 +-
 .../noEmit/changes-incremental-declaration.js |  36 +-
 .../tsbuild/noEmit/changes-incremental.js     |  36 +-
 .../changes-with-initial-noEmit-composite.js  |   6 +-
 ...-initial-noEmit-incremental-declaration.js |   6 +-
 ...changes-with-initial-noEmit-incremental.js |   6 +-
 ...ble-changes-with-incremental-as-modules.js |   9 +-
 ...aration-enable-changes-with-incremental.js |   9 +-
 ...tion-enable-changes-with-multiple-files.js |  42 ++-
 ...-errors-with-declaration-enable-changes.js |   9 +-
 .../dts-errors-with-incremental-as-modules.js |  15 +-
 .../noEmit/dts-errors-with-incremental.js     |  15 +-
 .../reference/tsbuild/noEmit/dts-errors.js    |  15 +-
 ...rrors-with-declaration-with-incremental.js |   6 +-
 .../dts-errors-with-declaration.js            |   6 +-
 ...iles-belong-to-rootDir-and-is-composite.js |   3 +
 ...ied-but-not-all-files-belong-to-rootDir.js |   3 +
 ...ting-json-module-from-project-reference.js |   4 +
 ...t-in-not-build-order-doesnt-throw-error.js |   1 +
 ...t-in-not-build-order-doesnt-throw-error.js |   1 +
 ...ror-if-input-file-is-missing-with-force.js |   4 +-
 .../reports-error-if-input-file-is-missing.js |   4 +-
 ...rrors-when-test-does-not-reference-core.js |   6 +-
 ...ects-have-errors-with-stopBuildOnErrors.js |   6 +-
 .../demo/updates-with-circular-reference.js   |   1 +
 .../dts-errors-with-incremental-as-modules.js |  12 +-
 .../noEmit/dts-errors-with-incremental.js     |  12 +-
 .../tsbuildWatch/noEmit/dts-errors.js         |  12 +-
 ...Error-with-declaration-with-incremental.js |   6 +-
 .../noEmitOnError-with-declaration.js         |   6 +-
 ...ceError-when-file-with-no-error-changes.js |   6 +-
 ...ing-errors-only-changed-file-is-emitted.js |   3 +-
 ...tErrors-when-file-with-no-error-changes.js |   6 +-
 ...ixing-error-files-all-files-are-emitted.js |   3 +-
 ...e-down-stream-project-and-then-fixes-it.js |   3 +-
 .../works-with-extended-source-files.js       |   1 +
 .../reexport/Reports-errors-correctly.js      |   3 +-
 ...rrors-when-test-does-not-reference-core.js |   3 +-
 ...ects-have-errors-with-stopBuildOnErrors.js |   3 +-
 ...tches-config-files-that-are-not-present.js |   1 +
 ...ig-with-incorrect-compiler-option-value.js |   1 +
 ...TSConfig-with-incorrect-compiler-option.js |   1 +
 ...Initialized-TSConfig-with-tsconfig.json.js |   1 +
 .../commandLine/Parse-enum-type-options.js    |   1 +
 .../reference/tsc/commandLine/bad-locale.js   |   1 +
 ...nfig-in-different-folder-does-not-exist.js |   1 +
 ...ionless-file-in-tsconfig-does-not-exist.js |   4 +-
 .../extensionless-file-in-tsconfig-exists.js  |   4 +-
 ...tensionless-file-on-command-line-exists.js |   1 +
 .../file-in-tsconfig-does-not-exist.js        |   4 +-
 .../tsc/commandLine/non-object-config-root.js |   1 +
 ...ation-failure-reports-one-project-error.js |   1 +
 ...per-is-disabled-after-repeated-failures.js |   1 +
 ...ist-on-disk-that-differs-only-in-casing.js |   3 +-
 ...m-multiple-places-with-different-casing.js | 133 +++----
 ...ative-and-non-relative-file-resolutions.js |   6 +-
 ...e-with-multiple-files-and-complex-types.js |   3 +-
 ...-config-file-absent-with---ignoreConfig.js |   1 +
 ...oject-and-files-when-config-file-absent.js |   1 +
 ...g-project-and-files-with---ignoreConfig.js |   1 +
 .../ignoreConfig/mixing-project-and-files.js  |   1 +
 .../tsc/ignoreConfig/specifying-files.js      |   1 +
 ...-config-file-absent-with---ignoreConfig.js |   1 +
 ...cifying-project-when-config-file-absent.js |   1 +
 ...mental-with-case-insensitive-file-names.js |   3 +-
 ...ion-field-with-declaration-emit-enabled.js |   6 +-
 .../internal-symbolname-in-tsbuildInfo.js     |  24 +-
 ...th-import-in-jsdoc-in-composite-project.js |   1 +
 .../incremental/serializing-error-chain.js    |   6 +-
 .../libraryResolution/when-noLib-toggles.js   |  10 +
 .../noCheck/dts-errors-with-incremental.js    |  18 +-
 .../reference/tsc/noCheck/dts-errors.js       |  18 +-
 .../reference/tsc/noEmit/changes-composite.js |  36 +-
 .../noEmit/changes-incremental-declaration.js |  36 +-
 .../tsc/noEmit/changes-incremental.js         |  36 +-
 .../changes-with-initial-noEmit-composite.js  |   6 +-
 ...-initial-noEmit-incremental-declaration.js |   6 +-
 ...changes-with-initial-noEmit-incremental.js |   6 +-
 ...tion-enable-changes-with-multiple-files.js |  42 ++-
 .../dts-errors-with-incremental-as-modules.js |  15 +-
 .../tsc/noEmit/dts-errors-with-incremental.js |  15 +-
 .../reference/tsc/noEmit/dts-errors.js        |  15 +-
 ...rrors-with-declaration-with-incremental.js |   6 +-
 .../dts-errors-with-declaration.js            |   6 +-
 .../Default-initialized-TSConfig.js           |   1 +
 .../Show-TSConfig-with-advanced-options.js    |   1 +
 ...fig-with-boolean-value-compiler-options.js |   1 +
 ...Config-with-enum-value-compiler-options.js |   1 +
 ...ig-with-incorrect-compiler-option-value.js |   1 +
 ...TSConfig-with-incorrect-compiler-option.js |   1 +
 ...h-list-compiler-options-with-enum-value.js |   1 +
 ...how-TSConfig-with-list-compiler-options.js |   1 +
 .../parse-tsconfig-with-typeAcquisition.js    |   1 +
 ...sted-subdirectory-removed-and-recreated.js |   3 +-
 .../watch-handles-tsconfig-deleted.js         |   6 +-
 ...-with-tsconfig-files-list-entry-deleted.js |   4 +-
 .../reference/tscWatch/noEmit/dts-errors.js   |  12 +-
 tsc/testdata/submoduleAccepted.txt            |   3 -
 169 files changed, 2078 insertions(+), 680 deletions(-)
 create mode 100644 tsc/internal/api/format_diagnostics.go
 create mode 100644 tsc/internal/api/session_format_diagnostics_test.go

diff --git a/packages/typescript/src/api/async/api.ts b/packages/typescript/src/api/async/api.ts
index 09f38832fe3b3..81c6c5cfcbae6 100644
--- a/packages/typescript/src/api/async/api.ts
+++ b/packages/typescript/src/api/async/api.ts
@@ -44,6 +44,7 @@ import type {
     LSPConnectionOptions,
 } from "../options.ts";
 import {
+    convertToRelativePath,
     createGetCanonicalFileName,
     toPath,
 } from "../path.ts";
@@ -101,6 +102,7 @@ import type {
     EmitOutput,
     EmitOutputFile,
     EmitResult,
+    FormatDiagnosticsHost,
     FreshableType,
     GetImportEditsForSymbolsOptions,
     IdentifierTypePredicate,
@@ -153,6 +155,7 @@ export type {
     EmitOutput,
     EmitOutputFile,
     EmitResult,
+    FormatDiagnosticsHost,
     FreshableType,
     GetImportEditsForSymbolsOptions,
     IdentifierTypePredicate,
@@ -204,6 +207,72 @@ export interface TranspileOutput {
     sourceMapText?: string;
 }
 
+const diagnosticOrigin = globalThis.Symbol("diagnosticOrigin");
+
+interface DiagnosticOrigin {
+    readonly snapshot: number;
+    readonly project: Path;
+}
+
+interface DiagnosticWithOrigin extends Diagnostic {
+    readonly [diagnosticOrigin]?: DiagnosticOrigin;
+}
+
+interface FormatDiagnosticRequest extends Diagnostic {
+    readonly originSnapshot: number;
+    readonly originProject: Path;
+    readonly displayFileName?: string;
+}
+
+function associateDiagnostics(
+    diagnostics: readonly Diagnostic[],
+    origin: DiagnosticOrigin,
+): readonly Diagnostic[] {
+    for (const diagnostic of diagnostics) {
+        Object.defineProperty(diagnostic, diagnosticOrigin, { value: origin });
+        if (diagnostic.messageChain) {
+            associateDiagnostics(diagnostic.messageChain, origin);
+        }
+        if (diagnostic.relatedInformation) {
+            associateDiagnostics(diagnostic.relatedInformation, origin);
+        }
+    }
+    return diagnostics;
+}
+
+function toFormatDiagnosticRequest(
+    diagnostic: Diagnostic,
+    expectedOrigin: DiagnosticOrigin,
+    host: FormatDiagnosticsHost,
+): FormatDiagnosticRequest {
+    const origin = (diagnostic as DiagnosticWithOrigin)[diagnosticOrigin];
+    if (origin?.snapshot !== expectedOrigin.snapshot || origin.project !== expectedOrigin.project) {
+        throw new Error("Diagnostic was not produced by this program.");
+    }
+
+    const { messageChain, relatedInformation, ...diagnosticData } = diagnostic;
+    return {
+        ...diagnosticData,
+        originSnapshot: origin.snapshot,
+        originProject: origin.project,
+        ...(diagnostic.fileName
+            ? {
+                displayFileName: convertToRelativePath(
+                    diagnostic.fileName,
+                    host.getCurrentDirectory(),
+                    fileName => host.getCanonicalFileName(fileName),
+                ),
+            }
+            : {}),
+        ...(messageChain
+            ? { messageChain: messageChain.map(d => toFormatDiagnosticRequest(d, expectedOrigin, host)) }
+            : {}),
+        ...(relatedInformation
+            ? { relatedInformation: relatedInformation.map(d => toFormatDiagnosticRequest(d, expectedOrigin, host)) }
+            : {}),
+    };
+}
+
 export class API<FromLSP extends boolean = false> {
     private client: Client;
     private sourceFileCache: SourceFileCache;
@@ -968,6 +1037,13 @@ export class Program {
         this.toPath = toPath;
     }
 
+    private associateDiagnostics(diagnostics: readonly Diagnostic[]): readonly Diagnostic[] {
+        return associateDiagnostics(diagnostics, {
+            snapshot: this.snapshotId,
+            project: this.project.id,
+        });
+    }
+
     getCompilerOptions(): CompilerOptions {
         return this.project.compilerOptions;
     }
@@ -1104,7 +1180,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return data ?? [];
+        return this.associateDiagnostics(data ?? []);
     }
 
     /**
@@ -1120,7 +1196,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return data ?? [];
+        return this.associateDiagnostics(data ?? []);
     }
 
     /**
@@ -1136,7 +1212,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return data ?? [];
+        return this.associateDiagnostics(data ?? []);
     }
 
     /**
@@ -1152,7 +1228,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return data ?? [];
+        return this.associateDiagnostics(data ?? []);
     }
 
     /**
@@ -1168,7 +1244,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return data ?? [];
+        return this.associateDiagnostics(data ?? []);
     }
 
     /**
@@ -1179,7 +1255,7 @@ export class Program {
             snapshot: this.snapshotId,
             project: this.project.id,
         });
-        return data ?? [];
+        return this.associateDiagnostics(data ?? []);
     }
 
     /**
@@ -1190,7 +1266,7 @@ export class Program {
             snapshot: this.snapshotId,
             project: this.project.id,
         });
-        return data ?? [];
+        return this.associateDiagnostics(data ?? []);
     }
 
     /**
@@ -1201,7 +1277,41 @@ export class Program {
             snapshot: this.snapshotId,
             project: this.project.id,
         });
-        return data ?? [];
+        return this.associateDiagnostics(data ?? []);
+    }
+
+    /**
+     * Formats diagnostics produced by this program.
+     */
+    async formatDiagnostics(
+        diagnostics: readonly Diagnostic[],
+        host: FormatDiagnosticsHost,
+    ): Promise<string> {
+        const origin = { snapshot: this.snapshotId, project: this.project.id };
+        const data = await this.client.apiRequest("formatDiagnostics", {
+            snapshot: this.snapshotId,
+            project: this.project.id,
+            diagnostics: diagnostics.map(d => toFormatDiagnosticRequest(d, origin, host)),
+            newLine: host.getNewLine(),
+        });
+        return data.output;
+    }
+
+    /**
+     * Formats diagnostics produced by this program with color and context.
+     */
+    async formatDiagnosticsWithColorAndContext(
+        diagnostics: readonly Diagnostic[],
+        host: FormatDiagnosticsHost,
+    ): Promise<string> {
+        const origin = { snapshot: this.snapshotId, project: this.project.id };
+        const data = await this.client.apiRequest("formatDiagnosticsWithColorAndContext", {
+            snapshot: this.snapshotId,
+            project: this.project.id,
+            diagnostics: diagnostics.map(d => toFormatDiagnosticRequest(d, origin, host)),
+            newLine: host.getNewLine(),
+        });
+        return data.output;
     }
 
     /**
@@ -1218,7 +1328,7 @@ export class Program {
         });
         return {
             emitSkipped: response.emitSkipped,
-            diagnostics: response.diagnostics,
+            diagnostics: this.associateDiagnostics(response.diagnostics),
             emittedFiles: response.emittedFiles,
         };
     }
@@ -1232,7 +1342,7 @@ export class Program {
             project: this.project.id,
             ...(emitOnly !== undefined ? { emitOnly } : {}),
         });
-        return toEmitOutput(response);
+        return toEmitOutput(response, this.associateDiagnostics(response.diagnostics));
     }
 
     /**
@@ -1244,7 +1354,7 @@ export class Program {
             project: this.project.id,
             files,
         });
-        return toEmitOutput(response);
+        return toEmitOutput(response, this.associateDiagnostics(response.diagnostics));
     }
 
     /**
@@ -1256,18 +1366,18 @@ export class Program {
             project: this.project.id,
             files,
         });
-        return toEmitOutput(response);
+        return toEmitOutput(response, this.associateDiagnostics(response.diagnostics));
     }
 }
 
-function toEmitOutput(response: ProtocolEmitOutputResponse): EmitOutput {
+function toEmitOutput(response: ProtocolEmitOutputResponse, diagnostics: readonly Diagnostic[]): EmitOutput {
     const outputFiles = new Map<string, EmitOutputFile>();
     for (const { fileName, ...outputFile } of response.outputFiles) {
         outputFiles.set(fileName, outputFile);
     }
     return {
         emitSkipped: response.emitSkipped,
-        diagnostics: response.diagnostics,
+        diagnostics,
         outputFiles,
     };
 }
diff --git a/packages/typescript/src/api/async/types.ts b/packages/typescript/src/api/async/types.ts
index adc64768c2452..4446597aa400d 100644
--- a/packages/typescript/src/api/async/types.ts
+++ b/packages/typescript/src/api/async/types.ts
@@ -367,6 +367,12 @@ export interface CompletionInfo {
     readonly entries: readonly CompletionEntry[];
 }
 
+export interface FormatDiagnosticsHost {
+    getCurrentDirectory(): string;
+    getCanonicalFileName(fileName: string): string;
+    getNewLine(): string;
+}
+
 export interface EmitOutputFile {
     readonly text: string;
     readonly sourceFileName?: string | undefined;
diff --git a/packages/typescript/src/api/path.ts b/packages/typescript/src/api/path.ts
index 778cbf8ecedcc..2d30b2a4a49e5 100644
--- a/packages/typescript/src/api/path.ts
+++ b/packages/typescript/src/api/path.ts
@@ -337,6 +337,45 @@ export function isRootedDiskPath(path: string): boolean {
     return getEncodedRootLength(path) > 0;
 }
 
+export function convertToRelativePath(
+    absoluteOrRelativePath: string,
+    basePath: string,
+    getCanonicalFileName: (path: string) => string,
+): string {
+    if (!isRootedDiskPath(absoluteOrRelativePath)) {
+        return absoluteOrRelativePath;
+    }
+
+    const fromComponents = getPathComponents(getNormalizedAbsolutePath(basePath, ""));
+    const toComponents = getPathComponents(getNormalizedAbsolutePath(absoluteOrRelativePath, ""));
+    let start = 0;
+    for (; start < fromComponents.length && start < toComponents.length; start++) {
+        const fromComponent = getCanonicalFileName(fromComponents[start]);
+        const toComponent = getCanonicalFileName(toComponents[start]);
+        const equal = start === 0
+            ? fromComponent.toLowerCase() === toComponent.toLowerCase()
+            : fromComponent === toComponent;
+        if (!equal) {
+            break;
+        }
+    }
+
+    if (start === 0) {
+        return pathFromComponents(toComponents);
+    }
+
+    const relative = Array(fromComponents.length - start).fill("..");
+    return pathFromComponents(["", ...relative, ...toComponents.slice(start)]);
+}
+
+function pathFromComponents(components: readonly string[]): string {
+    if (components.length === 0) {
+        return "";
+    }
+    const root = components[0] && ensureTrailingDirectorySeparator(components[0]);
+    return root + components.slice(1).join(directorySeparator);
+}
+
 /**
  * Converts a file name to a normalized path.
  *
diff --git a/packages/typescript/src/api/proto.generated.ts b/packages/typescript/src/api/proto.generated.ts
index 5e30d12bae247..b05ee9e4e197c 100644
--- a/packages/typescript/src/api/proto.generated.ts
+++ b/packages/typescript/src/api/proto.generated.ts
@@ -124,6 +124,8 @@ export interface APIMethodInfo {
     getProgramDiagnostics: APIMethod<GetProjectDiagnosticsParams, DiagnosticResponse[] | null>;
     getGlobalDiagnostics: APIMethod<GetProjectDiagnosticsParams, DiagnosticResponse[] | null>;
     getConfigFileParsingDiagnostics: APIMethod<GetProjectDiagnosticsParams, DiagnosticResponse[] | null>;
+    formatDiagnostics: APIMethod<FormatDiagnosticsParams, FormatDiagnosticsResponse>;
+    formatDiagnosticsWithColorAndContext: APIMethod<FormatDiagnosticsParams, FormatDiagnosticsResponse>;
     printNode: APIMethod<PrintNodeParams, string>;
     formatNodeForInsertion: APIMethod<FormatNodeForInsertionParams, string>;
     emit: APIMethod<EmitParams, EmitResponse>;
@@ -766,6 +768,8 @@ export interface DiagnosticResponse {
     code: number;
     /** Category is the diagnostic category (error, warning, suggestion, message). */
     category: number;
+    /** Source is a custom diagnostic-code prefix. An empty value uses the default "TS". */
+    source?: string;
     /** Text is the localized diagnostic message text. */
     text: string;
     /** ReportsUnnecessary indicates this diagnostic highlights unnecessary code. */
@@ -776,6 +780,25 @@ export interface DiagnosticResponse {
     messageChain?: DiagnosticResponse[];
     /** RelatedInformation contains related diagnostic information, if any. */
     relatedInformation?: DiagnosticResponse[];
+    /** OriginSnapshot and OriginProject identify the program that produced this diagnostic. */
+    originSnapshot?: number;
+    originProject?: string;
+    /** DisplayFileName is the host-formatted file name used only for diagnostic output. */
+    displayFileName?: string;
+}
+
+/** FormatDiagnosticsParams are parameters for diagnostic formatting methods. */
+export interface FormatDiagnosticsParams {
+    snapshot: number;
+    project: string;
+    diagnostics: readonly DiagnosticResponse[] | null;
+    newLine: string;
+}
+
+/** FormatDiagnosticsResponse is the response for diagnostic formatting methods. */
+export interface FormatDiagnosticsResponse {
+    /** Output is the fully formatted diagnostics text. */
+    output: string;
 }
 
 /** PrintNodeParams are the parameters for the printNode method. */
diff --git a/packages/typescript/src/api/sync/api.ts b/packages/typescript/src/api/sync/api.ts
index 582c0b6c54359..8af6bcb04d71e 100644
--- a/packages/typescript/src/api/sync/api.ts
+++ b/packages/typescript/src/api/sync/api.ts
@@ -52,6 +52,7 @@ import type {
     LSPConnectionOptions,
 } from "../options.ts";
 import {
+    convertToRelativePath,
     createGetCanonicalFileName,
     toPath,
 } from "../path.ts";
@@ -109,6 +110,7 @@ import type {
     EmitOutput,
     EmitOutputFile,
     EmitResult,
+    FormatDiagnosticsHost,
     FreshableType,
     GetImportEditsForSymbolsOptions,
     IdentifierTypePredicate,
@@ -161,6 +163,7 @@ export type {
     EmitOutput,
     EmitOutputFile,
     EmitResult,
+    FormatDiagnosticsHost,
     FreshableType,
     GetImportEditsForSymbolsOptions,
     IdentifierTypePredicate,
@@ -212,6 +215,72 @@ export interface TranspileOutput {
     sourceMapText?: string;
 }
 
+const diagnosticOrigin = globalThis.Symbol("diagnosticOrigin");
+
+interface DiagnosticOrigin {
+    readonly snapshot: number;
+    readonly project: Path;
+}
+
+interface DiagnosticWithOrigin extends Diagnostic {
+    readonly [diagnosticOrigin]?: DiagnosticOrigin;
+}
+
+interface FormatDiagnosticRequest extends Diagnostic {
+    readonly originSnapshot: number;
+    readonly originProject: Path;
+    readonly displayFileName?: string;
+}
+
+function associateDiagnostics(
+    diagnostics: readonly Diagnostic[],
+    origin: DiagnosticOrigin,
+): readonly Diagnostic[] {
+    for (const diagnostic of diagnostics) {
+        Object.defineProperty(diagnostic, diagnosticOrigin, { value: origin });
+        if (diagnostic.messageChain) {
+            associateDiagnostics(diagnostic.messageChain, origin);
+        }
+        if (diagnostic.relatedInformation) {
+            associateDiagnostics(diagnostic.relatedInformation, origin);
+        }
+    }
+    return diagnostics;
+}
+
+function toFormatDiagnosticRequest(
+    diagnostic: Diagnostic,
+    expectedOrigin: DiagnosticOrigin,
+    host: FormatDiagnosticsHost,
+): FormatDiagnosticRequest {
+    const origin = (diagnostic as DiagnosticWithOrigin)[diagnosticOrigin];
+    if (origin?.snapshot !== expectedOrigin.snapshot || origin.project !== expectedOrigin.project) {
+        throw new Error("Diagnostic was not produced by this program.");
+    }
+
+    const { messageChain, relatedInformation, ...diagnosticData } = diagnostic;
+    return {
+        ...diagnosticData,
+        originSnapshot: origin.snapshot,
+        originProject: origin.project,
+        ...(diagnostic.fileName
+            ? {
+                displayFileName: convertToRelativePath(
+                    diagnostic.fileName,
+                    host.getCurrentDirectory(),
+                    fileName => host.getCanonicalFileName(fileName),
+                ),
+            }
+            : {}),
+        ...(messageChain
+            ? { messageChain: messageChain.map(d => toFormatDiagnosticRequest(d, expectedOrigin, host)) }
+            : {}),
+        ...(relatedInformation
+            ? { relatedInformation: relatedInformation.map(d => toFormatDiagnosticRequest(d, expectedOrigin, host)) }
+            : {}),
+    };
+}
+
 export class API<FromLSP extends boolean = false> {
     private client: Client;
     private sourceFileCache: SourceFileCache;
@@ -976,6 +1045,13 @@ export class Program {
         this.toPath = toPath;
     }
 
+    private associateDiagnostics(diagnostics: readonly Diagnostic[]): readonly Diagnostic[] {
+        return associateDiagnostics(diagnostics, {
+            snapshot: this.snapshotId,
+            project: this.project.id,
+        });
+    }
+
     getCompilerOptions(): CompilerOptions {
         return this.project.compilerOptions;
     }
@@ -1112,7 +1188,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return data ?? [];
+        return this.associateDiagnostics(data ?? []);
     }
 
     /**
@@ -1128,7 +1204,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return data ?? [];
+        return this.associateDiagnostics(data ?? []);
     }
 
     /**
@@ -1144,7 +1220,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return data ?? [];
+        return this.associateDiagnostics(data ?? []);
     }
 
     /**
@@ -1160,7 +1236,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return data ?? [];
+        return this.associateDiagnostics(data ?? []);
     }
 
     /**
@@ -1176,7 +1252,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return data ?? [];
+        return this.associateDiagnostics(data ?? []);
     }
 
     /**
@@ -1187,7 +1263,7 @@ export class Program {
             snapshot: this.snapshotId,
             project: this.project.id,
         });
-        return data ?? [];
+        return this.associateDiagnostics(data ?? []);
     }
 
     /**
@@ -1198,7 +1274,7 @@ export class Program {
             snapshot: this.snapshotId,
             project: this.project.id,
         });
-        return data ?? [];
+        return this.associateDiagnostics(data ?? []);
     }
 
     /**
@@ -1209,7 +1285,37 @@ export class Program {
             snapshot: this.snapshotId,
             project: this.project.id,
         });
-        return data ?? [];
+        return this.associateDiagnostics(data ?? []);
+    }
+
+    /** Formats diagnostics produced by this program. */
+    formatDiagnostics(
+        diagnostics: readonly Diagnostic[],
+        host: FormatDiagnosticsHost,
+    ): string {
+        const origin = { snapshot: this.snapshotId, project: this.project.id };
+        const data = this.client.apiRequest("formatDiagnostics", {
+            snapshot: this.snapshotId,
+            project: this.project.id,
+            diagnostics: diagnostics.map(d => toFormatDiagnosticRequest(d, origin, host)),
+            newLine: host.getNewLine(),
+        });
+        return data.output;
+    }
+
+    /** Formats diagnostics produced by this program with color and context. */
+    formatDiagnosticsWithColorAndContext(
+        diagnostics: readonly Diagnostic[],
+        host: FormatDiagnosticsHost,
+    ): string {
+        const origin = { snapshot: this.snapshotId, project: this.project.id };
+        const data = this.client.apiRequest("formatDiagnosticsWithColorAndContext", {
+            snapshot: this.snapshotId,
+            project: this.project.id,
+            diagnostics: diagnostics.map(d => toFormatDiagnosticRequest(d, origin, host)),
+            newLine: host.getNewLine(),
+        });
+        return data.output;
     }
 
     /**
@@ -1226,7 +1332,7 @@ export class Program {
         });
         return {
             emitSkipped: response.emitSkipped,
-            diagnostics: response.diagnostics,
+            diagnostics: this.associateDiagnostics(response.diagnostics),
             emittedFiles: response.emittedFiles,
         };
     }
@@ -1240,7 +1346,7 @@ export class Program {
             project: this.project.id,
             ...(emitOnly !== undefined ? { emitOnly } : {}),
         });
-        return toEmitOutput(response);
+        return toEmitOutput(response, this.associateDiagnostics(response.diagnostics));
     }
 
     /**
@@ -1252,7 +1358,7 @@ export class Program {
             project: this.project.id,
             files,
         });
-        return toEmitOutput(response);
+        return toEmitOutput(response, this.associateDiagnostics(response.diagnostics));
     }
 
     /**
@@ -1264,18 +1370,18 @@ export class Program {
             project: this.project.id,
             files,
         });
-        return toEmitOutput(response);
+        return toEmitOutput(response, this.associateDiagnostics(response.diagnostics));
     }
 }
 
-function toEmitOutput(response: ProtocolEmitOutputResponse): EmitOutput {
+function toEmitOutput(response: ProtocolEmitOutputResponse, diagnostics: readonly Diagnostic[]): EmitOutput {
     const outputFiles = new Map<string, EmitOutputFile>();
     for (const { fileName, ...outputFile } of response.outputFiles) {
         outputFiles.set(fileName, outputFile);
     }
     return {
         emitSkipped: response.emitSkipped,
-        diagnostics: response.diagnostics,
+        diagnostics,
         outputFiles,
     };
 }
diff --git a/packages/typescript/src/api/sync/types.ts b/packages/typescript/src/api/sync/types.ts
index 04e9f3f848577..1173219805f5a 100644
--- a/packages/typescript/src/api/sync/types.ts
+++ b/packages/typescript/src/api/sync/types.ts
@@ -375,6 +375,12 @@ export interface CompletionInfo {
     readonly entries: readonly CompletionEntry[];
 }
 
+export interface FormatDiagnosticsHost {
+    getCurrentDirectory(): string;
+    getCanonicalFileName(fileName: string): string;
+    getNewLine(): string;
+}
+
 export interface EmitOutputFile {
     readonly text: string;
     readonly sourceFileName?: string | undefined;
diff --git a/packages/typescript/test/async/api.test.ts b/packages/typescript/test/async/api.test.ts
index 24ae9c84f1eb8..5cb2a6852a934 100644
--- a/packages/typescript/test/async/api.test.ts
+++ b/packages/typescript/test/async/api.test.ts
@@ -5727,6 +5727,134 @@ describe("Program - diagnostics", () => {
         }
     });
 
+    test("formatDiagnostics and formatDiagnosticsWithColorAndContext", async () => {
+        const source = `const x: number = "oops";\n`;
+        const api = spawnAPI({
+            "/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+            "/src/index.ts": source,
+        });
+        try {
+            const snapshot = await api.updateSnapshot({ openProject: "/tsconfig.json" });
+            const project = snapshot.getProject("/tsconfig.json")!;
+            const diags = await project.program.getSemanticDiagnostics("/src/index.ts");
+            assert.equal(diags.length, 1);
+            const host = {
+                getCurrentDirectory: () => "/SRC",
+                getCanonicalFileName: (fileName: string) => fileName.toLowerCase(),
+                getNewLine: () => "\r\n",
+            };
+
+            const plain = await project.program.formatDiagnostics(diags, host);
+            assert.equal(
+                plain,
+                "index.ts(1,7): error TS2322: Type 'string' is not assignable to type 'number'.\r\n",
+            );
+
+            const color = await project.program.formatDiagnosticsWithColorAndContext(diags, host);
+            assert.ok(color.includes("TS2322: "), color);
+            assert.ok(color.includes(`const x: number = "oops";`), color);
+            assert.ok(color.includes("~"), color);
+            assert.ok(color.includes("\x1b["), color);
+            assert.ok(color.endsWith("\r\n"), color);
+            const doubled = await project.program.formatDiagnosticsWithColorAndContext([diags[0], diags[0]], host);
+            assert.equal(doubled, color + color);
+        }
+        finally {
+            await api.close();
+        }
+    });
+
+    test("formatDiagnostics resolves config-file context", async () => {
+        const config = `{ "compilerOptions": { "target": "invalid" } }`;
+        const api = spawnAPI({
+            "/tsconfig.json": config,
+            "/src/index.ts": `export const x = 1;`,
+        });
+        try {
+            const snapshot = await api.updateSnapshot({ openProject: "/tsconfig.json" });
+            const project = snapshot.getProject("/tsconfig.json")!;
+            const diags = await project.program.getConfigFileParsingDiagnostics();
+            const host = {
+                getCurrentDirectory: () => "/",
+                getCanonicalFileName: (fileName: string) => fileName,
+                getNewLine: () => "\n",
+            };
+
+            const plain = await project.program.formatDiagnostics(diags, host);
+            assert.ok(plain.includes("tsconfig.json(1,34): error TS6046: "), plain);
+
+            const color = await project.program.formatDiagnosticsWithColorAndContext(diags, host);
+            assert.ok(color.includes(`"target": "invalid"`), color);
+        }
+        finally {
+            await api.close();
+        }
+    });
+
+    test("formatDiagnostics rejects diagnostics from another program", async () => {
+        const api = spawnAPI({
+            "/a/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+            "/a/index.ts": `const x: number = "oops";`,
+            "/b/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+            "/b/index.ts": `export const x = 1;`,
+        });
+        try {
+            const snapshot = await api.updateSnapshot({
+                openProjects: ["/a/tsconfig.json", "/b/tsconfig.json"],
+            });
+            const a = snapshot.getProject("/a/tsconfig.json")!.program;
+            const b = snapshot.getProject("/b/tsconfig.json")!.program;
+            const diagnostics = await a.getSemanticDiagnostics("/a/index.ts");
+            const host = {
+                getCurrentDirectory: () => "/",
+                getCanonicalFileName: (fileName: string) => fileName,
+                getNewLine: () => "\n",
+            };
+
+            // @sync: assert.throws(() =>
+            await assert.rejects( // @sync-skip
+                b.formatDiagnostics(diagnostics, host),
+                /Diagnostic was not produced by this program/,
+            );
+        }
+        finally {
+            await api.close();
+        }
+    });
+
+    test("formatDiagnostics rejects diagnostics without origin metadata", async () => {
+        const api = spawnAPI({
+            "/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+            "/src/index.ts": `const x: number = "oops";`,
+        });
+        try {
+            const snapshot = await api.updateSnapshot({ openProject: "/tsconfig.json" });
+            const program = snapshot.getProject("/tsconfig.json")!.program;
+            const diagnostics = await program.getSemanticDiagnostics("/src/index.ts");
+            const host = {
+                getCurrentDirectory: () => "/",
+                getCanonicalFileName: (fileName: string) => fileName,
+                getNewLine: () => "\n",
+            };
+            const diagnosticsWithoutOrigin = [
+                [{ ...diagnostics[0] }],
+                structuredClone(diagnostics),
+                JSON.parse(JSON.stringify(diagnostics)),
+            ];
+
+            for (const clonedDiagnostics of diagnosticsWithoutOrigin) {
+                // @sync: assert.throws(() =>
+                await assert.rejects( // @sync-skip
+                    program.formatDiagnostics(clonedDiagnostics, host),
+                    /Diagnostic was not produced by this program/,
+                );
+            }
+        }
+        finally {
+            await api.close();
+        }
+    });
+
     test("getConfigFileNames and getConfigSourceFile", async () => {
         const baseConfigText = `{ "compilerOptions": { "strict": true } }`;
         const { api, fs } = spawnAPIWithFS({
diff --git a/packages/typescript/test/sync/api.test.ts b/packages/typescript/test/sync/api.test.ts
index 93fe5eae5255f..3553bbf3a221e 100644
--- a/packages/typescript/test/sync/api.test.ts
+++ b/packages/typescript/test/sync/api.test.ts
@@ -5735,6 +5735,126 @@ describe("Program - diagnostics", () => {
         }
     });
 
+    test("formatDiagnostics and formatDiagnosticsWithColorAndContext", () => {
+        const source = `const x: number = "oops";\n`;
+        const api = spawnAPI({
+            "/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+            "/src/index.ts": source,
+        });
+        try {
+            const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
+            const project = snapshot.getProject("/tsconfig.json")!;
+            const diags = project.program.getSemanticDiagnostics("/src/index.ts");
+            assert.equal(diags.length, 1);
+            const host = {
+                getCurrentDirectory: () => "/SRC",
+                getCanonicalFileName: (fileName: string) => fileName.toLowerCase(),
+                getNewLine: () => "\r\n",
+            };
+
+            const plain = project.program.formatDiagnostics(diags, host);
+            assert.equal(
+                plain,
+                "index.ts(1,7): error TS2322: Type 'string' is not assignable to type 'number'.\r\n",
+            );
+
+            const color = project.program.formatDiagnosticsWithColorAndContext(diags, host);
+            assert.ok(color.includes("TS2322: "), color);
+            assert.ok(color.includes(`const x: number = "oops";`), color);
+            assert.ok(color.includes("~"), color);
+            assert.ok(color.includes("\x1b["), color);
+            assert.ok(color.endsWith("\r\n"), color);
+            const doubled = project.program.formatDiagnosticsWithColorAndContext([diags[0], diags[0]], host);
+            assert.equal(doubled, color + color);
+        }
+        finally {
+            api.close();
+        }
+    });
+
+    test("formatDiagnostics resolves config-file context", () => {
+        const config = `{ "compilerOptions": { "target": "invalid" } }`;
+        const api = spawnAPI({
+            "/tsconfig.json": config,
+            "/src/index.ts": `export const x = 1;`,
+        });
+        try {
+            const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
+            const project = snapshot.getProject("/tsconfig.json")!;
+            const diags = project.program.getConfigFileParsingDiagnostics();
+            const host = {
+                getCurrentDirectory: () => "/",
+                getCanonicalFileName: (fileName: string) => fileName,
+                getNewLine: () => "\n",
+            };
+
+            const plain = project.program.formatDiagnostics(diags, host);
+            assert.ok(plain.includes("tsconfig.json(1,34): error TS6046: "), plain);
+
+            const color = project.program.formatDiagnosticsWithColorAndContext(diags, host);
+            assert.ok(color.includes(`"target": "invalid"`), color);
+        }
+        finally {
+            api.close();
+        }
+    });
+
+    test("formatDiagnostics rejects diagnostics from another program", () => {
+        const api = spawnAPI({
+            "/a/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+            "/a/index.ts": `const x: number = "oops";`,
+            "/b/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+            "/b/index.ts": `export const x = 1;`,
+        });
+        try {
+            const snapshot = api.updateSnapshot({
+                openProjects: ["/a/tsconfig.json", "/b/tsconfig.json"],
+            });
+            const a = snapshot.getProject("/a/tsconfig.json")!.program;
+            const b = snapshot.getProject("/b/tsconfig.json")!.program;
+            const diagnostics = a.getSemanticDiagnostics("/a/index.ts");
+            const host = {
+                getCurrentDirectory: () => "/",
+                getCanonicalFileName: (fileName: string) => fileName,
+                getNewLine: () => "\n",
+            };
+
+            assert.throws(() => b.formatDiagnostics(diagnostics, host), /Diagnostic was not produced by this program/);
+        }
+        finally {
+            api.close();
+        }
+    });
+
+    test("formatDiagnostics rejects diagnostics without origin metadata", () => {
+        const api = spawnAPI({
+            "/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+            "/src/index.ts": `const x: number = "oops";`,
+        });
+        try {
+            const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
+            const program = snapshot.getProject("/tsconfig.json")!.program;
+            const diagnostics = program.getSemanticDiagnostics("/src/index.ts");
+            const host = {
+                getCurrentDirectory: () => "/",
+                getCanonicalFileName: (fileName: string) => fileName,
+                getNewLine: () => "\n",
+            };
+            const diagnosticsWithoutOrigin = [
+                [{ ...diagnostics[0] }],
+                structuredClone(diagnostics),
+                JSON.parse(JSON.stringify(diagnostics)),
+            ];
+
+            for (const clonedDiagnostics of diagnosticsWithoutOrigin) {
+                assert.throws(() => program.formatDiagnostics(clonedDiagnostics, host), /Diagnostic was not produced by this program/);
+            }
+        }
+        finally {
+            api.close();
+        }
+    });
+
     test("getConfigFileNames and getConfigSourceFile", () => {
         const baseConfigText = `{ "compilerOptions": { "strict": true } }`;
         const { api, fs } = spawnAPIWithFS({
diff --git a/tsc/internal/api/format_diagnostics.go b/tsc/internal/api/format_diagnostics.go
new file mode 100644
index 0000000000000..83162229983d7
--- /dev/null
+++ b/tsc/internal/api/format_diagnostics.go
@@ -0,0 +1,209 @@
+package api
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/microsoft/TypeScript/tsc/internal/ast"
+	"github.com/microsoft/TypeScript/tsc/internal/compiler"
+	"github.com/microsoft/TypeScript/tsc/internal/diagnostics"
+	"github.com/microsoft/TypeScript/tsc/internal/diagnosticwriter"
+	"github.com/microsoft/TypeScript/tsc/internal/locale"
+	"github.com/microsoft/TypeScript/tsc/internal/tsoptions"
+	"github.com/microsoft/TypeScript/tsc/internal/tspath"
+)
+
+// handleFormatDiagnostics formats diagnostics using source text from their snapshot.
+func (s *Session) handleFormatDiagnostics(ctx context.Context, params *FormatDiagnosticsParams, colorAndContext bool) (*FormatDiagnosticsResponse, error) {
+	sd, err := s.getSnapshotData(params.Snapshot)
+	if err != nil {
+		return nil, err
+	}
+
+	program, err := sd.getProgram(params.Project)
+	if err != nil {
+		return nil, err
+	}
+
+	resolver := newFormatFileResolver(sd, program)
+	diags := make([]diagnosticwriter.Diagnostic, len(params.Diagnostics))
+	for i, d := range params.Diagnostics {
+		diag, err := newWireDiagnostic(d, resolver, params.Snapshot, params.Project)
+		if err != nil {
+			return nil, err
+		}
+		diags[i] = diag
+	}
+
+	formatOpts := &diagnosticwriter.FormattingOptions{
+		NewLine: params.NewLine,
+		ComparePathsOptions: tspath.ComparePathsOptions{
+			CurrentDirectory:          s.projectSession.GetCurrentDirectory(),
+			UseCaseSensitiveFileNames: s.projectSession.FS().UseCaseSensitiveFileNames(),
+		},
+	}
+
+	var sb strings.Builder
+	if colorAndContext {
+		diagnosticwriter.FormatDiagnosticsWithColorAndContext(&sb, diags, formatOpts)
+	} else {
+		diagnosticwriter.WriteFormatDiagnostics(&sb, diags, formatOpts)
+	}
+
+	return &FormatDiagnosticsResponse{Output: sb.String()}, nil
+}
+
+// formatFileResolver resolves source and config files from a snapshot.
+type formatFileResolver struct {
+	sd      *snapshotData
+	program *compiler.Program
+	cache   map[string]*ast.SourceFile
+}
+
+func newFormatFileResolver(sd *snapshotData, program *compiler.Program) *formatFileResolver {
+	return &formatFileResolver{
+		sd:      sd,
+		program: program,
+		cache:   make(map[string]*ast.SourceFile),
+	}
+}
+
+func (r *formatFileResolver) resolve(fileName string) *ast.SourceFile {
+	if fileName == "" {
+		return nil
+	}
+	if file, ok := r.cache[fileName]; ok {
+		return file
+	}
+	file := r.resolveUncached(fileName)
+	r.cache[fileName] = file
+	return file
+}
+
+func (r *formatFileResolver) resolveUncached(fileName string) *ast.SourceFile {
+	if file := r.program.GetSourceFile(fileName); file != nil {
+		return file
+	}
+
+	// Config files are not program source files.
+	commandLine := r.program.CommandLine()
+	if commandLine == nil || commandLine.ConfigFile == nil || commandLine.ConfigFile.SourceFile == nil {
+		return nil
+	}
+
+	requestedPath := tspath.ToPath(fileName, r.program.GetCurrentDirectory(), r.program.UseCaseSensitiveFileNames())
+	if rootConfig := commandLine.ConfigFile.SourceFile; rootConfig.Path() == requestedPath {
+		return rootConfig
+	}
+
+	for _, configFileName := range commandLine.ExtendedSourceFiles() {
+		if tspath.ToPath(configFileName, r.program.GetCurrentDirectory(), r.program.UseCaseSensitiveFileNames()) != requestedPath {
+			continue
+		}
+		configFileContent, ok := r.sd.snapshot.ReadFile(configFileName)
+		if !ok {
+			return nil
+		}
+		return tsoptions.NewTsconfigSourceFileFromFilePath(configFileName, requestedPath, configFileContent).SourceFile
+	}
+
+	return nil
+}
+
+// wireDiagnostic adapts a DiagnosticResponse to diagnosticwriter.Diagnostic.
+type wireDiagnostic struct {
+	resp    *DiagnosticResponse
+	file    diagnosticwriter.FileLike
+	pos     int // UTF-8 byte offset
+	end     int // UTF-8 byte offset
+	chain   []diagnosticwriter.Diagnostic
+	related []diagnosticwriter.Diagnostic
+}
+
+func newWireDiagnostic(
+	resp *DiagnosticResponse,
+	resolver *formatFileResolver,
+	snapshot SnapshotID,
+	project ProjectID,
+) (*wireDiagnostic, error) {
+	if resp.OriginSnapshot != snapshot || resp.OriginProject != project {
+		return nil, fmt.Errorf("%w: diagnostic was not produced by this program", ErrClientError)
+	}
+
+	sourceFile := resolver.resolve(resp.FileName)
+	if resp.FileName != "" && sourceFile == nil {
+		return nil, fmt.Errorf("%w: diagnostic source file not found: %s", ErrClientError, resp.FileName)
+	}
+
+	pos, end := resp.Pos, resp.End
+	var file diagnosticwriter.FileLike
+	if sourceFile != nil {
+		positionMap := sourceFile.GetPositionMap()
+		pos = positionMap.UTF16ToUTF8(resp.Pos)
+		end = positionMap.UTF16ToUTF8(resp.End)
+		textLength := len(sourceFile.Text())
+		pos = max(0, min(pos, textLength))
+		end = max(pos, min(end, textLength))
+		file = sourceFile
+		if resp.DisplayFileName != "" {
+			file = &diagnosticDisplayFile{
+				SourceFile: sourceFile,
+				fileName:   resp.DisplayFileName,
+			}
+		}
+	}
+
+	wd := &wireDiagnostic{resp: resp, file: file, pos: pos, end: end}
+
+	if len(resp.MessageChain) > 0 {
+		wd.chain = make([]diagnosticwriter.Diagnostic, len(resp.MessageChain))
+		for i, c := range resp.MessageChain {
+			diag, err := newWireDiagnostic(c, resolver, snapshot, project)
+			if err != nil {
+				return nil, err
+			}
+			wd.chain[i] = diag
+		}
+	}
+	if len(resp.RelatedInformation) > 0 {
+		wd.related = make([]diagnosticwriter.Diagnostic, len(resp.RelatedInformation))
+		for i, ri := range resp.RelatedInformation {
+			diag, err := newWireDiagnostic(ri, resolver, snapshot, project)
+			if err != nil {
+				return nil, err
+			}
+			wd.related[i] = diag
+		}
+	}
+
+	return wd, nil
+}
+
+type diagnosticDisplayFile struct {
+	*ast.SourceFile
+	fileName string
+}
+
+func (f *diagnosticDisplayFile) FileName() string {
+	return f.fileName
+}
+
+func (f *diagnosticDisplayFile) FileNameIsFormatted() bool {
+	return true
+}
+
+func (d *wireDiagnostic) File() diagnosticwriter.FileLike {
+	return d.file
+}
+
+func (d *wireDiagnostic) Pos() int                        { return d.pos }
+func (d *wireDiagnostic) End() int                        { return d.end }
+func (d *wireDiagnostic) Len() int                        { return d.end - d.pos }
+func (d *wireDiagnostic) Code() int32                     { return d.resp.Code }
+func (d *wireDiagnostic) Category() diagnostics.Category  { return d.resp.Category }
+func (d *wireDiagnostic) Source() string                  { return d.resp.Source }
+func (d *wireDiagnostic) Localize(_ locale.Locale) string { return d.resp.Text }
+
+func (d *wireDiagnostic) MessageChain() []diagnosticwriter.Diagnostic       { return d.chain }
+func (d *wireDiagnostic) RelatedInformation() []diagnosticwriter.Diagnostic { return d.related }
diff --git a/tsc/internal/api/proto.go b/tsc/internal/api/proto.go
index 8178bf0cbef04..74534d56e7507 100644
--- a/tsc/internal/api/proto.go
+++ b/tsc/internal/api/proto.go
@@ -180,14 +180,16 @@ const (
 	MethodGetCompletionsAtPosition Method = "getCompletionsAtPosition"
 
 	// Diagnostic methods
-	MethodGetSyntacticDiagnostics         Method = "getSyntacticDiagnostics"
-	MethodGetBindDiagnostics              Method = "getBindDiagnostics"
-	MethodGetSemanticDiagnostics          Method = "getSemanticDiagnostics"
-	MethodGetSuggestionDiagnostics        Method = "getSuggestionDiagnostics"
-	MethodGetDeclarationDiagnostics       Method = "getDeclarationDiagnostics"
-	MethodGetProgramDiagnostics           Method = "getProgramDiagnostics"
-	MethodGetGlobalDiagnostics            Method = "getGlobalDiagnostics"
-	MethodGetConfigFileParsingDiagnostics Method = "getConfigFileParsingDiagnostics"
+	MethodGetSyntacticDiagnostics              Method = "getSyntacticDiagnostics"
+	MethodGetBindDiagnostics                   Method = "getBindDiagnostics"
+	MethodGetSemanticDiagnostics               Method = "getSemanticDiagnostics"
+	MethodGetSuggestionDiagnostics             Method = "getSuggestionDiagnostics"
+	MethodGetDeclarationDiagnostics            Method = "getDeclarationDiagnostics"
+	MethodGetProgramDiagnostics                Method = "getProgramDiagnostics"
+	MethodGetGlobalDiagnostics                 Method = "getGlobalDiagnostics"
+	MethodGetConfigFileParsingDiagnostics      Method = "getConfigFileParsingDiagnostics"
+	MethodFormatDiagnostics                    Method = "formatDiagnostics"
+	MethodFormatDiagnosticsWithColorAndContext Method = "formatDiagnosticsWithColorAndContext"
 
 	// Emitter methods
 	MethodPrintNode              Method = "printNode"
@@ -465,82 +467,84 @@ var unmarshalers = map[Method]func([]byte) (any, error){
 	MethodGetThisParameterOfSignature:  unmarshallerFor[GetSignaturePropertyParams],
 	MethodGetTargetOfSignature:         unmarshallerFor[GetSignaturePropertyParams],
 
-	MethodGetContextualType:                 unmarshallerFor[GetContextualTypeParams],
-	MethodGetBaseTypeOfLiteralType:          unmarshallerFor[GetBaseTypeOfLiteralTypeParams],
-	MethodGetNonNullableType:                unmarshallerFor[GetTypePropertyParams],
-	MethodGetTypeFromTypeNode:               unmarshallerFor[GetTypeFromTypeNodeParams],
-	MethodGetWidenedType:                    unmarshallerFor[GetWidenedTypeParams],
-	MethodGetParameterType:                  unmarshallerFor[GetParameterTypeParams],
-	MethodGetTypeParameterAtPosition:        unmarshallerFor[GetParameterTypeParams],
-	MethodIsArrayLikeType:                   unmarshallerFor[IsArrayLikeTypeParams],
-	MethodIsTypeAssignableTo:                unmarshallerFor[IsTypeAssignableToParams],
-	MethodGetShorthandAssignmentValueSymbol: unmarshallerFor[GetTypeAtLocationParams],
-	MethodGetTypeOfSymbolAtLocation:         unmarshallerFor[GetTypeOfSymbolAtLocationParams],
-	MethodTypeToTypeNode:                    unmarshallerFor[TypeToTypeNodeParams],
-	MethodSignatureToSignatureDeclaration:   unmarshallerFor[SignatureToSignatureDeclarationParams],
-	MethodTypeToString:                      unmarshallerFor[TypeToTypeNodeParams],
-	MethodIsContextSensitive:                unmarshallerFor[GetContextualTypeParams],
-	MethodGetReturnTypeOfSignature:          unmarshallerFor[GetSignaturePropertyParams],
-	MethodGetRestTypeOfSignature:            unmarshallerFor[CheckerSignatureParams],
-	MethodGetTypePredicateOfSignature:       unmarshallerFor[CheckerSignatureParams],
-	MethodGetBaseTypes:                      unmarshallerFor[CheckerTypeParams],
-	MethodGetPropertiesOfType:               unmarshallerFor[CheckerTypeParams],
-	MethodGetApparentPropertiesOfType:       unmarshallerFor[GetTypePropertyParams],
-	MethodGetApparentType:                   unmarshallerFor[GetTypePropertyParams],
-	MethodGetPropertyOfType:                 unmarshallerFor[GetPropertyOfTypeParams],
-	MethodGetIndexInfosOfType:               unmarshallerFor[CheckerTypeParams],
-	MethodGetConstraintOfTypeParameter:      unmarshallerFor[GetTypePropertyParams],
-	MethodGetBaseConstraintOfType:           unmarshallerFor[CheckerTypeParams],
-	MethodGetDefaultFromTypeParameter:       unmarshallerFor[GetTypePropertyParams],
-	MethodGetTypeArguments:                  unmarshallerFor[CheckerTypeParams],
-	MethodGetImportAdderEdits:               unmarshallerFor[GetImportAdderEditsParams],
-	MethodGetConstantValue:                  unmarshallerFor[CheckerNodeParams],
-	MethodGetSignatureFromDeclaration:       unmarshallerFor[CheckerNodeParams],
-	MethodGetExportSpecifierLocalTarget:     unmarshallerFor[CheckerNodeParams],
-	MethodGetAliasedSymbol:                  unmarshallerFor[CheckerSymbolParams],
-	MethodGetImmediateAliasedSymbol:         unmarshallerFor[CheckerSymbolParams],
-	MethodGetFullyQualifiedName:             unmarshallerFor[CheckerSymbolParams],
-	MethodGetExportsOfModule:                unmarshallerFor[CheckerSymbolParams],
-	MethodGetMemberInModuleExports:          unmarshallerFor[GetMemberInModuleExportsParams],
-	MethodGetJSDocTags:                      unmarshallerFor[CheckerSymbolParams],
-	MethodGetDocumentationComment:           unmarshallerFor[CheckerSymbolParams],
-	MethodIsArrayType:                       unmarshallerFor[CheckerTypeParams],
-	MethodIsTupleType:                       unmarshallerFor[CheckerTypeParams],
-	MethodGetReferencesToSymbolInFile:       unmarshallerFor[GetReferencesToSymbolInFileParams],
-	MethodGetReferencedSymbolsForNode:       unmarshallerFor[GetReferencedSymbolsForNodeParams],
-	MethodGetSignatureUsages:                unmarshallerFor[GetSignatureUsagesParams],
-	MethodGetCompletionsAtPosition:          unmarshallerFor[GetCompletionsAtPositionParams],
-	MethodPrintNode:                         unmarshallerFor[PrintNodeParams],
-	MethodFormatNodeForInsertion:            unmarshallerFor[FormatNodeForInsertionParams],
-	MethodEmit:                              unmarshallerFor[EmitParams],
-	MethodEmitToString:                      unmarshallerFor[EmitParams],
-	MethodGetJavaScriptEmit:                 unmarshallerFor[SelectedFilesEmitParams],
-	MethodGetDeclarationEmit:                unmarshallerFor[SelectedFilesEmitParams],
-	MethodGetAnyType:                        unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetStringType:                     unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetNumberType:                     unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetBooleanType:                    unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetVoidType:                       unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetUndefinedType:                  unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetNullType:                       unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetNeverType:                      unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetUnknownType:                    unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetBigIntType:                     unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetESSymbolType:                   unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetNonPrimitiveType:               unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetWellKnownSymbols:               unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetWellKnownSignatures:            unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetSyntacticDiagnostics:           unmarshallerFor[GetDiagnosticsParams],
-	MethodGetBindDiagnostics:                unmarshallerFor[GetDiagnosticsParams],
-	MethodGetSemanticDiagnostics:            unmarshallerFor[GetDiagnosticsParams],
-	MethodGetSuggestionDiagnostics:          unmarshallerFor[GetDiagnosticsParams],
-	MethodGetDeclarationDiagnostics:         unmarshallerFor[GetDiagnosticsParams],
-	MethodGetProgramDiagnostics:             unmarshallerFor[GetProjectDiagnosticsParams],
-	MethodGetGlobalDiagnostics:              unmarshallerFor[GetProjectDiagnosticsParams],
-	MethodGetConfigFileParsingDiagnostics:   unmarshallerFor[GetProjectDiagnosticsParams],
-	MethodStartCPUProfile:                   unmarshallerFor[ProfileParams],
-	MethodStopCPUProfile:                    noParams,
-	MethodSaveHeapProfile:                   unmarshallerFor[ProfileParams],
+	MethodGetContextualType:                    unmarshallerFor[GetContextualTypeParams],
+	MethodGetBaseTypeOfLiteralType:             unmarshallerFor[GetBaseTypeOfLiteralTypeParams],
+	MethodGetNonNullableType:                   unmarshallerFor[GetTypePropertyParams],
+	MethodGetTypeFromTypeNode:                  unmarshallerFor[GetTypeFromTypeNodeParams],
+	MethodGetWidenedType:                       unmarshallerFor[GetWidenedTypeParams],
+	MethodGetParameterType:                     unmarshallerFor[GetParameterTypeParams],
+	MethodGetTypeParameterAtPosition:           unmarshallerFor[GetParameterTypeParams],
+	MethodIsArrayLikeType:                      unmarshallerFor[IsArrayLikeTypeParams],
+	MethodIsTypeAssignableTo:                   unmarshallerFor[IsTypeAssignableToParams],
+	MethodGetShorthandAssignmentValueSymbol:    unmarshallerFor[GetTypeAtLocationParams],
+	MethodGetTypeOfSymbolAtLocation:            unmarshallerFor[GetTypeOfSymbolAtLocationParams],
+	MethodTypeToTypeNode:                       unmarshallerFor[TypeToTypeNodeParams],
+	MethodSignatureToSignatureDeclaration:      unmarshallerFor[SignatureToSignatureDeclarationParams],
+	MethodTypeToString:                         unmarshallerFor[TypeToTypeNodeParams],
+	MethodIsContextSensitive:                   unmarshallerFor[GetContextualTypeParams],
+	MethodGetReturnTypeOfSignature:             unmarshallerFor[GetSignaturePropertyParams],
+	MethodGetRestTypeOfSignature:               unmarshallerFor[CheckerSignatureParams],
+	MethodGetTypePredicateOfSignature:          unmarshallerFor[CheckerSignatureParams],
+	MethodGetBaseTypes:                         unmarshallerFor[CheckerTypeParams],
+	MethodGetPropertiesOfType:                  unmarshallerFor[CheckerTypeParams],
+	MethodGetApparentPropertiesOfType:          unmarshallerFor[GetTypePropertyParams],
+	MethodGetApparentType:                      unmarshallerFor[GetTypePropertyParams],
+	MethodGetPropertyOfType:                    unmarshallerFor[GetPropertyOfTypeParams],
+	MethodGetIndexInfosOfType:                  unmarshallerFor[CheckerTypeParams],
+	MethodGetConstraintOfTypeParameter:         unmarshallerFor[GetTypePropertyParams],
+	MethodGetBaseConstraintOfType:              unmarshallerFor[CheckerTypeParams],
+	MethodGetDefaultFromTypeParameter:          unmarshallerFor[GetTypePropertyParams],
+	MethodGetTypeArguments:                     unmarshallerFor[CheckerTypeParams],
+	MethodGetImportAdderEdits:                  unmarshallerFor[GetImportAdderEditsParams],
+	MethodGetConstantValue:                     unmarshallerFor[CheckerNodeParams],
+	MethodGetSignatureFromDeclaration:          unmarshallerFor[CheckerNodeParams],
+	MethodGetExportSpecifierLocalTarget:        unmarshallerFor[CheckerNodeParams],
+	MethodGetAliasedSymbol:                     unmarshallerFor[CheckerSymbolParams],
+	MethodGetImmediateAliasedSymbol:            unmarshallerFor[CheckerSymbolParams],
+	MethodGetFullyQualifiedName:                unmarshallerFor[CheckerSymbolParams],
+	MethodGetExportsOfModule:                   unmarshallerFor[CheckerSymbolParams],
+	MethodGetMemberInModuleExports:             unmarshallerFor[GetMemberInModuleExportsParams],
+	MethodGetJSDocTags:                         unmarshallerFor[CheckerSymbolParams],
+	MethodGetDocumentationComment:              unmarshallerFor[CheckerSymbolParams],
+	MethodIsArrayType:                          unmarshallerFor[CheckerTypeParams],
+	MethodIsTupleType:                          unmarshallerFor[CheckerTypeParams],
+	MethodGetReferencesToSymbolInFile:          unmarshallerFor[GetReferencesToSymbolInFileParams],
+	MethodGetReferencedSymbolsForNode:          unmarshallerFor[GetReferencedSymbolsForNodeParams],
+	MethodGetSignatureUsages:                   unmarshallerFor[GetSignatureUsagesParams],
+	MethodGetCompletionsAtPosition:             unmarshallerFor[GetCompletionsAtPositionParams],
+	MethodPrintNode:                            unmarshallerFor[PrintNodeParams],
+	MethodFormatNodeForInsertion:               unmarshallerFor[FormatNodeForInsertionParams],
+	MethodEmit:                                 unmarshallerFor[EmitParams],
+	MethodEmitToString:                         unmarshallerFor[EmitParams],
+	MethodGetJavaScriptEmit:                    unmarshallerFor[SelectedFilesEmitParams],
+	MethodGetDeclarationEmit:                   unmarshallerFor[SelectedFilesEmitParams],
+	MethodGetAnyType:                           unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetStringType:                        unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetNumberType:                        unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetBooleanType:                       unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetVoidType:                          unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetUndefinedType:                     unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetNullType:                          unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetNeverType:                         unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetUnknownType:                       unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetBigIntType:                        unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetESSymbolType:                      unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetNonPrimitiveType:                  unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetWellKnownSymbols:                  unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetWellKnownSignatures:               unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetSyntacticDiagnostics:              unmarshallerFor[GetDiagnosticsParams],
+	MethodGetBindDiagnostics:                   unmarshallerFor[GetDiagnosticsParams],
+	MethodGetSemanticDiagnostics:               unmarshallerFor[GetDiagnosticsParams],
+	MethodGetSuggestionDiagnostics:             unmarshallerFor[GetDiagnosticsParams],
+	MethodGetDeclarationDiagnostics:            unmarshallerFor[GetDiagnosticsParams],
+	MethodGetProgramDiagnostics:                unmarshallerFor[GetProjectDiagnosticsParams],
+	MethodGetGlobalDiagnostics:                 unmarshallerFor[GetProjectDiagnosticsParams],
+	MethodGetConfigFileParsingDiagnostics:      unmarshallerFor[GetProjectDiagnosticsParams],
+	MethodFormatDiagnostics:                    unmarshallerFor[FormatDiagnosticsParams],
+	MethodFormatDiagnosticsWithColorAndContext: unmarshallerFor[FormatDiagnosticsParams],
+	MethodStartCPUProfile:                      unmarshallerFor[ProfileParams],
+	MethodStopCPUProfile:                       noParams,
+	MethodSaveHeapProfile:                      unmarshallerFor[ProfileParams],
 }
 
 type ParseConfigFileParams struct {
@@ -1421,6 +1425,8 @@ type DiagnosticResponse struct {
 	Code int32 `json:"code"`
 	// Category is the diagnostic category (error, warning, suggestion, message).
 	Category diagnostics.Category `json:"category"`
+	// Source is a custom diagnostic-code prefix. An empty value uses the default "TS".
+	Source string `json:"source,omitempty"`
 	// Text is the localized diagnostic message text.
 	Text string `json:"text"`
 	// ReportsUnnecessary indicates this diagnostic highlights unnecessary code.
@@ -1431,6 +1437,11 @@ type DiagnosticResponse struct {
 	MessageChain []*DiagnosticResponse `json:"messageChain,omitempty"`
 	// RelatedInformation contains related diagnostic information, if any.
 	RelatedInformation []*DiagnosticResponse `json:"relatedInformation,omitempty"`
+	// OriginSnapshot and OriginProject identify the program that produced this diagnostic.
+	OriginSnapshot SnapshotID `json:"originSnapshot,omitzero"`
+	OriginProject  ProjectID  `json:"originProject,omitzero"`
+	// DisplayFileName is the host-formatted file name used only for diagnostic output.
+	DisplayFileName string `json:"displayFileName,omitempty"`
 }
 
 // NewDiagnosticResponse converts an ast.Diagnostic to a DiagnosticResponse.
@@ -1448,6 +1459,7 @@ func NewDiagnosticResponse(d *ast.Diagnostic) *DiagnosticResponse {
 		End:                end,
 		Code:               d.Code(),
 		Category:           d.Category(),
+		Source:             d.Source(),
 		Text:               d.Localize(locale.Default),
 		ReportsUnnecessary: d.ReportsUnnecessary(),
 		ReportsDeprecated:  d.ReportsDeprecated(),
@@ -1486,6 +1498,20 @@ func NewDiagnosticResponses(diags []*ast.Diagnostic) []*DiagnosticResponse {
 	return result
 }
 
+// FormatDiagnosticsParams are parameters for diagnostic formatting methods.
+type FormatDiagnosticsParams struct {
+	Snapshot    SnapshotID            `json:"snapshot"`
+	Project     ProjectID             `json:"project"`
+	Diagnostics []*DiagnosticResponse `json:"diagnostics"`
+	NewLine     string                `json:"newLine"`
+}
+
+// FormatDiagnosticsResponse is the response for diagnostic formatting methods.
+type FormatDiagnosticsResponse struct {
+	// Output is the fully formatted diagnostics text.
+	Output string `json:"output"`
+}
+
 func unmarshalPayload(method string, payload json.Value) (any, error) {
 	unmarshaler, ok := unmarshalers[Method(method)]
 	if !ok {
diff --git a/tsc/internal/api/session.go b/tsc/internal/api/session.go
index e87e02c9b7ca3..384cab2fa039c 100644
--- a/tsc/internal/api/session.go
+++ b/tsc/internal/api/session.go
@@ -859,6 +859,10 @@ func (s *Session) HandleRequest(ctx context.Context, method string, params json.
 		return s.handleGetGlobalDiagnostics(ctx, parsed.(*GetProjectDiagnosticsParams))
 	case string(MethodGetConfigFileParsingDiagnostics):
 		return s.handleGetConfigFileParsingDiagnostics(ctx, parsed.(*GetProjectDiagnosticsParams))
+	case string(MethodFormatDiagnostics):
+		return s.handleFormatDiagnostics(ctx, parsed.(*FormatDiagnosticsParams), false /*colorAndContext*/)
+	case string(MethodFormatDiagnosticsWithColorAndContext):
+		return s.handleFormatDiagnostics(ctx, parsed.(*FormatDiagnosticsParams), true /*colorAndContext*/)
 	case string(MethodStartCPUProfile):
 		return s.handleStartCPUProfile(ctx, parsed.(*ProfileParams))
 	case string(MethodStopCPUProfile):
diff --git a/tsc/internal/api/session_format_diagnostics_test.go b/tsc/internal/api/session_format_diagnostics_test.go
new file mode 100644
index 0000000000000..3bea9603f9568
--- /dev/null
+++ b/tsc/internal/api/session_format_diagnostics_test.go
@@ -0,0 +1,346 @@
+package api
+
+import (
+	"context"
+	"strings"
+	"testing"
+
+	"github.com/microsoft/TypeScript/tsc/internal/bundled"
+	"github.com/microsoft/TypeScript/tsc/internal/diagnostics"
+	"github.com/microsoft/TypeScript/tsc/internal/testutil/projecttestutil"
+	"gotest.tools/v3/assert"
+)
+
+func setupFormatSession(t *testing.T, files map[string]any, mainFile string) (*Session, SnapshotID, ProjectID) {
+	t.Helper()
+	projectSession, _ := projecttestutil.Setup(files)
+	t.Cleanup(projectSession.Close)
+	session := NewSession(projectSession, nil)
+	t.Cleanup(session.Close)
+
+	ctx := context.Background()
+	snap, err := session.handleUpdateSnapshot(ctx, &UpdateSnapshotParams{
+		OpenFiles: []DocumentIdentifier{{FileName: mainFile}},
+	})
+	assert.NilError(t, err)
+	proj, err := session.handleGetDefaultProjectForFile(ctx, &GetDefaultProjectForFileParams{
+		Snapshot: snap.Snapshot,
+		File:     DocumentIdentifier{FileName: mainFile},
+	})
+	assert.NilError(t, err)
+	assert.Assert(t, proj != nil, "file should resolve to a default project")
+	return session, snap.Snapshot, proj.Id
+}
+
+func formatDiagnosticsParams(snapshot SnapshotID, project ProjectID, diagnostics []*DiagnosticResponse) *FormatDiagnosticsParams {
+	var setOrigin func([]*DiagnosticResponse)
+	setOrigin = func(diags []*DiagnosticResponse) {
+		for _, diag := range diags {
+			diag.OriginSnapshot = snapshot
+			diag.OriginProject = project
+			setOrigin(diag.MessageChain)
+			setOrigin(diag.RelatedInformation)
+		}
+	}
+	setOrigin(diagnostics)
+	return &FormatDiagnosticsParams{
+		Snapshot:    snapshot,
+		Project:     project,
+		Diagnostics: diagnostics,
+		NewLine:     "\n",
+	}
+}
+
+func TestFormatDiagnostics(t *testing.T) {
+	t.Parallel()
+	if !bundled.Embedded {
+		t.Skip("bundled files are not embedded")
+	}
+
+	const fileName = "/home/projects/p/src/index.ts"
+	const content = "const x: number = \"oops\";\n"
+	session, snapshot, project := setupFormatSession(t, map[string]any{
+		"/home/projects/p/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+		fileName:                         content,
+	}, fileName)
+	ctx := context.Background()
+
+	diags, err := session.handleGetSemanticDiagnostics(ctx, &GetDiagnosticsParams{
+		Snapshot: snapshot,
+		Project:  project,
+		Files:    []DocumentIdentifier{{FileName: fileName}},
+	})
+	assert.NilError(t, err)
+	assert.Equal(t, len(diags), 1)
+
+	plain, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, diags), false /*colorAndContext*/)
+	assert.NilError(t, err)
+	assert.Equal(t, plain.Output,
+		"home/projects/p/src/index.ts(1,7): error TS2322: Type 'string' is not assignable to type 'number'.\n")
+
+	color, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, diags), true /*colorAndContext*/)
+	assert.NilError(t, err)
+	assert.Assert(t, strings.Contains(color.Output, "home/projects/p/src/index.ts"))
+	assert.Assert(t, strings.Contains(color.Output, "error"))
+	assert.Assert(t, strings.Contains(color.Output, "TS2322: "))
+	assert.Assert(t, strings.Contains(color.Output, "Type 'string' is not assignable to type 'number'."))
+	assert.Assert(t, strings.Contains(color.Output, "const x: number = \"oops\";"))
+	assert.Assert(t, strings.Contains(color.Output, "~"))
+	assert.Assert(t, strings.Contains(color.Output, "\x1b["))
+}
+
+func TestFormatDiagnosticsPreservesHostFormattedAbsolutePath(t *testing.T) {
+	t.Parallel()
+	if !bundled.Embedded {
+		t.Skip("bundled files are not embedded")
+	}
+
+	const fileName = "/home/projects/p/src/index.ts"
+	session, snapshot, project := setupFormatSession(t, map[string]any{
+		"/home/projects/p/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+		fileName:                         `const x: number = "oops";`,
+	}, fileName)
+	ctx := context.Background()
+
+	diags, err := session.handleGetSemanticDiagnostics(ctx, &GetDiagnosticsParams{
+		Snapshot: snapshot,
+		Project:  project,
+		Files:    []DocumentIdentifier{{FileName: fileName}},
+	})
+	assert.NilError(t, err)
+	assert.Equal(t, len(diags), 1)
+	diags[0].DisplayFileName = "/different/root/index.ts"
+
+	params := formatDiagnosticsParams(snapshot, project, diags)
+	plain, err := session.handleFormatDiagnostics(ctx, params, false)
+	assert.NilError(t, err)
+	assert.Assert(t, strings.HasPrefix(plain.Output, "/different/root/index.ts(1,7): "))
+
+	color, err := session.handleFormatDiagnostics(ctx, params, true)
+	assert.NilError(t, err)
+	assert.Assert(t, strings.Contains(color.Output, "\x1b[96m/different/root/index.ts\x1b[0m:"))
+}
+
+func TestFormatDiagnosticsConfigFileContext(t *testing.T) {
+	t.Parallel()
+	if !bundled.Embedded {
+		t.Skip("bundled files are not embedded")
+	}
+
+	const configFileName = "/home/projects/p/tsconfig.json"
+	const config = "{ \"compilerOptions\": { \"target\": \"invalid\" } }"
+	const mainFile = "/home/projects/p/src/index.ts"
+	session, snapshot, project := setupFormatSession(t, map[string]any{
+		configFileName: config,
+		mainFile:       "export const x = 1;\n",
+	}, mainFile)
+	ctx := context.Background()
+
+	diags, err := session.handleGetConfigFileParsingDiagnostics(ctx, &GetProjectDiagnosticsParams{
+		Snapshot: snapshot, Project: project,
+	})
+	assert.NilError(t, err)
+	assert.Equal(t, len(diags), 1)
+	assert.Equal(t, diags[0].FileName, configFileName)
+
+	plain, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, diags), false)
+	assert.NilError(t, err)
+	assert.Assert(t, strings.HasPrefix(plain.Output, "home/projects/p/tsconfig.json(1,34): error TS6046: "))
+
+	color, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, diags), true)
+	assert.NilError(t, err)
+	assert.Assert(t, strings.Contains(color.Output, "\"target\": \"invalid\""))
+	assert.Assert(t, strings.Contains(color.Output, "~~~~~~~~~"))
+}
+
+func TestFormatDiagnosticsWithoutFile(t *testing.T) {
+	t.Parallel()
+	if !bundled.Embedded {
+		t.Skip("bundled files are not embedded")
+	}
+
+	const fileName = "/home/projects/p/src/index.ts"
+	session, snapshot, project := setupFormatSession(t, map[string]any{
+		"/home/projects/p/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+		fileName:                         "export const x = 1;\n",
+	}, fileName)
+	ctx := context.Background()
+
+	fileless := []*DiagnosticResponse{{
+		Code:     1234,
+		Category: diagnostics.CategoryError,
+		Text:     "Some global problem.",
+		RelatedInformation: []*DiagnosticResponse{{
+			Code:     5678,
+			Category: diagnostics.CategoryMessage,
+			Text:     "Additional context.",
+		}},
+	}}
+
+	plain, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, fileless), false)
+	assert.NilError(t, err)
+	assert.Equal(t, plain.Output, "error TS1234: Some global problem.\n")
+
+	color, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, fileless), true)
+	assert.NilError(t, err)
+	assert.Equal(t, color.Output,
+		"\x1b[91merror\x1b[0m\x1b[90m TS1234: \x1b[0mSome global problem.\n\n    Additional context.\n")
+}
+
+func TestFormatDiagnosticsClampsOutOfRangePositions(t *testing.T) {
+	t.Parallel()
+	if !bundled.Embedded {
+		t.Skip("bundled files are not embedded")
+	}
+
+	const fileName = "/home/projects/p/src/index.ts"
+	session, snapshot, project := setupFormatSession(t, map[string]any{
+		"/home/projects/p/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+		fileName:                         "export const x = 1;\n",
+	}, fileName)
+	ctx := context.Background()
+
+	stale := []*DiagnosticResponse{{
+		FileName: fileName,
+		Pos:      100_000,
+		End:      200_000,
+		Code:     1234,
+		Category: diagnostics.CategoryError,
+		Text:     "Stale diagnostic.",
+	}}
+
+	plain, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, stale), false)
+	assert.NilError(t, err)
+	assert.Equal(t, plain.Output,
+		"home/projects/p/src/index.ts(2,1): error TS1234: Stale diagnostic.\n")
+
+	color, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, stale), true)
+	assert.NilError(t, err)
+	assert.Assert(t, strings.Contains(color.Output, "TS1234: "))
+	assert.Assert(t, strings.Contains(color.Output, "Stale diagnostic."))
+}
+
+func TestFormatDiagnosticsRejectsMismatchedOrMissingSources(t *testing.T) {
+	t.Parallel()
+	if !bundled.Embedded {
+		t.Skip("bundled files are not embedded")
+	}
+
+	const fileName = "/home/projects/p/src/index.ts"
+	session, snapshot, project := setupFormatSession(t, map[string]any{
+		"/home/projects/p/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+		fileName:                         "export const x = 1;\n",
+	}, fileName)
+	ctx := context.Background()
+
+	mismatched := formatDiagnosticsParams(snapshot, project, []*DiagnosticResponse{{
+		Code:     1234,
+		Category: diagnostics.CategoryError,
+		Text:     "Wrong program.",
+	}})
+	mismatched.Diagnostics[0].OriginSnapshot++
+	_, err := session.handleFormatDiagnostics(ctx, mismatched, false)
+	assert.ErrorContains(t, err, "diagnostic was not produced by this program")
+
+	missing := formatDiagnosticsParams(snapshot, project, []*DiagnosticResponse{{
+		FileName: "/home/projects/p/src/missing.ts",
+		Code:     1234,
+		Category: diagnostics.CategoryError,
+		Text:     "Missing source.",
+	}})
+	_, err = session.handleFormatDiagnostics(ctx, missing, false)
+	assert.ErrorContains(t, err, "diagnostic source file not found")
+}
+
+func TestFormatDiagnosticsNonASCIIPositions(t *testing.T) {
+	t.Parallel()
+	if !bundled.Embedded {
+		t.Skip("bundled files are not embedded")
+	}
+
+	const fileName = "/home/projects/p/src/index.ts"
+	// "é" is 2 UTF-8 bytes and 1 UTF-16 code unit.
+	const content = "const café = 1;\nconst x: number = \"oops\";\n"
+	session, snapshot, project := setupFormatSession(t, map[string]any{
+		"/home/projects/p/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+		fileName:                         content,
+	}, fileName)
+	ctx := context.Background()
+
+	diags, err := session.handleGetSemanticDiagnostics(ctx, &GetDiagnosticsParams{
+		Snapshot: snapshot, Project: project, Files: []DocumentIdentifier{{FileName: fileName}},
+	})
+	assert.NilError(t, err)
+	assert.Equal(t, len(diags), 1)
+
+	plain, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, diags), false)
+	assert.NilError(t, err)
+	assert.Equal(t, plain.Output,
+		"home/projects/p/src/index.ts(2,7): error TS2322: Type 'string' is not assignable to type 'number'.\n")
+
+	color, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, diags), true)
+	assert.NilError(t, err)
+	assert.Assert(t, strings.Contains(color.Output, "const x: number = \"oops\";"))
+	assert.Assert(t, strings.Contains(color.Output, "~"))
+}
+
+func TestFormatDiagnosticsAstralPositions(t *testing.T) {
+	t.Parallel()
+	if !bundled.Embedded {
+		t.Skip("bundled files are not embedded")
+	}
+
+	const fileName = "/home/projects/p/src/index.ts"
+	// "😀" is 4 UTF-8 bytes and 2 UTF-16 code units.
+	const content = "const emoji = \"😀\";\nconst x: number = \"oops\";\n"
+	session, snapshot, project := setupFormatSession(t, map[string]any{
+		"/home/projects/p/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+		fileName:                         content,
+	}, fileName)
+	ctx := context.Background()
+
+	diags, err := session.handleGetSemanticDiagnostics(ctx, &GetDiagnosticsParams{
+		Snapshot: snapshot, Project: project, Files: []DocumentIdentifier{{FileName: fileName}},
+	})
+	assert.NilError(t, err)
+	assert.Equal(t, len(diags), 1)
+
+	plain, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, diags), false)
+	assert.NilError(t, err)
+	assert.Equal(t, plain.Output,
+		"home/projects/p/src/index.ts(2,7): error TS2322: Type 'string' is not assignable to type 'number'.\n")
+
+	color, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, diags), true)
+	assert.NilError(t, err)
+	assert.Assert(t, strings.Contains(color.Output, "const x: number = \"oops\";"))
+	assert.Assert(t, strings.Contains(color.Output, "~"))
+}
+
+func TestFormatDiagnosticsMessageChainAndRelatedInformation(t *testing.T) {
+	t.Parallel()
+	if !bundled.Embedded {
+		t.Skip("bundled files are not embedded")
+	}
+
+	const fileName = "/home/projects/p/src/index.ts"
+	const content = "interface Props { callback: (x: string) => void }\nconst p: Props = { callback: (x: number) => {} };\n"
+	session, snapshot, project := setupFormatSession(t, map[string]any{
+		"/home/projects/p/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+		fileName:                         content,
+	}, fileName)
+	ctx := context.Background()
+
+	diags, err := session.handleGetSemanticDiagnostics(ctx, &GetDiagnosticsParams{
+		Snapshot: snapshot, Project: project, Files: []DocumentIdentifier{{FileName: fileName}},
+	})
+	assert.NilError(t, err)
+	assert.Equal(t, len(diags), 1)
+	assert.Assert(t, len(diags[0].MessageChain) > 0, "expected a message chain")
+	assert.Assert(t, len(diags[0].RelatedInformation) > 0, "expected related information")
+
+	color, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, diags), true)
+	assert.NilError(t, err)
+	assert.Assert(t, strings.Contains(color.Output, "is not assignable to type"))
+	assert.Assert(t, strings.Contains(color.Output, "Types of parameters 'x' and 'x' are incompatible."))
+	assert.Assert(t, strings.Contains(color.Output, "The expected type comes from property 'callback'"))
+}
diff --git a/tsc/internal/diagnosticwriter/diagnosticwriter.go b/tsc/internal/diagnosticwriter/diagnosticwriter.go
index 57aee4053410c..01626fb62a962 100644
--- a/tsc/internal/diagnosticwriter/diagnosticwriter.go
+++ b/tsc/internal/diagnosticwriter/diagnosticwriter.go
@@ -199,13 +199,7 @@ const (
 )
 
 func FormatDiagnosticsWithColorAndContext(output io.Writer, diags []Diagnostic, formatOpts *FormattingOptions) {
-	if len(diags) == 0 {
-		return
-	}
-	for i, diagnostic := range diags {
-		if i > 0 {
-			fmt.Fprint(output, formatOpts.NewLine)
-		}
+	for _, diagnostic := range diags {
 		FormatDiagnosticWithColorAndContext(output, diagnostic, formatOpts)
 	}
 }
@@ -225,10 +219,10 @@ func FormatDiagnosticWithColorAndContext(output io.Writer, diagnostic Diagnostic
 	if diagnostic.File() != nil && diagnostic.Code() != diagnostics.File_appears_to_be_binary.Code() {
 		fmt.Fprint(output, formatOpts.NewLine)
 		writeCodeSnippet(output, diagnostic.File(), diagnostic.Pos(), diagnostic.Len(), getCategoryFormat(diagnostic.Category()), "", formatOpts)
-		fmt.Fprint(output, formatOpts.NewLine)
 	}
 
-	if (diagnostic.RelatedInformation() != nil) && (len(diagnostic.RelatedInformation()) > 0) {
+	if len(diagnostic.RelatedInformation()) > 0 {
+		fmt.Fprint(output, formatOpts.NewLine)
 		for _, relatedInformation := range diagnostic.RelatedInformation() {
 			file := relatedInformation.File()
 			if file != nil {
@@ -236,13 +230,14 @@ func FormatDiagnosticWithColorAndContext(output io.Writer, diagnostic Diagnostic
 				fmt.Fprint(output, "  ")
 				pos := relatedInformation.Pos()
 				WriteLocation(output, file, pos, formatOpts, writeWithStyleAndReset)
-				fmt.Fprint(output, " - ")
-				WriteFlattenedDiagnosticMessage(output, relatedInformation, formatOpts.NewLine, formatOpts.Locale)
 				writeCodeSnippet(output, file, pos, relatedInformation.Len(), foregroundColorEscapeCyan, "    ", formatOpts)
 			}
 			fmt.Fprint(output, formatOpts.NewLine)
+			fmt.Fprint(output, "    ")
+			WriteFlattenedDiagnosticMessage(output, relatedInformation, formatOpts.NewLine, formatOpts.Locale)
 		}
 	}
+	fmt.Fprint(output, formatOpts.NewLine)
 }
 
 func writeCodeSnippet(writer io.Writer, sourceFile FileLike, start int, length int, squiggleColor string, indent string, formatOpts *FormattingOptions) {
@@ -393,7 +388,7 @@ func writeWithStyleAndReset(output io.Writer, text string, formatStyle string) {
 func WriteLocation(output io.Writer, file FileLike, pos int, formatOpts *FormattingOptions, writeWithStyleAndReset FormattedWriter) {
 	firstLine, firstChar := scanner.GetECMALineAndUTF16CharacterOfPosition(file, pos)
 	var relativeFileName string
-	if formatOpts != nil {
+	if formatOpts != nil && !fileNameIsFormatted(file) {
 		relativeFileName = tspath.ConvertToRelativePath(file.FileName(), formatOpts.ComparePathsOptions)
 	} else {
 		relativeFileName = file.FileName()
@@ -556,7 +551,10 @@ func WriteFormatDiagnostic(output io.Writer, diagnostic Diagnostic, formatOpts *
 	if diagnostic.File() != nil {
 		line, character := scanner.GetECMALineAndUTF16CharacterOfPosition(diagnostic.File(), diagnostic.Pos())
 		fileName := diagnostic.File().FileName()
-		relativeFileName := tspath.ConvertToRelativePath(fileName, formatOpts.ComparePathsOptions)
+		relativeFileName := fileName
+		if !fileNameIsFormatted(diagnostic.File()) {
+			relativeFileName = tspath.ConvertToRelativePath(fileName, formatOpts.ComparePathsOptions)
+		}
 		fmt.Fprintf(output, "%s(%d,%d): ", relativeFileName, line+1, int(character)+1)
 	}
 
@@ -565,6 +563,11 @@ func WriteFormatDiagnostic(output io.Writer, diagnostic Diagnostic, formatOpts *
 	fmt.Fprint(output, formatOpts.NewLine)
 }
 
+func fileNameIsFormatted(file FileLike) bool {
+	formatted, ok := file.(interface{ FileNameIsFormatted() bool })
+	return ok && formatted.FileNameIsFormatted()
+}
+
 func FormatDiagnosticsStatusWithColorAndTime(output io.Writer, time string, diag Diagnostic, formatOpts *FormattingOptions) {
 	fmt.Fprint(output, "[")
 	writeWithStyleAndReset(output, time, foregroundColorEscapeGrey)
diff --git a/tsc/internal/tsoptions/tsconfigparsing_test.go b/tsc/internal/tsoptions/tsconfigparsing_test.go
index 9b4d054bbacec..ead33c504486e 100644
--- a/tsc/internal/tsoptions/tsconfigparsing_test.go
+++ b/tsc/internal/tsoptions/tsconfigparsing_test.go
@@ -146,7 +146,9 @@ func TestParseConfigFileTextToJson(t *testing.T) {
 						UseCaseSensitiveFileNames: true,
 					},
 				})
-				baselineContent.WriteString("\n")
+				if len(errors) == 0 {
+					baselineContent.WriteString("\n")
+				}
 				if i != len(rec.input)-1 {
 					baselineContent.WriteString("\n")
 				}
@@ -1478,7 +1480,9 @@ func baselineParseConfigWith(t *testing.T, baselineFileName string, includeCompi
 				UseCaseSensitiveFileNames: true,
 			},
 		})
-		baselineContent.WriteString("\n")
+		if len(parsedConfigFileContent.Errors) == 0 {
+			baselineContent.WriteString("\n")
+		}
 		if i != len(input)-1 {
 			baselineContent.WriteString("\n")
 		}
diff --git a/tsc/testdata/baselines/reference/compiler/contentMapperDiagnosticDirectives.contentmapper b/tsc/testdata/baselines/reference/compiler/contentMapperDiagnosticDirectives.contentmapper
index aeafe71315828..b5a663f3e2199 100644
--- a/tsc/testdata/baselines/reference/compiler/contentMapperDiagnosticDirectives.contentmapper
+++ b/tsc/testdata/baselines/reference/compiler/contentMapperDiagnosticDirectives.contentmapper
@@ -41,27 +41,22 @@ export const broken = undefined
 
 7 // @box-expect-error: Syntax errors do not satisfy expectations.
   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
 /widget.box:10:1 - error box2578: Unused second expectation.
 
 10 // @box-expect-error: Unused second expectation.
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
 /widget.box:8:21 - error TS1109: Expression expected.
 
 8 const syntaxError = ;
                       ~
-
 /widget.box:13:7 - error TS2322: Type 'string' is not assignable to type 'number'.
 
 13 const visible: number = "wrong";
          ~~~~~~~
-
 /widget.box:15:1 - error box2578: Mapper diagnostics do not satisfy expectations.
 
 15 // @box-expect-error: Mapper diagnostics do not satisfy expectations.
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
 /widget.box:16:23 - error box1000: Unclosed interpolation.
 
 16 export const broken = #{unterminated;
diff --git a/tsc/testdata/baselines/reference/compiler/contentMapperDiagnostics.contentmapper b/tsc/testdata/baselines/reference/compiler/contentMapperDiagnostics.contentmapper
index 223287609cb54..088e43b12d109 100644
--- a/tsc/testdata/baselines/reference/compiler/contentMapperDiagnostics.contentmapper
+++ b/tsc/testdata/baselines/reference/compiler/contentMapperDiagnostics.contentmapper
@@ -15,12 +15,10 @@ export const broken = undefined
 
 1 export const count: number = "not a number";
                ~~~~~
-
 /widget.box:2:14 - error TS2322: Type 'number' is not assignable to type 'string'.
 
 2 export const label: string = #{target};
                ~~~~~
-
 /widget.box:3:23 - error box1000: Unclosed interpolation.
 
 3 export const broken = #{unterminated;
diff --git a/tsc/testdata/baselines/reference/compiler/contentMapperInvalidDiagnosticDirectives.contentmapper b/tsc/testdata/baselines/reference/compiler/contentMapperInvalidDiagnosticDirectives.contentmapper
index 8ea467db00dd4..9c5858339f865 100644
--- a/tsc/testdata/baselines/reference/compiler/contentMapperInvalidDiagnosticDirectives.contentmapper
+++ b/tsc/testdata/baselines/reference/compiler/contentMapperInvalidDiagnosticDirectives.contentmapper
@@ -30,25 +30,21 @@
 
 1 
   ~
-
 /invalidPolicy.invalidpolicy:1:1 - error TS100025: The content mapper 'mapper' failed to transform this file.
   The content mapper returned a diagnostic directive with invalid policy '2'.
 
 1 
   ~
-
 /invalidRange.invalidrange:1:1 - error TS100025: The content mapper 'mapper' failed to transform this file.
   Diagnostic directive 0 returned by the content mapper has an invalid range.
 
 1 
   ~
-
 /invalidUnusedDiagnosticIndex.invalidunusedindex:1:1 - error TS100025: The content mapper 'mapper' failed to transform this file.
   Diagnostic directive 0 returned by the content mapper has an invalid 'unusedExpectDirectiveIndex'.
 
 1 
   ~
-
 /overlap.overlap:1:1 - error TS100025: The content mapper 'mapper' failed to transform this file.
   The content mapper returned diagnostic directives with overlapping virtual ranges.
 
diff --git a/tsc/testdata/baselines/reference/compiler/deeplyNestedAssignabilityIssue.errors.txt b/tsc/testdata/baselines/reference/compiler/deeplyNestedAssignabilityIssue.errors.txt
index 27a65bedc6dbd..5add2fd996c3a 100644
--- a/tsc/testdata/baselines/reference/compiler/deeplyNestedAssignabilityIssue.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/deeplyNestedAssignabilityIssue.errors.txt
@@ -3,26 +3,27 @@
 22                 thing: {}
                    ~~~~~
 
-  deeplyNestedAssignabilityIssue.ts:2:5 - 'a' is declared here.
+  deeplyNestedAssignabilityIssue.ts:2:5
     2     a: number;
           ~
-
-  deeplyNestedAssignabilityIssue.ts:9:17 - The expected type comes from property 'thing' which is declared here on type '{ thing: A; }'
+    'a' is declared here.
+  deeplyNestedAssignabilityIssue.ts:9:17
     9                 thing: A;
                       ~~~~~
-
+    The expected type comes from property 'thing' which is declared here on type '{ thing: A; }'
 deeplyNestedAssignabilityIssue.ts:25:17 - error TS2741: Property 'a' is missing in type '{}' but required in type 'A'.
 
 25                 another: {}
                    ~~~~~~~
 
-  deeplyNestedAssignabilityIssue.ts:2:5 - 'a' is declared here.
+  deeplyNestedAssignabilityIssue.ts:2:5
     2     a: number;
           ~
-
-  deeplyNestedAssignabilityIssue.ts:12:17 - The expected type comes from property 'another' which is declared here on type '{ another: A; }'
+    'a' is declared here.
+  deeplyNestedAssignabilityIssue.ts:12:17
     12                 another: A;
                        ~~~~~~~
+    The expected type comes from property 'another' which is declared here on type '{ another: A; }'
 
 
 ==== deeplyNestedAssignabilityIssue.ts (2 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans1.errors.txt b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans1.errors.txt
index bf30f2c3fc40c..9af458a195d63 100644
--- a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans1.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans1.errors.txt
@@ -3,62 +3,63 @@
 1 class Foo { }
         ~~~
 
-  file2.ts:1:6 - 'Foo' was also declared here.
+  file2.ts:1:6
     1 type Foo = number;
            ~~~
-
-  file3.ts:1:6 - 'Foo' was also declared here.
+    'Foo' was also declared here.
+  file3.ts:1:6
     1 type Foo = 54;
            ~~~
-
+    'Foo' was also declared here.
 file1.ts:2:7 - error TS2451: Cannot redeclare block-scoped variable 'Bar'.
 
 2 const Bar = 3;
         ~~~
 
-  file2.ts:2:7 - 'Bar' was also declared here.
+  file2.ts:2:7
     2 class Bar {}
             ~~~
-
-  file3.ts:2:5 - 'Bar' was also declared here.
+    'Bar' was also declared here.
+  file3.ts:2:5
     2 let Bar = 42
           ~~~
-
+    'Bar' was also declared here.
 file2.ts:1:6 - error TS2300: Duplicate identifier 'Foo'.
 
 1 type Foo = number;
        ~~~
 
-  file1.ts:1:7 - 'Foo' was also declared here.
+  file1.ts:1:7
     1 class Foo { }
             ~~~
-
+    'Foo' was also declared here.
 file2.ts:2:7 - error TS2451: Cannot redeclare block-scoped variable 'Bar'.
 
 2 class Bar {}
         ~~~
 
-  file1.ts:2:7 - 'Bar' was also declared here.
+  file1.ts:2:7
     2 const Bar = 3;
             ~~~
-
+    'Bar' was also declared here.
 file3.ts:1:6 - error TS2300: Duplicate identifier 'Foo'.
 
 1 type Foo = 54;
        ~~~
 
-  file1.ts:1:7 - 'Foo' was also declared here.
+  file1.ts:1:7
     1 class Foo { }
             ~~~
-
+    'Foo' was also declared here.
 file3.ts:2:5 - error TS2451: Cannot redeclare block-scoped variable 'Bar'.
 
 2 let Bar = 42
       ~~~
 
-  file1.ts:2:7 - 'Bar' was also declared here.
+  file1.ts:2:7
     2 const Bar = 3;
             ~~~
+    'Bar' was also declared here.
 
 
 ==== file1.ts (2 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans2.errors.txt b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans2.errors.txt
index f26290ce4096f..69e8f479c68ec 100644
--- a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans2.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans2.errors.txt
@@ -3,162 +3,163 @@
 1 class A { }
         ~
 
-  file2.ts:1:7 - 'A' was also declared here.
+  file2.ts:1:7
     1 class A { }
             ~
-
+    'A' was also declared here.
 file1.ts:2:7 - error TS2300: Duplicate identifier 'B'.
 
 2 class B { }
         ~
 
-  file2.ts:2:7 - 'B' was also declared here.
+  file2.ts:2:7
     2 class B { }
             ~
-
+    'B' was also declared here.
 file1.ts:3:7 - error TS2300: Duplicate identifier 'C'.
 
 3 class C { }
         ~
 
-  file2.ts:3:7 - 'C' was also declared here.
+  file2.ts:3:7
     3 class C { }
             ~
-
+    'C' was also declared here.
 file1.ts:4:7 - error TS2300: Duplicate identifier 'D'.
 
 4 class D { }
         ~
 
-  file2.ts:4:7 - 'D' was also declared here.
+  file2.ts:4:7
     4 class D { }
             ~
-
+    'D' was also declared here.
 file1.ts:5:7 - error TS2300: Duplicate identifier 'E'.
 
 5 class E { }
         ~
 
-  file2.ts:5:7 - 'E' was also declared here.
+  file2.ts:5:7
     5 class E { }
             ~
-
+    'E' was also declared here.
 file1.ts:6:7 - error TS2300: Duplicate identifier 'F'.
 
 6 class F { }
         ~
 
-  file2.ts:6:7 - 'F' was also declared here.
+  file2.ts:6:7
     6 class F { }
             ~
-
+    'F' was also declared here.
 file1.ts:7:7 - error TS2300: Duplicate identifier 'G'.
 
 7 class G { }
         ~
 
-  file2.ts:7:7 - 'G' was also declared here.
+  file2.ts:7:7
     7 class G { }
             ~
-
+    'G' was also declared here.
 file1.ts:8:7 - error TS2300: Duplicate identifier 'H'.
 
 8 class H { }
         ~
 
-  file2.ts:8:7 - 'H' was also declared here.
+  file2.ts:8:7
     8 class H { }
             ~
-
+    'H' was also declared here.
 file1.ts:9:7 - error TS2300: Duplicate identifier 'I'.
 
 9 class I { }
         ~
 
-  file2.ts:9:7 - 'I' was also declared here.
+  file2.ts:9:7
     9 class I { }
             ~
-
+    'I' was also declared here.
 file2.ts:1:7 - error TS2300: Duplicate identifier 'A'.
 
 1 class A { }
         ~
 
-  file1.ts:1:7 - 'A' was also declared here.
+  file1.ts:1:7
     1 class A { }
             ~
-
+    'A' was also declared here.
 file2.ts:2:7 - error TS2300: Duplicate identifier 'B'.
 
 2 class B { }
         ~
 
-  file1.ts:2:7 - 'B' was also declared here.
+  file1.ts:2:7
     2 class B { }
             ~
-
+    'B' was also declared here.
 file2.ts:3:7 - error TS2300: Duplicate identifier 'C'.
 
 3 class C { }
         ~
 
-  file1.ts:3:7 - 'C' was also declared here.
+  file1.ts:3:7
     3 class C { }
             ~
-
+    'C' was also declared here.
 file2.ts:4:7 - error TS2300: Duplicate identifier 'D'.
 
 4 class D { }
         ~
 
-  file1.ts:4:7 - 'D' was also declared here.
+  file1.ts:4:7
     4 class D { }
             ~
-
+    'D' was also declared here.
 file2.ts:5:7 - error TS2300: Duplicate identifier 'E'.
 
 5 class E { }
         ~
 
-  file1.ts:5:7 - 'E' was also declared here.
+  file1.ts:5:7
     5 class E { }
             ~
-
+    'E' was also declared here.
 file2.ts:6:7 - error TS2300: Duplicate identifier 'F'.
 
 6 class F { }
         ~
 
-  file1.ts:6:7 - 'F' was also declared here.
+  file1.ts:6:7
     6 class F { }
             ~
-
+    'F' was also declared here.
 file2.ts:7:7 - error TS2300: Duplicate identifier 'G'.
 
 7 class G { }
         ~
 
-  file1.ts:7:7 - 'G' was also declared here.
+  file1.ts:7:7
     7 class G { }
             ~
-
+    'G' was also declared here.
 file2.ts:8:7 - error TS2300: Duplicate identifier 'H'.
 
 8 class H { }
         ~
 
-  file1.ts:8:7 - 'H' was also declared here.
+  file1.ts:8:7
     8 class H { }
             ~
-
+    'H' was also declared here.
 file2.ts:9:7 - error TS2300: Duplicate identifier 'I'.
 
 9 class I { }
         ~
 
-  file1.ts:9:7 - 'I' was also declared here.
+  file1.ts:9:7
     9 class I { }
             ~
+    'I' was also declared here.
 
 
 ==== file1.ts (9 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans3.errors.txt b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans3.errors.txt
index e61e71853317b..b08664db5ce5a 100644
--- a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans3.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans3.errors.txt
@@ -3,54 +3,55 @@
 2     duplicate1: () => string;
       ~~~~~~~~~~
 
-  file2.ts:2:5 - 'duplicate1' was also declared here.
+  file2.ts:2:5
     2     duplicate1(): number;
           ~~~~~~~~~~
-
+    'duplicate1' was also declared here.
 file1.ts:3:5 - error TS2300: Duplicate identifier 'duplicate2'.
 
 3     duplicate2: () => string;
       ~~~~~~~~~~
 
-  file2.ts:3:5 - 'duplicate2' was also declared here.
+  file2.ts:3:5
     3     duplicate2(): number;
           ~~~~~~~~~~
-
+    'duplicate2' was also declared here.
 file1.ts:4:5 - error TS2300: Duplicate identifier 'duplicate3'.
 
 4     duplicate3: () => string;
       ~~~~~~~~~~
 
-  file2.ts:4:5 - 'duplicate3' was also declared here.
+  file2.ts:4:5
     4     duplicate3(): number;
           ~~~~~~~~~~
-
+    'duplicate3' was also declared here.
 file2.ts:2:5 - error TS2300: Duplicate identifier 'duplicate1'.
 
 2     duplicate1(): number;
       ~~~~~~~~~~
 
-  file1.ts:2:5 - 'duplicate1' was also declared here.
+  file1.ts:2:5
     2     duplicate1: () => string;
           ~~~~~~~~~~
-
+    'duplicate1' was also declared here.
 file2.ts:3:5 - error TS2300: Duplicate identifier 'duplicate2'.
 
 3     duplicate2(): number;
       ~~~~~~~~~~
 
-  file1.ts:3:5 - 'duplicate2' was also declared here.
+  file1.ts:3:5
     3     duplicate2: () => string;
           ~~~~~~~~~~
-
+    'duplicate2' was also declared here.
 file2.ts:4:5 - error TS2300: Duplicate identifier 'duplicate3'.
 
 4     duplicate3(): number;
       ~~~~~~~~~~
 
-  file1.ts:4:5 - 'duplicate3' was also declared here.
+  file1.ts:4:5
     4     duplicate3: () => string;
           ~~~~~~~~~~
+    'duplicate3' was also declared here.
 
 
 ==== file1.ts (3 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans4.errors.txt b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans4.errors.txt
index 3cf299fdb9d2e..c6088fa352d7c 100644
--- a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans4.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans4.errors.txt
@@ -3,144 +3,145 @@
 2     duplicate1: () => string;
       ~~~~~~~~~~
 
-  file2.ts:2:5 - 'duplicate1' was also declared here.
+  file2.ts:2:5
     2     duplicate1(): number;
           ~~~~~~~~~~
-
+    'duplicate1' was also declared here.
 file1.ts:3:5 - error TS2300: Duplicate identifier 'duplicate2'.
 
 3     duplicate2: () => string;
       ~~~~~~~~~~
 
-  file2.ts:3:5 - 'duplicate2' was also declared here.
+  file2.ts:3:5
     3     duplicate2(): number;
           ~~~~~~~~~~
-
+    'duplicate2' was also declared here.
 file1.ts:4:5 - error TS2300: Duplicate identifier 'duplicate3'.
 
 4     duplicate3: () => string;
       ~~~~~~~~~~
 
-  file2.ts:4:5 - 'duplicate3' was also declared here.
+  file2.ts:4:5
     4     duplicate3(): number;
           ~~~~~~~~~~
-
+    'duplicate3' was also declared here.
 file1.ts:5:5 - error TS2300: Duplicate identifier 'duplicate4'.
 
 5     duplicate4: () => string;
       ~~~~~~~~~~
 
-  file2.ts:5:5 - 'duplicate4' was also declared here.
+  file2.ts:5:5
     5     duplicate4(): number;
           ~~~~~~~~~~
-
+    'duplicate4' was also declared here.
 file1.ts:6:5 - error TS2300: Duplicate identifier 'duplicate5'.
 
 6     duplicate5: () => string;
       ~~~~~~~~~~
 
-  file2.ts:6:5 - 'duplicate5' was also declared here.
+  file2.ts:6:5
     6     duplicate5(): number;
           ~~~~~~~~~~
-
+    'duplicate5' was also declared here.
 file1.ts:7:5 - error TS2300: Duplicate identifier 'duplicate6'.
 
 7     duplicate6: () => string;
       ~~~~~~~~~~
 
-  file2.ts:7:5 - 'duplicate6' was also declared here.
+  file2.ts:7:5
     7     duplicate6(): number;
           ~~~~~~~~~~
-
+    'duplicate6' was also declared here.
 file1.ts:8:5 - error TS2300: Duplicate identifier 'duplicate7'.
 
 8     duplicate7: () => string;
       ~~~~~~~~~~
 
-  file2.ts:8:5 - 'duplicate7' was also declared here.
+  file2.ts:8:5
     8     duplicate7(): number;
           ~~~~~~~~~~
-
+    'duplicate7' was also declared here.
 file1.ts:9:5 - error TS2300: Duplicate identifier 'duplicate8'.
 
 9     duplicate8: () => string;
       ~~~~~~~~~~
 
-  file2.ts:9:5 - 'duplicate8' was also declared here.
+  file2.ts:9:5
     9     duplicate8(): number;
           ~~~~~~~~~~
-
+    'duplicate8' was also declared here.
 file2.ts:2:5 - error TS2300: Duplicate identifier 'duplicate1'.
 
 2     duplicate1(): number;
       ~~~~~~~~~~
 
-  file1.ts:2:5 - 'duplicate1' was also declared here.
+  file1.ts:2:5
     2     duplicate1: () => string;
           ~~~~~~~~~~
-
+    'duplicate1' was also declared here.
 file2.ts:3:5 - error TS2300: Duplicate identifier 'duplicate2'.
 
 3     duplicate2(): number;
       ~~~~~~~~~~
 
-  file1.ts:3:5 - 'duplicate2' was also declared here.
+  file1.ts:3:5
     3     duplicate2: () => string;
           ~~~~~~~~~~
-
+    'duplicate2' was also declared here.
 file2.ts:4:5 - error TS2300: Duplicate identifier 'duplicate3'.
 
 4     duplicate3(): number;
       ~~~~~~~~~~
 
-  file1.ts:4:5 - 'duplicate3' was also declared here.
+  file1.ts:4:5
     4     duplicate3: () => string;
           ~~~~~~~~~~
-
+    'duplicate3' was also declared here.
 file2.ts:5:5 - error TS2300: Duplicate identifier 'duplicate4'.
 
 5     duplicate4(): number;
       ~~~~~~~~~~
 
-  file1.ts:5:5 - 'duplicate4' was also declared here.
+  file1.ts:5:5
     5     duplicate4: () => string;
           ~~~~~~~~~~
-
+    'duplicate4' was also declared here.
 file2.ts:6:5 - error TS2300: Duplicate identifier 'duplicate5'.
 
 6     duplicate5(): number;
       ~~~~~~~~~~
 
-  file1.ts:6:5 - 'duplicate5' was also declared here.
+  file1.ts:6:5
     6     duplicate5: () => string;
           ~~~~~~~~~~
-
+    'duplicate5' was also declared here.
 file2.ts:7:5 - error TS2300: Duplicate identifier 'duplicate6'.
 
 7     duplicate6(): number;
       ~~~~~~~~~~
 
-  file1.ts:7:5 - 'duplicate6' was also declared here.
+  file1.ts:7:5
     7     duplicate6: () => string;
           ~~~~~~~~~~
-
+    'duplicate6' was also declared here.
 file2.ts:8:5 - error TS2300: Duplicate identifier 'duplicate7'.
 
 8     duplicate7(): number;
       ~~~~~~~~~~
 
-  file1.ts:8:5 - 'duplicate7' was also declared here.
+  file1.ts:8:5
     8     duplicate7: () => string;
           ~~~~~~~~~~
-
+    'duplicate7' was also declared here.
 file2.ts:9:5 - error TS2300: Duplicate identifier 'duplicate8'.
 
 9     duplicate8(): number;
       ~~~~~~~~~~
 
-  file1.ts:9:5 - 'duplicate8' was also declared here.
+  file1.ts:9:5
     9     duplicate8: () => string;
           ~~~~~~~~~~
+    'duplicate8' was also declared here.
 
 
 ==== file1.ts (8 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans5.errors.txt b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans5.errors.txt
index 21f53eb8eb1a0..558c71feb3c30 100644
--- a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans5.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans5.errors.txt
@@ -3,54 +3,55 @@
 3         duplicate1: () => string;
           ~~~~~~~~~~
 
-  file2.ts:4:9 - 'duplicate1' was also declared here.
+  file2.ts:4:9
     4         duplicate1(): number;
               ~~~~~~~~~~
-
+    'duplicate1' was also declared here.
 file1.ts:4:9 - error TS2300: Duplicate identifier 'duplicate2'.
 
 4         duplicate2: () => string;
           ~~~~~~~~~~
 
-  file2.ts:5:9 - 'duplicate2' was also declared here.
+  file2.ts:5:9
     5         duplicate2(): number;
               ~~~~~~~~~~
-
+    'duplicate2' was also declared here.
 file1.ts:5:9 - error TS2300: Duplicate identifier 'duplicate3'.
 
 5         duplicate3: () => string;
           ~~~~~~~~~~
 
-  file2.ts:6:9 - 'duplicate3' was also declared here.
+  file2.ts:6:9
     6         duplicate3(): number;
               ~~~~~~~~~~
-
+    'duplicate3' was also declared here.
 file2.ts:4:9 - error TS2300: Duplicate identifier 'duplicate1'.
 
 4         duplicate1(): number;
           ~~~~~~~~~~
 
-  file1.ts:3:9 - 'duplicate1' was also declared here.
+  file1.ts:3:9
     3         duplicate1: () => string;
               ~~~~~~~~~~
-
+    'duplicate1' was also declared here.
 file2.ts:5:9 - error TS2300: Duplicate identifier 'duplicate2'.
 
 5         duplicate2(): number;
           ~~~~~~~~~~
 
-  file1.ts:4:9 - 'duplicate2' was also declared here.
+  file1.ts:4:9
     4         duplicate2: () => string;
               ~~~~~~~~~~
-
+    'duplicate2' was also declared here.
 file2.ts:6:9 - error TS2300: Duplicate identifier 'duplicate3'.
 
 6         duplicate3(): number;
           ~~~~~~~~~~
 
-  file1.ts:5:9 - 'duplicate3' was also declared here.
+  file1.ts:5:9
     5         duplicate3: () => string;
               ~~~~~~~~~~
+    'duplicate3' was also declared here.
 
 
 ==== file1.ts (3 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans6.errors.txt b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans6.errors.txt
index 3466d69b043ff..f0c25f2c3ebcc 100644
--- a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans6.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans6.errors.txt
@@ -3,54 +3,55 @@
 3         duplicate1: () => string;
           ~~~~~~~~~~
 
-  file2.ts:5:9 - 'duplicate1' was also declared here.
+  file2.ts:5:9
     5         duplicate1(): number;
               ~~~~~~~~~~
-
+    'duplicate1' was also declared here.
 file1.ts:4:9 - error TS2300: Duplicate identifier 'duplicate2'.
 
 4         duplicate2: () => string;
           ~~~~~~~~~~
 
-  file2.ts:6:9 - 'duplicate2' was also declared here.
+  file2.ts:6:9
     6         duplicate2(): number;
               ~~~~~~~~~~
-
+    'duplicate2' was also declared here.
 file1.ts:5:9 - error TS2300: Duplicate identifier 'duplicate3'.
 
 5         duplicate3: () => string;
           ~~~~~~~~~~
 
-  file2.ts:7:9 - 'duplicate3' was also declared here.
+  file2.ts:7:9
     7         duplicate3(): number;
               ~~~~~~~~~~
-
+    'duplicate3' was also declared here.
 file2.ts:5:9 - error TS2300: Duplicate identifier 'duplicate1'.
 
 5         duplicate1(): number;
           ~~~~~~~~~~
 
-  file1.ts:3:9 - 'duplicate1' was also declared here.
+  file1.ts:3:9
     3         duplicate1: () => string;
               ~~~~~~~~~~
-
+    'duplicate1' was also declared here.
 file2.ts:6:9 - error TS2300: Duplicate identifier 'duplicate2'.
 
 6         duplicate2(): number;
           ~~~~~~~~~~
 
-  file1.ts:4:9 - 'duplicate2' was also declared here.
+  file1.ts:4:9
     4         duplicate2: () => string;
               ~~~~~~~~~~
-
+    'duplicate2' was also declared here.
 file2.ts:7:9 - error TS2300: Duplicate identifier 'duplicate3'.
 
 7         duplicate3(): number;
           ~~~~~~~~~~
 
-  file1.ts:5:9 - 'duplicate3' was also declared here.
+  file1.ts:5:9
     5         duplicate3: () => string;
               ~~~~~~~~~~
+    'duplicate3' was also declared here.
 
 
 ==== file2.ts (3 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans7.errors.txt b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans7.errors.txt
index 9381fbbeed026..4025d50fba249 100644
--- a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans7.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans7.errors.txt
@@ -3,162 +3,163 @@
 3         duplicate1: () => string;
           ~~~~~~~~~~
 
-  file2.ts:5:9 - 'duplicate1' was also declared here.
+  file2.ts:5:9
     5         duplicate1(): number;
               ~~~~~~~~~~
-
+    'duplicate1' was also declared here.
 file1.ts:4:9 - error TS2300: Duplicate identifier 'duplicate2'.
 
 4         duplicate2: () => string;
           ~~~~~~~~~~
 
-  file2.ts:6:9 - 'duplicate2' was also declared here.
+  file2.ts:6:9
     6         duplicate2(): number;
               ~~~~~~~~~~
-
+    'duplicate2' was also declared here.
 file1.ts:5:9 - error TS2300: Duplicate identifier 'duplicate3'.
 
 5         duplicate3: () => string;
           ~~~~~~~~~~
 
-  file2.ts:7:9 - 'duplicate3' was also declared here.
+  file2.ts:7:9
     7         duplicate3(): number;
               ~~~~~~~~~~
-
+    'duplicate3' was also declared here.
 file1.ts:6:9 - error TS2300: Duplicate identifier 'duplicate4'.
 
 6         duplicate4: () => string;
           ~~~~~~~~~~
 
-  file2.ts:8:9 - 'duplicate4' was also declared here.
+  file2.ts:8:9
     8         duplicate4(): number;
               ~~~~~~~~~~
-
+    'duplicate4' was also declared here.
 file1.ts:7:9 - error TS2300: Duplicate identifier 'duplicate5'.
 
 7         duplicate5: () => string;
           ~~~~~~~~~~
 
-  file2.ts:9:9 - 'duplicate5' was also declared here.
+  file2.ts:9:9
     9         duplicate5(): number;
               ~~~~~~~~~~
-
+    'duplicate5' was also declared here.
 file1.ts:8:9 - error TS2300: Duplicate identifier 'duplicate6'.
 
 8         duplicate6: () => string;
           ~~~~~~~~~~
 
-  file2.ts:10:9 - 'duplicate6' was also declared here.
+  file2.ts:10:9
     10         duplicate6(): number;
                ~~~~~~~~~~
-
+    'duplicate6' was also declared here.
 file1.ts:9:9 - error TS2300: Duplicate identifier 'duplicate7'.
 
 9         duplicate7: () => string;
           ~~~~~~~~~~
 
-  file2.ts:11:9 - 'duplicate7' was also declared here.
+  file2.ts:11:9
     11         duplicate7(): number;
                ~~~~~~~~~~
-
+    'duplicate7' was also declared here.
 file1.ts:10:9 - error TS2300: Duplicate identifier 'duplicate8'.
 
 10         duplicate8: () => string;
            ~~~~~~~~~~
 
-  file2.ts:12:9 - 'duplicate8' was also declared here.
+  file2.ts:12:9
     12         duplicate8(): number;
                ~~~~~~~~~~
-
+    'duplicate8' was also declared here.
 file1.ts:11:9 - error TS2300: Duplicate identifier 'duplicate9'.
 
 11         duplicate9: () => string;
            ~~~~~~~~~~
 
-  file2.ts:13:9 - 'duplicate9' was also declared here.
+  file2.ts:13:9
     13         duplicate9(): number;
                ~~~~~~~~~~
-
+    'duplicate9' was also declared here.
 file2.ts:5:9 - error TS2300: Duplicate identifier 'duplicate1'.
 
 5         duplicate1(): number;
           ~~~~~~~~~~
 
-  file1.ts:3:9 - 'duplicate1' was also declared here.
+  file1.ts:3:9
     3         duplicate1: () => string;
               ~~~~~~~~~~
-
+    'duplicate1' was also declared here.
 file2.ts:6:9 - error TS2300: Duplicate identifier 'duplicate2'.
 
 6         duplicate2(): number;
           ~~~~~~~~~~
 
-  file1.ts:4:9 - 'duplicate2' was also declared here.
+  file1.ts:4:9
     4         duplicate2: () => string;
               ~~~~~~~~~~
-
+    'duplicate2' was also declared here.
 file2.ts:7:9 - error TS2300: Duplicate identifier 'duplicate3'.
 
 7         duplicate3(): number;
           ~~~~~~~~~~
 
-  file1.ts:5:9 - 'duplicate3' was also declared here.
+  file1.ts:5:9
     5         duplicate3: () => string;
               ~~~~~~~~~~
-
+    'duplicate3' was also declared here.
 file2.ts:8:9 - error TS2300: Duplicate identifier 'duplicate4'.
 
 8         duplicate4(): number;
           ~~~~~~~~~~
 
-  file1.ts:6:9 - 'duplicate4' was also declared here.
+  file1.ts:6:9
     6         duplicate4: () => string;
               ~~~~~~~~~~
-
+    'duplicate4' was also declared here.
 file2.ts:9:9 - error TS2300: Duplicate identifier 'duplicate5'.
 
 9         duplicate5(): number;
           ~~~~~~~~~~
 
-  file1.ts:7:9 - 'duplicate5' was also declared here.
+  file1.ts:7:9
     7         duplicate5: () => string;
               ~~~~~~~~~~
-
+    'duplicate5' was also declared here.
 file2.ts:10:9 - error TS2300: Duplicate identifier 'duplicate6'.
 
 10         duplicate6(): number;
            ~~~~~~~~~~
 
-  file1.ts:8:9 - 'duplicate6' was also declared here.
+  file1.ts:8:9
     8         duplicate6: () => string;
               ~~~~~~~~~~
-
+    'duplicate6' was also declared here.
 file2.ts:11:9 - error TS2300: Duplicate identifier 'duplicate7'.
 
 11         duplicate7(): number;
            ~~~~~~~~~~
 
-  file1.ts:9:9 - 'duplicate7' was also declared here.
+  file1.ts:9:9
     9         duplicate7: () => string;
               ~~~~~~~~~~
-
+    'duplicate7' was also declared here.
 file2.ts:12:9 - error TS2300: Duplicate identifier 'duplicate8'.
 
 12         duplicate8(): number;
            ~~~~~~~~~~
 
-  file1.ts:10:9 - 'duplicate8' was also declared here.
+  file1.ts:10:9
     10         duplicate8: () => string;
                ~~~~~~~~~~
-
+    'duplicate8' was also declared here.
 file2.ts:13:9 - error TS2300: Duplicate identifier 'duplicate9'.
 
 13         duplicate9(): number;
            ~~~~~~~~~~
 
-  file1.ts:11:9 - 'duplicate9' was also declared here.
+  file1.ts:11:9
     11         duplicate9: () => string;
                ~~~~~~~~~~
+    'duplicate9' was also declared here.
 
 
 ==== file2.ts (9 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/esModuleInteropPrettyErrorRelatedInformation.errors.txt b/tsc/testdata/baselines/reference/compiler/esModuleInteropPrettyErrorRelatedInformation.errors.txt
index 0fb5881599cf4..d17bb54d2aa2f 100644
--- a/tsc/testdata/baselines/reference/compiler/esModuleInteropPrettyErrorRelatedInformation.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/esModuleInteropPrettyErrorRelatedInformation.errors.txt
@@ -4,9 +4,10 @@
 3 invoke(foo);
          ~~~
 
-  index.ts:1:1 - Type originates at this import. A namespace-style import cannot be called or constructed, and will cause a failure at runtime. Consider using a default import or import require here instead.
+  index.ts:1:1
     1 import * as foo from "./foo";
       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+    Type originates at this import. A namespace-style import cannot be called or constructed, and will cause a failure at runtime. Consider using a default import or import require here instead.
 
 
 ==== foo.d.ts (0 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/manyCompilerErrorsInTheTwoFiles.errors.txt b/tsc/testdata/baselines/reference/compiler/manyCompilerErrorsInTheTwoFiles.errors.txt
index b7461fff03671..ca96d5ebf11b7 100644
--- a/tsc/testdata/baselines/reference/compiler/manyCompilerErrorsInTheTwoFiles.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/manyCompilerErrorsInTheTwoFiles.errors.txt
@@ -2,92 +2,74 @@
 
 1 const a =!@#!@$
              ~~
-
 a.ts:1:13 - error TS1134: Variable declaration expected.
 
 1 const a =!@#!@$
               ~
-
 a.ts:1:16 - error TS1109: Expression expected.
 
 1 const a =!@#!@$
                  ~
-
 a.ts:2:13 - error TS18026: '#!' can only be used at the start of a file.
 
 2 const b = !@#!@#!@#!
               ~~
-
 a.ts:2:14 - error TS1134: Variable declaration expected.
 
 2 const b = !@#!@#!@#!
                ~
-
 a.ts:2:16 - error TS18026: '#!' can only be used at the start of a file.
 
 2 const b = !@#!@#!@#!
                  ~~
-
 a.ts:2:19 - error TS18026: '#!' can only be used at the start of a file.
 
 2 const b = !@#!@#!@#!
                     ~~
-
 a.ts:3:1 - error TS2304: Cannot find name 'OK'.
 
 3 OK!
   ~~
-
 a.ts:4:1 - error TS1434: Unexpected keyword or identifier.
 
 4 HERE's A shouty thing
   ~~~~
-
 a.ts:4:1 - error TS2304: Cannot find name 'HERE'.
 
 4 HERE's A shouty thing
   ~~~~
-
 a.ts:4:22 - error TS1002: Unterminated string literal.
 
 4 HERE's A shouty thing
                        ~
-
 a.ts:5:1 - error TS1434: Unexpected keyword or identifier.
 
 5 GOTTA GO FAST
   ~~~~~
-
 a.ts:5:1 - error TS2304: Cannot find name 'GOTTA'.
 
 5 GOTTA GO FAST
   ~~~~~
-
 a.ts:5:7 - error TS1434: Unexpected keyword or identifier.
 
 5 GOTTA GO FAST
         ~~
-
 a.ts:5:7 - error TS2304: Cannot find name 'GO'.
 
 5 GOTTA GO FAST
         ~~
-
 a.ts:5:10 - error TS2304: Cannot find name 'FAST'.
 
 5 GOTTA GO FAST
            ~~~~
-
 b.ts:1:1 - error TS2304: Cannot find name 'fhqwhgads'.
 
 1 fhqwhgads
   ~~~~~~~~~
-
 b.ts:2:1 - error TS2304: Cannot find name 'to'.
 
 2 to
   ~~
-
 b.ts:3:1 - error TS2304: Cannot find name 'limit'.
 
 3 limit
diff --git a/tsc/testdata/baselines/reference/compiler/prettyContextNotDebugAssertion.errors.txt b/tsc/testdata/baselines/reference/compiler/prettyContextNotDebugAssertion.errors.txt
index 2c68ee24aa16d..7ed50695b4f32 100644
--- a/tsc/testdata/baselines/reference/compiler/prettyContextNotDebugAssertion.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/prettyContextNotDebugAssertion.errors.txt
@@ -3,9 +3,10 @@
 2 
   ~
 
-  index.ts:1:11 - The parser expected to find a '}' to match the '{' token here.
+  index.ts:1:11
     1 if (true) {
                 ~
+    The parser expected to find a '}' to match the '{' token here.
 
 
 ==== index.ts (1 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/prettyFileWithErrorsAndTabs.errors.txt b/tsc/testdata/baselines/reference/compiler/prettyFileWithErrorsAndTabs.errors.txt
index 810c38262b7cb..38509fcc0902d 100644
--- a/tsc/testdata/baselines/reference/compiler/prettyFileWithErrorsAndTabs.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/prettyFileWithErrorsAndTabs.errors.txt
@@ -2,12 +2,10 @@
 
 3   const x: string = 12;
           ~
-
 prettyFileWithErrorsAndTabs.ts:4:9 - error TS2322: Type 'number' is not assignable to type 'string'.
 
 4   const y: string = 12;
           ~
-
 prettyFileWithErrorsAndTabs.ts:5:9 - error TS2322: Type 'number' is not assignable to type 'string'.
 
 5   const z: string = 12;
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with json api.js
index 8add78656eff9..082733b22c032 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with json api.js	
@@ -31,4 +31,4 @@ TypeAcquisition::
 FileNames::
 /apath/a.ts,/apath/b.ts
 Errors::
-error TS17010: Unknown type acquisition option 'enableAutoDiscovy'.
+error TS17010: Unknown type acquisition option 'enableAutoDiscovy'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with jsonSourceFile api.js
index 97ac7deef094f..a2da4c1909bb9 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with jsonSourceFile api.js	
@@ -35,4 +35,3 @@ Errors::
 
 3   "enableAutoDiscovy": true,
     ~~~~~~~~~~~~~~~~~~~
-
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with json api.js
index d6e32be5ddbfe..ef39f5660ac17 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with json api.js	
@@ -25,4 +25,4 @@ TypeAcquisition::
 FileNames::
 /apath/a.ts,/apath/b.ts
 Errors::
-error TS17010: Unknown type acquisition option 'enableAutoDiscovy'.
+error TS17010: Unknown type acquisition option 'enableAutoDiscovy'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with jsonSourceFile api.js
index 5558dd2a1f1cb..e25a3467059d0 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with jsonSourceFile api.js	
@@ -29,4 +29,3 @@ Errors::
 
 3   "enableAutoDiscovy": true,
     ~~~~~~~~~~~~~~~~~~~
-
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with json api.js
index 385937b528ec2..cf7fe7917f062 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with json api.js	
@@ -11,4 +11,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with jsonSourceFile api.js
index 385937b528ec2..cf7fe7917f062 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with jsonSourceFile api.js	
@@ -11,4 +11,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with json api.js
index 10da1e28a9f93..f46c33ad62302 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with json api.js	
@@ -11,4 +11,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with jsonSourceFile api.js
index 10da1e28a9f93..f46c33ad62302 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with jsonSourceFile api.js	
@@ -11,4 +11,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with json api.js
index e290c4c786d60..2686b9c407aad 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with json api.js	
@@ -13,4 +13,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18002: The 'files' list in config file '/apath/tsconfig.json' is empty.
+error TS18002: The 'files' list in config file '/apath/tsconfig.json' is empty.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with jsonSourceFile api.js
index b3b115a909683..0db9e6e89e4d3 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with jsonSourceFile api.js	
@@ -17,4 +17,3 @@ Errors::
 
 2                 "files": [],
                            ~~
-
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with json api.js
index d6c070663e130..cf7944c9e280b 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with json api.js	
@@ -12,4 +12,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18002: The 'files' list in config file '/apath/tsconfig.json' is empty.
+error TS18002: The 'files' list in config file '/apath/tsconfig.json' is empty.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with jsonSourceFile api.js
index 51b3a5ec6f053..2649820a5bf7d 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with jsonSourceFile api.js	
@@ -16,4 +16,3 @@ Errors::
 
 2                 "files": []
                            ~~
-
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with json api.js
index 9b23e6b9e8585..1f0351e2dabe5 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with json api.js	
@@ -12,4 +12,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[]' and 'exclude' paths were '[]'.
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with jsonSourceFile api.js
index 9b23e6b9e8585..1f0351e2dabe5 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with jsonSourceFile api.js	
@@ -12,4 +12,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[]' and 'exclude' paths were '[]'.
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with json api.js
index 348ef1309a490..90013462152b5 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with json api.js	
@@ -13,4 +13,4 @@ FileNames::
 
 Errors::
 error TS5065: File specification cannot contain a parent directory ('..') that appears after a recursive directory wildcard ('**'): '**/../*.ts'.
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/../*.ts"]' and 'exclude' paths were '[]'.
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/../*.ts"]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with jsonSourceFile api.js
index fd1b7ee08c416..e70c343768f58 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with jsonSourceFile api.js	
@@ -16,5 +16,4 @@ Errors::
 
 2                 "include": ["**/../*.ts"]
                               ~~~~~~~~~~~~
-
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/../*.ts"]' and 'exclude' paths were '[]'.
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/../*.ts"]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with json api.js
index 6224f4c9e1c6c..6bfe4f41ed6f7 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with json api.js	
@@ -15,4 +15,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '["/apath"]'.
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '["/apath"]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with jsonSourceFile api.js
index 6224f4c9e1c6c..6bfe4f41ed6f7 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with jsonSourceFile api.js	
@@ -15,4 +15,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '["/apath"]'.
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '["/apath"]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with json api.js
index 687d07172e1c5..600f42a73c123 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with json api.js	
@@ -14,4 +14,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 /apath/a.ts
 Errors::
-error TS6266: Option 'help' can only be specified on command line.
+error TS6266: Option 'help' can only be specified on command line.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with jsonSourceFile api.js
index b33d215d5c225..c4968e277a0e8 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with jsonSourceFile api.js	
@@ -18,4 +18,3 @@ Errors::
 
 3     "help": true
       ~~~~~~
-
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with json api.js
index 862250c5c77e5..3c0c6e0806db4 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with json api.js	
@@ -19,4 +19,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS5024: Compiler option 'files' requires a value of type string.
+error TS5024: Compiler option 'files' requires a value of type string.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with jsonSourceFile api.js
index db8d6cd9d8c5a..6d7916c01e0a1 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with jsonSourceFile api.js	
@@ -30,4 +30,3 @@ Errors::
     ~~~~~~~
   8     }
     ~~~~~
-
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with json api.js
index 70c5e06e9eed9..16c08f98d6ef2 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with json api.js	
@@ -17,4 +17,4 @@ FileNames::
 
 Errors::
 error TS5024: Compiler option 'include' requires a value of type string.
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[["./**/*.ts"]]' and 'exclude' paths were '[]'.
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[["./**/*.ts"]]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with jsonSourceFile api.js
index b80ebe19dbb9d..c7202d0880dba 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with jsonSourceFile api.js	
@@ -24,5 +24,4 @@ Errors::
   ~~~~~~~~~~~~~~~~~
 5     ]
   ~~~~~
-
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[["./**/*.ts"]]' and 'exclude' paths were '[]'.
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[["./**/*.ts"]]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with json api.js
index d07c2c117ec84..bd5f035edcff4 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with json api.js	
@@ -14,4 +14,4 @@ configFileName:: tsconfig.json
 FileNames::
 /app.ts
 Errors::
-error TS5023: Unknown compiler option 'unknown'.
+error TS5023: Unknown compiler option 'unknown'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with jsonSourceFile api.js
index b076bb4ed9c79..9741d7f77e99d 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with jsonSourceFile api.js	
@@ -18,4 +18,3 @@ Errors::
 
 3     "unknown": true
       ~~~~~~~~~
-
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with json api.js
index fb63985a902e6..45bbfe8a2a669 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with json api.js	
@@ -40,4 +40,4 @@ Errors::
 error TS5025: Unknown compiler option 'nouncheckedsideeffectimports'. Did you mean 'noUncheckedSideEffectImports'?
 error TS5025: Unknown compiler option 'moduledetection'. Did you mean 'moduleDetection'?
 error TS5025: Unknown compiler option 'skiplibcheck'. Did you mean 'skipLibCheck'?
-error TS5025: Unknown compiler option 'checkjs'. Did you mean 'checkJs'?
+error TS5025: Unknown compiler option 'checkjs'. Did you mean 'checkJs'?
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with jsonSourceFile api.js
index b0719d4b7f4cf..e3e0b5592d815 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with jsonSourceFile api.js	
@@ -35,49 +35,39 @@ Errors::
 
 3     "sourcemap": true,
       ~~~~~~~~~~~
-
 tsconfig.json:4:5 - error TS5025: Unknown compiler option 'declarationmap'. Did you mean 'declarationMap'?
 
 4     "declarationmap": true,
       ~~~~~~~~~~~~~~~~
-
 tsconfig.json:5:5 - error TS5025: Unknown compiler option 'nouncheckedindexedaccess'. Did you mean 'noUncheckedIndexedAccess'?
 
 5     "nouncheckedindexedaccess": true,
       ~~~~~~~~~~~~~~~~~~~~~~~~~~
-
 tsconfig.json:6:5 - error TS5025: Unknown compiler option 'exactoptionalpropertytypes'. Did you mean 'exactOptionalPropertyTypes'?
 
 6     "exactoptionalpropertytypes": true,
       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
 tsconfig.json:7:5 - error TS5025: Unknown compiler option 'verbatimmodulesyntax'. Did you mean 'verbatimModuleSyntax'?
 
 7     "verbatimmodulesyntax": true,
       ~~~~~~~~~~~~~~~~~~~~~~
-
 tsconfig.json:8:5 - error TS5025: Unknown compiler option 'isolatedmodules'. Did you mean 'isolatedModules'?
 
 8     "isolatedmodules": true,
       ~~~~~~~~~~~~~~~~~
-
 tsconfig.json:9:5 - error TS5025: Unknown compiler option 'nouncheckedsideeffectimports'. Did you mean 'noUncheckedSideEffectImports'?
 
 9     "nouncheckedsideeffectimports": true,
       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
 tsconfig.json:10:5 - error TS5025: Unknown compiler option 'moduledetection'. Did you mean 'moduleDetection'?
 
 10     "moduledetection": "force",
        ~~~~~~~~~~~~~~~~~
-
 tsconfig.json:11:5 - error TS5025: Unknown compiler option 'skiplibcheck'. Did you mean 'skipLibCheck'?
 
 11     "skiplibcheck": true,
        ~~~~~~~~~~~~~~
-
 tsconfig.json:12:5 - error TS5025: Unknown compiler option 'checkjs'. Did you mean 'checkJs'?
 
 12     "checkjs": true
        ~~~~~~~~~
-
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with json api.js
index 9ad898f4d6399..5c3e71d5b20a1 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with json api.js	
@@ -18,4 +18,4 @@ FileNames::
 Errors::
 error TS6046: Argument for '--target' option must be: 'es6', 'es2015', 'es2016', 'es2017', 'es2018', 'es2019', 'es2020', 'es2021', 'es2022', 'es2023', 'es2024', 'es2025', 'esnext'.
 error TS5024: Compiler option 'removeComments' requires a value of type boolean.
-error TS6046: Argument for '--moduleResolution' option must be: 'node16', 'nodenext', 'bundler'.
+error TS6046: Argument for '--moduleResolution' option must be: 'node16', 'nodenext', 'bundler'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with jsonSourceFile api.js
index a32648be78659..d20dc3e2f0575 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with jsonSourceFile api.js	
@@ -20,14 +20,11 @@ Errors::
 
 3     "target": "invalid value",
                 ~~~~~~~~~~~~~~~
-
 tsconfig.json:4:23 - error TS5024: Compiler option 'removeComments' requires a value of type boolean.
 
 4     "removeComments": "should be a boolean",
                         ~~~~~~~~~~~~~~~~~~~~~
-
 tsconfig.json:5:25 - error TS6046: Argument for '--moduleResolution' option must be: 'node16', 'nodenext', 'bundler'.
 
 5     "moduleResolution": "invalid value"
                           ~~~~~~~~~~~~~~~
-
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with json api.js
index b79c50099efe3..9991b2ef71eb0 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with json api.js	
@@ -14,4 +14,4 @@ configFileName:: tsconfig.json
 FileNames::
 /app.ts
 Errors::
-error TS5025: Unknown compiler option 'targt'. Did you mean 'target'?
+error TS5025: Unknown compiler option 'targt'. Did you mean 'target'?
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with jsonSourceFile api.js
index 882a1f6ce8a81..8159111918760 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with jsonSourceFile api.js	
@@ -18,4 +18,3 @@ Errors::
 
 3     "targt": 1
       ~~~~~~~
-
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with json api.js
index f1ec52ed93f99..087df87cdbb43 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with json api.js	
@@ -20,4 +20,4 @@ configFileName:: tsconfig.json
 FileNames::
 /apath/foge.ts,/apath/test.ts
 Errors::
-error TS6114: Unknown option 'excludes'. Did you mean 'exclude'?
+error TS6114: Unknown option 'excludes'. Did you mean 'exclude'?
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with jsonSourceFile api.js
index 7e0de849d67b8..f308c3fe49528 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with jsonSourceFile api.js	
@@ -24,4 +24,3 @@ Errors::
 
 5                     "excludes": [
                       ~~~~~~~~~~
-
diff --git a/tsc/testdata/baselines/reference/conformance/typedefCrossModule5.errors.txt b/tsc/testdata/baselines/reference/conformance/typedefCrossModule5.errors.txt
index 748c5510b8d78..d557f9ab1eb76 100644
--- a/tsc/testdata/baselines/reference/conformance/typedefCrossModule5.errors.txt
+++ b/tsc/testdata/baselines/reference/conformance/typedefCrossModule5.errors.txt
@@ -3,36 +3,37 @@
 1 /** @typedef {number} Foo */
                         ~~~
 
-  mod2.js:1:7 - 'Foo' was also declared here.
+  mod2.js:1:7
     1 class Foo { } // should error
             ~~~
-
+    'Foo' was also declared here.
 mod1.js:2:7 - error TS2451: Cannot redeclare block-scoped variable 'Bar'.
 
 2 class Bar {}
         ~~~
 
-  mod2.js:2:7 - 'Bar' was also declared here.
+  mod2.js:2:7
     2 const Bar = 3;
             ~~~
-
+    'Bar' was also declared here.
 mod2.js:1:7 - error TS2300: Duplicate identifier 'Foo'.
 
 1 class Foo { } // should error
         ~~~
 
-  mod1.js:1:23 - 'Foo' was also declared here.
+  mod1.js:1:23
     1 /** @typedef {number} Foo */
                             ~~~
-
+    'Foo' was also declared here.
 mod2.js:2:7 - error TS2451: Cannot redeclare block-scoped variable 'Bar'.
 
 2 const Bar = 3;
         ~~~
 
-  mod1.js:2:7 - 'Bar' was also declared here.
+  mod1.js:2:7
     2 class Bar {}
             ~~~
+    'Bar' was also declared here.
 
 
 ==== mod1.js (2 errors) ====
diff --git a/tsc/testdata/baselines/reference/tsbuild/commandLine/bad-locale.js b/tsc/testdata/baselines/reference/tsbuild/commandLine/bad-locale.js
index f85b09a8f91b0..41ce42d0822cf 100644
--- a/tsc/testdata/baselines/reference/tsbuild/commandLine/bad-locale.js
+++ b/tsc/testdata/baselines/reference/tsbuild/commandLine/bad-locale.js
@@ -7,3 +7,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS6048: Locale must be an IETF BCP 47 language tag. Examples: 'en', 'ja-jp'.
 
+
diff --git a/tsc/testdata/baselines/reference/tsbuild/commandLine/when-build-not-first-argument.js b/tsc/testdata/baselines/reference/tsbuild/commandLine/when-build-not-first-argument.js
index d44964311b2eb..1b6af49f54f0d 100644
--- a/tsc/testdata/baselines/reference/tsbuild/commandLine/when-build-not-first-argument.js
+++ b/tsc/testdata/baselines/reference/tsbuild/commandLine/when-build-not-first-argument.js
@@ -6,5 +6,7 @@ tsgo --verbose --build
 ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5093: Compiler option '--verbose' may only be used with '--build'.
+
 error TS6369: Option '--build' must be the first command line argument.
 
+
diff --git a/tsc/testdata/baselines/reference/tsbuild/configFileErrors/missing-config-file.js b/tsc/testdata/baselines/reference/tsbuild/configFileErrors/missing-config-file.js
index c194821e7e3a0..8d1d180950b1c 100644
--- a/tsc/testdata/baselines/reference/tsbuild/configFileErrors/missing-config-file.js
+++ b/tsc/testdata/baselines/reference/tsbuild/configFileErrors/missing-config-file.js
@@ -7,6 +7,7 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS6053: File '/home/src/workspaces/project/bogus.json' not found.
 
+
 Found 1 error.
 
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/configFileErrors/when-tsconfig-extends-the-missing-file.js b/tsc/testdata/baselines/reference/tsbuild/configFileErrors/when-tsconfig-extends-the-missing-file.js
index 04120bd116f8a..83ba10640a7b8 100644
--- a/tsc/testdata/baselines/reference/tsbuild/configFileErrors/when-tsconfig-extends-the-missing-file.js
+++ b/tsc/testdata/baselines/reference/tsbuild/configFileErrors/when-tsconfig-extends-the-missing-file.js
@@ -30,10 +30,14 @@ tsgo --b
 ExitStatus:: DiagnosticsPresent_OutputsGenerated
 Output::
 error TS5083: Cannot read file '/home/src/workspaces/project/foobar.json'.
+
 error TS18003: No inputs were found in config file '/home/src/workspaces/project/tsconfig.first.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
+
 error TS5083: Cannot read file '/home/src/workspaces/project/foobar.json'.
+
 error TS18003: No inputs were found in config file '/home/src/workspaces/project/tsconfig.second.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
 
+
 Found 4 errors.
 
 //// [/home/src/workspaces/project/tsconfig.first.tsbuildinfo] *new* 
diff --git a/tsc/testdata/baselines/reference/tsbuild/demo/in-circular-branch-reports-the-error-about-it-by-stopping-build.js b/tsc/testdata/baselines/reference/tsbuild/demo/in-circular-branch-reports-the-error-about-it-by-stopping-build.js
index 6753102212018..bcc735c0c26b2 100644
--- a/tsc/testdata/baselines/reference/tsbuild/demo/in-circular-branch-reports-the-error-about-it-by-stopping-build.js
+++ b/tsc/testdata/baselines/reference/tsbuild/demo/in-circular-branch-reports-the-error-about-it-by-stopping-build.js
@@ -128,6 +128,7 @@ Output::
 /user/username/projects/demo/zoo/tsconfig.json
 /user/username/projects/demo/animals/tsconfig.json
 
+
 Found 1 error.
 
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/noCheck/dts-errors-with-incremental.js b/tsc/testdata/baselines/reference/tsbuild/noCheck/dts-errors-with-incremental.js
index bbb460196c3bb..7317ea74d8899 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noCheck/dts-errors-with-incremental.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noCheck/dts-errors-with-incremental.js
@@ -28,9 +28,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -189,9 +190,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -446,9 +448,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -579,9 +582,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -610,9 +614,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -1040,9 +1045,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsbuild/noCheck/dts-errors.js b/tsc/testdata/baselines/reference/tsbuild/noCheck/dts-errors.js
index a1c925662626e..be71f7f25d0e0 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noCheck/dts-errors.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noCheck/dts-errors.js
@@ -28,9 +28,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Updating unchanged output timestamps of project 'tsconfig.json'...
 
@@ -120,9 +121,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Updating unchanged output timestamps of project 'tsconfig.json'...
 
@@ -300,9 +302,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Updating unchanged output timestamps of project 'tsconfig.json'...
 
@@ -366,9 +369,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Updating unchanged output timestamps of project 'tsconfig.json'...
 
@@ -407,9 +411,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Updating unchanged output timestamps of project 'tsconfig.json'...
 
@@ -637,9 +642,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Updating unchanged output timestamps of project 'tsconfig.json'...
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-composite.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-composite.js
index 5e30488659633..2a5ed7dde09e7 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-composite.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-composite.js
@@ -365,18 +365,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -980,18 +982,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1262,18 +1266,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1311,18 +1317,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1360,18 +1368,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1409,18 +1419,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-incremental-declaration.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-incremental-declaration.js
index edc7612baca6a..d9ca79fa2b2a7 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-incremental-declaration.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-incremental-declaration.js
@@ -364,18 +364,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -955,18 +957,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1239,18 +1243,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1288,18 +1294,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1337,18 +1345,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1386,18 +1396,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-incremental.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-incremental.js
index 44116bd52c4a7..d8b3a3979c423 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-incremental.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-incremental.js
@@ -306,18 +306,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -873,18 +875,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1130,18 +1134,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1179,18 +1185,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1228,18 +1236,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1277,18 +1287,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-composite.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-composite.js
index 90722985262a1..5b4df4b9c1042 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-composite.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-composite.js
@@ -524,18 +524,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-incremental-declaration.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-incremental-declaration.js
index 2ee26d6b550a1..2ce86dff240ed 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-incremental-declaration.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-incremental-declaration.js
@@ -497,18 +497,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-incremental.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-incremental.js
index ebf7151afa8a1..c3d8097f3cb78 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-incremental.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-incremental.js
@@ -436,18 +436,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-incremental-as-modules.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-incremental-as-modules.js
index f3f845431f1d5..e937dbec56714 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-incremental-as-modules.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-incremental-as-modules.js
@@ -146,9 +146,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -276,9 +277,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -420,9 +422,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-incremental.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-incremental.js
index d104050739f79..490e73f31cccf 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-incremental.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-incremental.js
@@ -133,9 +133,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -250,9 +251,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -381,9 +383,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-multiple-files.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-multiple-files.js
index b4897da99ae1f..5ccc29291276d 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-multiple-files.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-multiple-files.js
@@ -178,27 +178,30 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 c.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14 - Add a type annotation to the variable c.
+  c.ts:1:14
     1 export const c = class { private p = 10; };
                    ~
+    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14 - Add a type annotation to the variable d.
+  d.ts:1:14
     1 export const d = class { private p = 10; };
                    ~
+    Add a type annotation to the variable d.
 
 
 Found 3 errors in 3 files.
@@ -417,27 +420,30 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 c.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14 - Add a type annotation to the variable c.
+  c.ts:1:14
     1 export const c = class { private p = 10; };
                    ~
+    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14 - Add a type annotation to the variable d.
+  d.ts:1:14
     1 export const d = class { private p = 10; };
                    ~
+    Add a type annotation to the variable d.
 
 
 Found 3 errors in 3 files.
@@ -670,27 +676,30 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 c.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14 - Add a type annotation to the variable c.
+  c.ts:1:14
     1 export const c = class { private p = 10; };
                    ~
+    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14 - Add a type annotation to the variable d.
+  d.ts:1:14
     1 export const d = class { private p = 10; };
                    ~
+    Add a type annotation to the variable d.
 
 
 Found 3 errors in 3 files.
@@ -1063,18 +1072,20 @@ Output::
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14 - Add a type annotation to the variable c.
+  c.ts:1:14
     1 export const c = class { private p = 10; };
                    ~
+    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14 - Add a type annotation to the variable d.
+  d.ts:1:14
     1 export const d = class { private p = 10; };
                    ~
+    Add a type annotation to the variable d.
 
 
 Found 2 errors in 2 files.
@@ -1275,18 +1286,20 @@ Output::
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14 - Add a type annotation to the variable c.
+  c.ts:1:14
     1 export const c = class { private p = 10; };
                    ~
+    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14 - Add a type annotation to the variable d.
+  d.ts:1:14
     1 export const d = class { private p = 10; };
                    ~
+    Add a type annotation to the variable d.
 
 
 Found 2 errors in 2 files.
@@ -1490,9 +1503,10 @@ Output::
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14 - Add a type annotation to the variable d.
+  d.ts:1:14
     1 export const d = class { private p = 10; };
                    ~
+    Add a type annotation to the variable d.
 
 
 Found 1 error in d.ts:1
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes.js
index 58527768b2b86..bd48227f7755d 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes.js
@@ -105,9 +105,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -153,9 +154,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -222,9 +224,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Updating unchanged output timestamps of project 'tsconfig.json'...
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-incremental-as-modules.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-incremental-as-modules.js
index dd20817117c4a..72f5632b7fcf2 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-incremental-as-modules.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-incremental-as-modules.js
@@ -28,9 +28,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -184,9 +185,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -434,9 +436,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -581,9 +584,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -713,9 +717,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-incremental.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-incremental.js
index c719ef150f4d8..d9506c4bd6a3f 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-incremental.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-incremental.js
@@ -26,9 +26,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -168,9 +169,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -382,9 +384,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -503,9 +506,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -617,9 +621,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors.js
index 6ea5a365d78c4..d2addd198b59f 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors.js
@@ -26,9 +26,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -97,9 +98,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -234,9 +236,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -282,9 +285,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Updating unchanged output timestamps of project 'tsconfig.json'...
 
@@ -325,9 +329,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmitOnError/dts-errors-with-declaration-with-incremental.js b/tsc/testdata/baselines/reference/tsbuild/noEmitOnError/dts-errors-with-declaration-with-incremental.js
index 80bca24844738..e3e9765a8d774 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmitOnError/dts-errors-with-declaration-with-incremental.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmitOnError/dts-errors-with-declaration-with-incremental.js
@@ -36,9 +36,10 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14 - Add a type annotation to the variable a.
+  src/main.ts:2:14
     2 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in src/main.ts:2
@@ -221,9 +222,10 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14 - Add a type annotation to the variable a.
+  src/main.ts:2:14
     2 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in src/main.ts:2
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmitOnError/dts-errors-with-declaration.js b/tsc/testdata/baselines/reference/tsbuild/noEmitOnError/dts-errors-with-declaration.js
index 1c5fe2ab6db76..8615949e8e748 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmitOnError/dts-errors-with-declaration.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmitOnError/dts-errors-with-declaration.js
@@ -36,9 +36,10 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14 - Add a type annotation to the variable a.
+  src/main.ts:2:14
     2 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in src/main.ts:2
@@ -121,9 +122,10 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14 - Add a type annotation to the variable a.
+  src/main.ts:2:14
     2 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in src/main.ts:2
diff --git a/tsc/testdata/baselines/reference/tsbuild/outputPaths/when-rootDir-is-specified-but-not-all-files-belong-to-rootDir-and-is-composite.js b/tsc/testdata/baselines/reference/tsbuild/outputPaths/when-rootDir-is-specified-but-not-all-files-belong-to-rootDir-and-is-composite.js
index 64dfdb89976d2..2ae7a6dece635 100644
--- a/tsc/testdata/baselines/reference/tsbuild/outputPaths/when-rootDir-is-specified-but-not-all-files-belong-to-rootDir-and-is-composite.js
+++ b/tsc/testdata/baselines/reference/tsbuild/outputPaths/when-rootDir-is-specified-but-not-all-files-belong-to-rootDir-and-is-composite.js
@@ -28,6 +28,7 @@ Output::
   The file is in the program because:
     Matched by default include pattern '**/*'
 
+
 Found 1 error.
 
 //// [/home/src/tslibs/TS/Lib/lib.es2025.full.d.ts] *Lib*
@@ -164,6 +165,7 @@ Output::
   The file is in the program because:
     Matched by default include pattern '**/*'
 
+
 Found 1 error.
 
 
@@ -184,6 +186,7 @@ Output::
   The file is in the program because:
     Matched by default include pattern '**/*'
 
+
 Found 1 error.
 
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/outputPaths/when-rootDir-is-specified-but-not-all-files-belong-to-rootDir.js b/tsc/testdata/baselines/reference/tsbuild/outputPaths/when-rootDir-is-specified-but-not-all-files-belong-to-rootDir.js
index ef89e37d1413c..fb88da9a58094 100644
--- a/tsc/testdata/baselines/reference/tsbuild/outputPaths/when-rootDir-is-specified-but-not-all-files-belong-to-rootDir.js
+++ b/tsc/testdata/baselines/reference/tsbuild/outputPaths/when-rootDir-is-specified-but-not-all-files-belong-to-rootDir.js
@@ -27,6 +27,7 @@ Output::
   The file is in the program because:
     Matched by default include pattern '**/*'
 
+
 Found 1 error.
 
 //// [/home/src/tslibs/TS/Lib/lib.es2025.full.d.ts] *Lib*
@@ -105,6 +106,7 @@ Output::
   The file is in the program because:
     Matched by default include pattern '**/*'
 
+
 Found 1 error.
 
 //// [/home/src/workspaces/project/dist/index.js] *rewrite with same content*
@@ -129,6 +131,7 @@ Output::
   The file is in the program because:
     Matched by default include pattern '**/*'
 
+
 Found 1 error.
 
 //// [/home/src/workspaces/project/dist/index.js] *rewrite with same content*
diff --git a/tsc/testdata/baselines/reference/tsbuild/resolveJsonModule/importing-json-module-from-project-reference.js b/tsc/testdata/baselines/reference/tsbuild/resolveJsonModule/importing-json-module-from-project-reference.js
index 91ded68a14bbe..fe10e5b98a911 100644
--- a/tsc/testdata/baselines/reference/tsbuild/resolveJsonModule/importing-json-module-from-project-reference.js
+++ b/tsc/testdata/baselines/reference/tsbuild/resolveJsonModule/importing-json-module-from-project-reference.js
@@ -55,6 +55,7 @@ Output::
 [HH:MM:SS AM] Building project 'project/strings/tsconfig.json'...
 
 error TS5108: Option 'target=ES5' has been removed. Please remove it from your configuration.
+
 ../../tslibs/TS/Lib/lib.d.ts
    Default library for target 'ES5'
 project/strings/foo.json
@@ -64,6 +65,7 @@ project/strings/foo.json
 [HH:MM:SS AM] Building project 'project/main/tsconfig.json'...
 
 error TS5108: Option 'target=ES5' has been removed. Please remove it from your configuration.
+
 ../../tslibs/TS/Lib/lib.d.ts
    Default library for target 'ES5'
 project/strings/foo.json
@@ -270,6 +272,7 @@ Output::
 [HH:MM:SS AM] Building project 'project/strings/tsconfig.json'...
 
 error TS5108: Option 'target=ES5' has been removed. Please remove it from your configuration.
+
 ../../tslibs/TS/Lib/lib.d.ts
    Default library for target 'ES5'
 project/strings/foo.json
@@ -279,6 +282,7 @@ project/strings/foo.json
 [HH:MM:SS AM] Building project 'project/main/tsconfig.json'...
 
 error TS5108: Option 'target=ES5' has been removed. Please remove it from your configuration.
+
 ../../tslibs/TS/Lib/lib.d.ts
    Default library for target 'ES5'
 project/strings/foo.json
diff --git a/tsc/testdata/baselines/reference/tsbuild/sample/building-project-in-not-build-order-doesnt-throw-error.js b/tsc/testdata/baselines/reference/tsbuild/sample/building-project-in-not-build-order-doesnt-throw-error.js
index bda501271aebb..89bf911460ba4 100644
--- a/tsc/testdata/baselines/reference/tsbuild/sample/building-project-in-not-build-order-doesnt-throw-error.js
+++ b/tsc/testdata/baselines/reference/tsbuild/sample/building-project-in-not-build-order-doesnt-throw-error.js
@@ -70,6 +70,7 @@ Output::
 
 error TS6053: File '/user/username/projects/sample1/logic2/tsconfig.json' not found.
 
+
 Found 1 error.
 
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/sample/cleaning-project-in-not-build-order-doesnt-throw-error.js b/tsc/testdata/baselines/reference/tsbuild/sample/cleaning-project-in-not-build-order-doesnt-throw-error.js
index 5a1bbd8d55785..cd0e6fb6b413b 100644
--- a/tsc/testdata/baselines/reference/tsbuild/sample/cleaning-project-in-not-build-order-doesnt-throw-error.js
+++ b/tsc/testdata/baselines/reference/tsbuild/sample/cleaning-project-in-not-build-order-doesnt-throw-error.js
@@ -65,6 +65,7 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS6053: File '/user/username/projects/sample1/logic2/tsconfig.json' not found.
 
+
 Found 1 error.
 
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/sample/reports-error-if-input-file-is-missing-with-force.js b/tsc/testdata/baselines/reference/tsbuild/sample/reports-error-if-input-file-is-missing-with-force.js
index aca525d206f64..14cdedc21f3a1 100644
--- a/tsc/testdata/baselines/reference/tsbuild/sample/reports-error-if-input-file-is-missing-with-force.js
+++ b/tsc/testdata/baselines/reference/tsbuild/sample/reports-error-if-input-file-is-missing-with-force.js
@@ -69,9 +69,11 @@ Output::
 error TS6053: File '/user/username/projects/sample1/core/anotherModule.ts' not found.
   The file is in the program because:
     Part of 'files' list in tsconfig.json
-  core/tsconfig.json:3:16 - File is matched by 'files' list specified here.
+
+  core/tsconfig.json:3:16
     3      "files": ["anotherModule.ts", "index.ts", "some_decl.d.ts"],
                      ~~~~~~~~~~~~~~~~~~
+    File is matched by 'files' list specified here.
 
 [HH:MM:SS AM] Project 'logic/tsconfig.json' is being forcibly rebuilt
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/sample/reports-error-if-input-file-is-missing.js b/tsc/testdata/baselines/reference/tsbuild/sample/reports-error-if-input-file-is-missing.js
index 48909bacf674f..81f11be9100b8 100644
--- a/tsc/testdata/baselines/reference/tsbuild/sample/reports-error-if-input-file-is-missing.js
+++ b/tsc/testdata/baselines/reference/tsbuild/sample/reports-error-if-input-file-is-missing.js
@@ -69,9 +69,11 @@ Output::
 error TS6053: File '/user/username/projects/sample1/core/anotherModule.ts' not found.
   The file is in the program because:
     Part of 'files' list in tsconfig.json
-  core/tsconfig.json:3:16 - File is matched by 'files' list specified here.
+
+  core/tsconfig.json:3:16
     3      "files": ["anotherModule.ts", "index.ts", "some_decl.d.ts"],
                      ~~~~~~~~~~~~~~~~~~
+    File is matched by 'files' list specified here.
 
 [HH:MM:SS AM] Project 'logic/tsconfig.json' is out of date because output file 'logic/tsconfig.tsbuildinfo' does not exist
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors-when-test-does-not-reference-core.js b/tsc/testdata/baselines/reference/tsbuild/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors-when-test-does-not-reference-core.js
index 3ea7785e80104..5a9d28fca3d8d 100644
--- a/tsc/testdata/baselines/reference/tsbuild/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors-when-test-does-not-reference-core.js
+++ b/tsc/testdata/baselines/reference/tsbuild/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors-when-test-does-not-reference-core.js
@@ -76,9 +76,10 @@ Output::
 3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                                                   ~~~~~~~~
 
-  core/index.ts:3:26 - An argument for 'a' was not provided.
+  core/index.ts:3:26
     3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                ~~~~~~~~~
+    An argument for 'a' was not provided.
 
 [HH:MM:SS AM] Project 'logic/tsconfig.json' can't be built because its dependency 'core' has errors
 
@@ -277,9 +278,10 @@ Output::
 3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                                                   ~~~~~~~~
 
-  core/index.ts:3:26 - An argument for 'a' was not provided.
+  core/index.ts:3:26
     3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                ~~~~~~~~~
+    An argument for 'a' was not provided.
 
 [HH:MM:SS AM] Project 'logic/tsconfig.json' can't be built because its dependency 'core' has errors
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors.js b/tsc/testdata/baselines/reference/tsbuild/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors.js
index f8439919cb630..83989c3f96c1c 100644
--- a/tsc/testdata/baselines/reference/tsbuild/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors.js
+++ b/tsc/testdata/baselines/reference/tsbuild/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors.js
@@ -77,9 +77,10 @@ Output::
 3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                                                   ~~~~~~~~
 
-  core/index.ts:3:26 - An argument for 'a' was not provided.
+  core/index.ts:3:26
     3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                ~~~~~~~~~
+    An argument for 'a' was not provided.
 
 [HH:MM:SS AM] Project 'logic/tsconfig.json' can't be built because its dependency 'core' has errors
 
@@ -278,9 +279,10 @@ Output::
 3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                                                   ~~~~~~~~
 
-  core/index.ts:3:26 - An argument for 'a' was not provided.
+  core/index.ts:3:26
     3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                ~~~~~~~~~
+    An argument for 'a' was not provided.
 
 [HH:MM:SS AM] Project 'logic/tsconfig.json' can't be built because its dependency 'core' has errors
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/demo/updates-with-circular-reference.js b/tsc/testdata/baselines/reference/tsbuildWatch/demo/updates-with-circular-reference.js
index 0ff2c58725af6..f05ffcbbf76a3 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/demo/updates-with-circular-reference.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/demo/updates-with-circular-reference.js
@@ -129,6 +129,7 @@ Output::
 /user/username/projects/demo/core/tsconfig.json
 /user/username/projects/demo/zoo/tsconfig.json
 /user/username/projects/demo/animals/tsconfig.json
+
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors-with-incremental-as-modules.js b/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors-with-incremental-as-modules.js
index 265f254afb9fe..c020d1d30f47e 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors-with-incremental-as-modules.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors-with-incremental-as-modules.js
@@ -30,9 +30,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -440,9 +441,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -598,9 +600,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -741,9 +744,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors-with-incremental.js b/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors-with-incremental.js
index 5f8d8bba4132d..039461c4ad11d 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors-with-incremental.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors-with-incremental.js
@@ -28,9 +28,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -388,9 +389,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -520,9 +522,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -645,9 +648,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors.js b/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors.js
index 78428c9996a7f..fc71aa91ec852 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors.js
@@ -28,9 +28,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -224,9 +225,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -282,9 +284,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Updating unchanged output timestamps of project 'tsconfig.json'...
 
@@ -335,9 +338,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/noEmitOnError/noEmitOnError-with-declaration-with-incremental.js b/tsc/testdata/baselines/reference/tsbuildWatch/noEmitOnError/noEmitOnError-with-declaration-with-incremental.js
index 167a5b6ded6e4..9c69b168009c3 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/noEmitOnError/noEmitOnError-with-declaration-with-incremental.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/noEmitOnError/noEmitOnError-with-declaration-with-incremental.js
@@ -731,9 +731,10 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14 - Add a type annotation to the variable a.
+  src/main.ts:2:14
     2 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -895,9 +896,10 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14 - Add a type annotation to the variable a.
+  src/main.ts:2:14
     2 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/noEmitOnError/noEmitOnError-with-declaration.js b/tsc/testdata/baselines/reference/tsbuildWatch/noEmitOnError/noEmitOnError-with-declaration.js
index 430db82e70af3..0071c86b73b50 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/noEmitOnError/noEmitOnError-with-declaration.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/noEmitOnError/noEmitOnError-with-declaration.js
@@ -488,9 +488,10 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14 - Add a type annotation to the variable a.
+  src/main.ts:2:14
     2 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -554,9 +555,10 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14 - Add a type annotation to the variable a.
+  src/main.ts:2:14
     2 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-introduceError-when-file-with-no-error-changes.js b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-introduceError-when-file-with-no-error-changes.js
index c29ff1a88a093..2398fd6998e06 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-introduceError-when-file-with-no-error-changes.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-introduceError-when-file-with-no-error-changes.js
@@ -161,9 +161,10 @@ Output::
 1 export var myClassWithError = class {
              ~~~~~~~~~~~~~~~~
 
-  app/fileWithError.ts:1:12 - Add a type annotation to the variable myClassWithError.
+  app/fileWithError.ts:1:12
     1 export var myClassWithError = class {
                  ~~~~~~~~~~~~~~~~
+    Add a type annotation to the variable myClassWithError.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -302,9 +303,10 @@ Output::
 1 export var myClassWithError = class {
              ~~~~~~~~~~~~~~~~
 
-  app/fileWithError.ts:1:12 - Add a type annotation to the variable myClassWithError.
+  app/fileWithError.ts:1:12
     1 export var myClassWithError = class {
                  ~~~~~~~~~~~~~~~~
+    Add a type annotation to the variable myClassWithError.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-introduceError-when-fixing-errors-only-changed-file-is-emitted.js b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-introduceError-when-fixing-errors-only-changed-file-is-emitted.js
index 27e5d2018aeb8..f8fb35d19a78b 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-introduceError-when-fixing-errors-only-changed-file-is-emitted.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-introduceError-when-fixing-errors-only-changed-file-is-emitted.js
@@ -161,9 +161,10 @@ Output::
 1 export var myClassWithError = class {
              ~~~~~~~~~~~~~~~~
 
-  app/fileWithError.ts:1:12 - Add a type annotation to the variable myClassWithError.
+  app/fileWithError.ts:1:12
     1 export var myClassWithError = class {
                  ~~~~~~~~~~~~~~~~
+    Add a type annotation to the variable myClassWithError.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-when-file-with-no-error-changes.js b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-when-file-with-no-error-changes.js
index 7d854c571330c..b19de72392db6 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-when-file-with-no-error-changes.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-when-file-with-no-error-changes.js
@@ -25,9 +25,10 @@ Output::
 1 export var myClassWithError = class {
              ~~~~~~~~~~~~~~~~
 
-  app/fileWithError.ts:1:12 - Add a type annotation to the variable myClassWithError.
+  app/fileWithError.ts:1:12
     1 export var myClassWithError = class {
                  ~~~~~~~~~~~~~~~~
+    Add a type annotation to the variable myClassWithError.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -190,9 +191,10 @@ Output::
 1 export var myClassWithError = class {
              ~~~~~~~~~~~~~~~~
 
-  app/fileWithError.ts:1:12 - Add a type annotation to the variable myClassWithError.
+  app/fileWithError.ts:1:12
     1 export var myClassWithError = class {
                  ~~~~~~~~~~~~~~~~
+    Add a type annotation to the variable myClassWithError.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-when-fixing-error-files-all-files-are-emitted.js b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-when-fixing-error-files-all-files-are-emitted.js
index d99e8d2345cda..d314748adb740 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-when-fixing-error-files-all-files-are-emitted.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-when-fixing-error-files-all-files-are-emitted.js
@@ -25,9 +25,10 @@ Output::
 1 export var myClassWithError = class {
              ~~~~~~~~~~~~~~~~
 
-  app/fileWithError.ts:1:12 - Add a type annotation to the variable myClassWithError.
+  app/fileWithError.ts:1:12
     1 export var myClassWithError = class {
                  ~~~~~~~~~~~~~~~~
+    Add a type annotation to the variable myClassWithError.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/when-referenced-project-change-introduces-error-in-the-down-stream-project-and-then-fixes-it.js b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/when-referenced-project-change-introduces-error-in-the-down-stream-project-and-then-fixes-it.js
index cfba79d6835b6..d53e0620d4ed5 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/when-referenced-project-change-introduces-error-in-the-down-stream-project-and-then-fixes-it.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/when-referenced-project-change-introduces-error-in-the-down-stream-project-and-then-fixes-it.js
@@ -183,9 +183,10 @@ Output::
 2 createSomeObject().message;
                      ~~~~~~~
 
-  Library/library.d.ts:2:5 - 'message2' is declared here.
+  Library/library.d.ts:2:5
     2     message2: string;
           ~~~~~~~~
+    'message2' is declared here.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js
index 9d62bab02b1b0..ae50819dd158f 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js
@@ -611,6 +611,7 @@ Output::
 [HH:MM:SS AM] Project 'project3.tsconfig.json' is up to date because newest input 'other2.ts' is older than output 'project3.tsconfig.tsbuildinfo'
 
 error TS5083: Cannot read file '/user/username/projects/project/extendsConfig2.tsconfig.json'.
+
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/reexport/Reports-errors-correctly.js b/tsc/testdata/baselines/reference/tsbuildWatch/reexport/Reports-errors-correctly.js
index e763e740bf64d..5fd9f7e1a78bd 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/reexport/Reports-errors-correctly.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/reexport/Reports-errors-correctly.js
@@ -249,9 +249,10 @@ Output::
 3 export const session: Session = {
                ~~~~~~~
 
-  out/pure/session.d.ts:3:5 - 'bar' is declared here.
+  out/pure/session.d.ts:3:5
     3     bar: number;
           ~~~
+    'bar' is declared here.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors-when-test-does-not-reference-core.js b/tsc/testdata/baselines/reference/tsbuildWatch/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors-when-test-does-not-reference-core.js
index e428153fc5354..3f5f319baf05e 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors-when-test-does-not-reference-core.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors-when-test-does-not-reference-core.js
@@ -78,9 +78,10 @@ Output::
 3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                                                   ~~~~~~~~
 
-  core/index.ts:3:26 - An argument for 'a' was not provided.
+  core/index.ts:3:26
     3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                ~~~~~~~~~
+    An argument for 'a' was not provided.
 
 [HH:MM:SS AM] Project 'logic/tsconfig.json' can't be built because its dependency 'core' has errors
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors.js b/tsc/testdata/baselines/reference/tsbuildWatch/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors.js
index 24ee4890e7ad0..26adb0086f507 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors.js
@@ -79,9 +79,10 @@ Output::
 3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                                                   ~~~~~~~~
 
-  core/index.ts:3:26 - An argument for 'a' was not provided.
+  core/index.ts:3:26
     3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                ~~~~~~~~~
+    An argument for 'a' was not provided.
 
 [HH:MM:SS AM] Project 'logic/tsconfig.json' can't be built because its dependency 'core' has errors
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/sample/watches-config-files-that-are-not-present.js b/tsc/testdata/baselines/reference/tsbuildWatch/sample/watches-config-files-that-are-not-present.js
index f726961eaf767..8ab1914a6e512 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/sample/watches-config-files-that-are-not-present.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/sample/watches-config-files-that-are-not-present.js
@@ -54,6 +54,7 @@ Output::
 [HH:MM:SS AM] Starting compilation in watch mode...
 
 error TS6053: File '/user/username/projects/sample1/logic/tsconfig.json' not found.
+
 tests/tsconfig.json:4:9 - error TS6053: File '/user/username/projects/sample1/logic' not found.
 
 4         { "path": "../logic" },
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-incorrect-compiler-option-value.js b/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-incorrect-compiler-option-value.js
index a5717b385b1ad..e2a0f039d1534 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-incorrect-compiler-option-value.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-incorrect-compiler-option-value.js
@@ -7,3 +7,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS6046: Argument for '--lib' option must be: 'es5', 'es6', 'es2015', 'es7', 'es2016', 'es2017', 'es2018', 'es2019', 'es2020', 'es2021', 'es2022', 'es2023', 'es2024', 'es2025', 'esnext', 'dom', 'dom.iterable', 'dom.asynciterable', 'webworker', 'webworker.importscripts', 'webworker.iterable', 'webworker.asynciterable', 'scripthost', 'es2015.core', 'es2015.collection', 'es2015.generator', 'es2015.iterable', 'es2015.promise', 'es2015.proxy', 'es2015.reflect', 'es2015.symbol', 'es2015.symbol.wellknown', 'es2016.array.include', 'es2016.intl', 'es2017.arraybuffer', 'es2017.date', 'es2017.object', 'es2017.sharedmemory', 'es2017.string', 'es2017.intl', 'es2017.typedarrays', 'es2018.asyncgenerator', 'es2018.asynciterable', 'es2018.intl', 'es2018.promise', 'es2018.regexp', 'es2019.array', 'es2019.object', 'es2019.string', 'es2019.symbol', 'es2019.intl', 'es2020.bigint', 'es2020.date', 'es2020.promise', 'es2020.sharedmemory', 'es2020.string', 'es2020.symbol.wellknown', 'es2020.intl', 'es2020.number', 'es2021.promise', 'es2021.string', 'es2021.weakref', 'es2021.intl', 'es2022.array', 'es2022.error', 'es2022.intl', 'es2022.object', 'es2022.string', 'es2022.regexp', 'es2023.array', 'es2023.collection', 'es2023.intl', 'es2024.arraybuffer', 'es2024.collection', 'es2024.object', 'es2024.promise', 'es2024.regexp', 'es2024.sharedmemory', 'es2024.string', 'es2025.collection', 'es2025.float16', 'es2025.intl', 'es2025.iterator', 'es2025.promise', 'es2025.regexp', 'esnext.asynciterable', 'esnext.symbol', 'esnext.bigint', 'esnext.weakref', 'esnext.object', 'esnext.regexp', 'esnext.string', 'esnext.float16', 'esnext.iterator', 'esnext.promise', 'esnext.array', 'esnext.collection', 'esnext.date', 'esnext.decorators', 'esnext.disposable', 'esnext.error', 'esnext.intl', 'esnext.sharedmemory', 'esnext.temporal', 'esnext.typedarrays', 'decorators', 'decorators.legacy'.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-incorrect-compiler-option.js b/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-incorrect-compiler-option.js
index c31779e874f48..ab4cf00b46ddc 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-incorrect-compiler-option.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-incorrect-compiler-option.js
@@ -7,3 +7,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5023: Unknown compiler option '--someNonExistOption'.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-tsconfig.json.js b/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-tsconfig.json.js
index 543a4d4988002..c422ba28acf9a 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-tsconfig.json.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-tsconfig.json.js
@@ -16,3 +16,4 @@ ExitStatus:: Success
 Output::
 error TS5054: A 'tsconfig.json' file is already defined at: '/home/src/workspaces/project/tsconfig.json'.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/Parse-enum-type-options.js b/tsc/testdata/baselines/reference/tsc/commandLine/Parse-enum-type-options.js
index b717b2f59c748..4de743b46dda3 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/Parse-enum-type-options.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/Parse-enum-type-options.js
@@ -9,6 +9,7 @@ Output::
   The file is in the program because:
     Root file specified for compilation
 
+
 Found 1 error.
 
 //// [/home/src/tslibs/TS/Lib/lib.esnext.full.d.ts] *Lib*
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/bad-locale.js b/tsc/testdata/baselines/reference/tsc/commandLine/bad-locale.js
index 5d1ad434cd988..1444c0edb4086 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/bad-locale.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/bad-locale.js
@@ -7,3 +7,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS6048: Locale must be an IETF BCP 47 language tag. Examples: 'en', 'ja-jp'.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-extended-tsconfig-in-different-folder-does-not-exist.js b/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-extended-tsconfig-in-different-folder-does-not-exist.js
index 117c61bb6b919..dca7ad9a8bbcc 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-extended-tsconfig-in-different-folder-does-not-exist.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-extended-tsconfig-in-different-folder-does-not-exist.js
@@ -19,6 +19,7 @@ Output::
   The file is in the program because:
     Part of 'files' list in tsconfig.json
 
+
 Found 1 error.
 
 //// [/home/src/tslibs/TS/Lib/lib.es2025.full.d.ts] *Lib*
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-tsconfig-does-not-exist.js b/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-tsconfig-does-not-exist.js
index df87dd1cf194d..9700068259c1f 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-tsconfig-does-not-exist.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-tsconfig-does-not-exist.js
@@ -12,9 +12,11 @@ Output::
 error TS6231: Could not resolve the path '/home/src/workspaces/project/src/doesNotExist' with the extensions: '.ts', '.tsx', '.d.ts', '.cts', '.d.cts', '.mts', '.d.mts'.
   The file is in the program because:
     Part of 'files' list in tsconfig.json
-  tsconfig.json:2:31 - File is matched by 'files' list specified here.
+
+  tsconfig.json:2:31
     2                     "files": ["./src/doesNotExist"]
                                     ~~~~~~~~~~~~~~~~~~~~
+    File is matched by 'files' list specified here.
 
 
 Found 1 error.
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-tsconfig-exists.js b/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-tsconfig-exists.js
index 1bb69d8e84d93..4137c78adecd9 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-tsconfig-exists.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-tsconfig-exists.js
@@ -14,9 +14,11 @@ Output::
 error TS6231: Could not resolve the path '/home/src/workspaces/project/src/script' with the extensions: '.ts', '.tsx', '.d.ts', '.cts', '.d.cts', '.mts', '.d.mts'.
   The file is in the program because:
     Part of 'files' list in tsconfig.json
-  tsconfig.json:2:31 - File is matched by 'files' list specified here.
+
+  tsconfig.json:2:31
     2                     "files": ["./src/script"]
                                     ~~~~~~~~~~~~~~
+    File is matched by 'files' list specified here.
 
 
 Found 1 error.
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-on-command-line-exists.js b/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-on-command-line-exists.js
index 7689ac253590b..ae0eb00de4fc0 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-on-command-line-exists.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-on-command-line-exists.js
@@ -11,6 +11,7 @@ Output::
   The file is in the program because:
     Root file specified for compilation
 
+
 Found 1 error.
 
 //// [/home/src/tslibs/TS/Lib/lib.es2025.full.d.ts] *Lib*
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/file-in-tsconfig-does-not-exist.js b/tsc/testdata/baselines/reference/tsc/commandLine/file-in-tsconfig-does-not-exist.js
index c80648cdf5fc0..0ae1d15323df1 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/file-in-tsconfig-does-not-exist.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/file-in-tsconfig-does-not-exist.js
@@ -12,9 +12,11 @@ Output::
 error TS6053: File '/home/src/workspaces/project/src/doesNotExist.ts' not found.
   The file is in the program because:
     Part of 'files' list in tsconfig.json
-  tsconfig.json:2:31 - File is matched by 'files' list specified here.
+
+  tsconfig.json:2:31
     2                     "files": ["./src/doesNotExist.ts"]
                                     ~~~~~~~~~~~~~~~~~~~~~~~
+    File is matched by 'files' list specified here.
 
 
 Found 1 error.
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/non-object-config-root.js b/tsc/testdata/baselines/reference/tsc/commandLine/non-object-config-root.js
index c6d3698f57e9c..47c0e30593c69 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/non-object-config-root.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/non-object-config-root.js
@@ -8,6 +8,7 @@ tsgo
 ExitStatus:: DiagnosticsPresent_OutputsGenerated
 Output::
 error TS18003: No inputs were found in config file '/home/src/workspaces/project/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
+
 tsconfig.json:1:1 - error TS5092: The root value of a 'tsconfig.json' file must be an object.
 
 1 []
diff --git a/tsc/testdata/baselines/reference/tsc/contentMapperFailures/initialization-failure-reports-one-project-error.js b/tsc/testdata/baselines/reference/tsc/contentMapperFailures/initialization-failure-reports-one-project-error.js
index 71ba40313f864..22c0e3d09a871 100644
--- a/tsc/testdata/baselines/reference/tsc/contentMapperFailures/initialization-failure-reports-one-project-error.js
+++ b/tsc/testdata/baselines/reference/tsc/contentMapperFailures/initialization-failure-reports-one-project-error.js
@@ -39,6 +39,7 @@ Output::
 error TS100057: The content mapper 'missing' could not be initialized.
   The content mapper command 'missing-mapper' could not be started: contentmappertest: unknown mapper command [missing-mapper]
 
+
 Found 1 error.
 
 //// [/home/src/tslibs/TS/Lib/lib.es2025.full.d.ts] *Lib*
diff --git a/tsc/testdata/baselines/reference/tsc/contentMapperFailures/mapper-is-disabled-after-repeated-failures.js b/tsc/testdata/baselines/reference/tsc/contentMapperFailures/mapper-is-disabled-after-repeated-failures.js
index 9aed4ac03b683..ece8f82a664d3 100644
--- a/tsc/testdata/baselines/reference/tsc/contentMapperFailures/mapper-is-disabled-after-repeated-failures.js
+++ b/tsc/testdata/baselines/reference/tsc/contentMapperFailures/mapper-is-disabled-after-repeated-failures.js
@@ -40,6 +40,7 @@ tsgo --runExternalCode --singleThreaded
 ExitStatus:: DiagnosticsPresent_OutputsGenerated
 Output::
 error TS100026: The content mapper 'fail' failed 5 times and will not be used.
+
 c.vue:1:1 - error TS100025: The content mapper 'fail' failed to transform this file.
   The content mapper process failed while handling the transform request.
 
diff --git a/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/two-files-exist-on-disk-that-differs-only-in-casing.js b/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/two-files-exist-on-disk-that-differs-only-in-casing.js
index f726afec245e9..c648ddc9ff1d2 100644
--- a/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/two-files-exist-on-disk-that-differs-only-in-casing.js
+++ b/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/two-files-exist-on-disk-that-differs-only-in-casing.js
@@ -23,9 +23,10 @@ Output::
 1 import {x} from "./D"
                   ~~~~~
 
-  tsconfig.json:2:23 - File is matched by 'files' list specified here.
+  tsconfig.json:2:23
     2     "files": ["c.ts", "d.ts"]
                             ~~~~~~
+    File is matched by 'files' list specified here.
 
 
 Found 1 error in c.ts:1
diff --git a/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/when-file-is-included-from-multiple-places-with-different-casing.js b/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/when-file-is-included-from-multiple-places-with-different-casing.js
index 5c31260cf9c03..254c084931dda 100644
--- a/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/when-file-is-included-from-multiple-places-with-different-casing.js
+++ b/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/when-file-is-included-from-multiple-places-with-different-casing.js
@@ -36,25 +36,26 @@ Output::
 2 import * as xs2 from "fp-ts/lib/struct";
                        ~~~~~~~~~~~~~~~~~~
 
-  src/anotherFile.ts:1:22 - File is included via import here.
+  src/anotherFile.ts:1:22
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
-
-  src/anotherFile.ts:2:22 - File is included via import here.
+    File is included via import here.
+  src/anotherFile.ts:2:22
     2 import * as xs2 from "fp-ts/lib/struct";
                            ~~~~~~~~~~~~~~~~~~
-
-  src/Struct.d.ts:1:22 - File is included via import here.
+    File is included via import here.
+  src/Struct.d.ts:1:22
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
-
-  src/oneMore.ts:1:22 - File is included via import here.
+    File is included via import here.
+  src/oneMore.ts:1:22
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
-
-  src/oneMore.ts:2:22 - File is included via import here.
+    File is included via import here.
+  src/oneMore.ts:2:22
     2 import * as xs2 from "fp-ts/lib/struct";
                            ~~~~~~~~~~~~~~~~~~
+    File is included via import here.
 
 src/Struct.d.ts:4:22 - error TS1149: File name '/home/src/projects/project/src/struct.d.ts' differs from already included file name '/home/src/projects/project/src/Struct.d.ts' only in casing.
   The file is in the program because:
@@ -69,25 +70,26 @@ Output::
 4 import * as xs4 from "./struct";
                        ~~~~~~~~~~
 
-  src/anotherFile.ts:3:22 - File is included via import here.
+  src/anotherFile.ts:3:22
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-
-  src/Struct.d.ts:3:22 - File is included via import here.
+    File is included via import here.
+  src/Struct.d.ts:3:22
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-
-  src/anotherFile.ts:4:22 - File is included via import here.
+    File is included via import here.
+  src/anotherFile.ts:4:22
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
-
-  src/oneMore.ts:3:22 - File is included via import here.
+    File is included via import here.
+  src/oneMore.ts:3:22
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-
-  src/oneMore.ts:4:22 - File is included via import here.
+    File is included via import here.
+  src/oneMore.ts:4:22
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
+    File is included via import here.
 
 src/anotherFile.ts:2:22 - error TS1149: File name '/home/src/projects/project/node_modules/fp-ts/lib/struct.d.ts' differs from already included file name '/home/src/projects/project/node_modules/fp-ts/lib/Struct.d.ts' only in casing.
   The file is in the program because:
@@ -101,25 +103,26 @@ Output::
 2 import * as xs2 from "fp-ts/lib/struct";
                        ~~~~~~~~~~~~~~~~~~
 
-  src/anotherFile.ts:1:22 - File is included via import here.
+  src/anotherFile.ts:1:22
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
-
-  src/Struct.d.ts:1:22 - File is included via import here.
+    File is included via import here.
+  src/Struct.d.ts:1:22
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
-
-  src/Struct.d.ts:2:22 - File is included via import here.
+    File is included via import here.
+  src/Struct.d.ts:2:22
     2 import * as xs2 from "fp-ts/lib/struct";
                            ~~~~~~~~~~~~~~~~~~
-
-  src/oneMore.ts:1:22 - File is included via import here.
+    File is included via import here.
+  src/oneMore.ts:1:22
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
-
-  src/oneMore.ts:2:22 - File is included via import here.
+    File is included via import here.
+  src/oneMore.ts:2:22
     2 import * as xs2 from "fp-ts/lib/struct";
                            ~~~~~~~~~~~~~~~~~~
+    File is included via import here.
 
 src/anotherFile.ts:3:22 - error TS1261: Already included file name '/home/src/projects/project/src/Struct.d.ts' differs from file name '/home/src/projects/project/src/struct.d.ts' only in casing.
   The file is in the program because:
@@ -134,25 +137,26 @@ Output::
 3 import * as xs3 from "./Struct";
                        ~~~~~~~~~~
 
-  src/Struct.d.ts:3:22 - File is included via import here.
+  src/Struct.d.ts:3:22
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-
-  src/Struct.d.ts:4:22 - File is included via import here.
+    File is included via import here.
+  src/Struct.d.ts:4:22
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
-
-  src/anotherFile.ts:4:22 - File is included via import here.
+    File is included via import here.
+  src/anotherFile.ts:4:22
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
-
-  src/oneMore.ts:3:22 - File is included via import here.
+    File is included via import here.
+  src/oneMore.ts:3:22
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-
-  src/oneMore.ts:4:22 - File is included via import here.
+    File is included via import here.
+  src/oneMore.ts:4:22
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
+    File is included via import here.
 
 src/anotherFile.ts:4:22 - error TS1149: File name '/home/src/projects/project/src/struct.d.ts' differs from already included file name '/home/src/projects/project/src/Struct.d.ts' only in casing.
   The file is in the program because:
@@ -167,25 +171,26 @@ Output::
 4 import * as xs4 from "./struct";
                        ~~~~~~~~~~
 
-  src/anotherFile.ts:3:22 - File is included via import here.
+  src/anotherFile.ts:3:22
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-
-  src/Struct.d.ts:3:22 - File is included via import here.
+    File is included via import here.
+  src/Struct.d.ts:3:22
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-
-  src/Struct.d.ts:4:22 - File is included via import here.
+    File is included via import here.
+  src/Struct.d.ts:4:22
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
-
-  src/oneMore.ts:3:22 - File is included via import here.
+    File is included via import here.
+  src/oneMore.ts:3:22
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-
-  src/oneMore.ts:4:22 - File is included via import here.
+    File is included via import here.
+  src/oneMore.ts:4:22
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
+    File is included via import here.
 
 src/oneMore.ts:2:22 - error TS1149: File name '/home/src/projects/project/node_modules/fp-ts/lib/struct.d.ts' differs from already included file name '/home/src/projects/project/node_modules/fp-ts/lib/Struct.d.ts' only in casing.
   The file is in the program because:
@@ -199,25 +204,26 @@ Output::
 2 import * as xs2 from "fp-ts/lib/struct";
                        ~~~~~~~~~~~~~~~~~~
 
-  src/anotherFile.ts:1:22 - File is included via import here.
+  src/anotherFile.ts:1:22
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
-
-  src/anotherFile.ts:2:22 - File is included via import here.
+    File is included via import here.
+  src/anotherFile.ts:2:22
     2 import * as xs2 from "fp-ts/lib/struct";
                            ~~~~~~~~~~~~~~~~~~
-
-  src/Struct.d.ts:1:22 - File is included via import here.
+    File is included via import here.
+  src/Struct.d.ts:1:22
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
-
-  src/Struct.d.ts:2:22 - File is included via import here.
+    File is included via import here.
+  src/Struct.d.ts:2:22
     2 import * as xs2 from "fp-ts/lib/struct";
                            ~~~~~~~~~~~~~~~~~~
-
-  src/oneMore.ts:1:22 - File is included via import here.
+    File is included via import here.
+  src/oneMore.ts:1:22
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
+    File is included via import here.
 
 src/oneMore.ts:4:22 - error TS1149: File name '/home/src/projects/project/src/struct.d.ts' differs from already included file name '/home/src/projects/project/src/Struct.d.ts' only in casing.
   The file is in the program because:
@@ -232,25 +238,26 @@ Output::
 4 import * as xs4 from "./struct";
                        ~~~~~~~~~~
 
-  src/anotherFile.ts:3:22 - File is included via import here.
+  src/anotherFile.ts:3:22
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-
-  src/Struct.d.ts:3:22 - File is included via import here.
+    File is included via import here.
+  src/Struct.d.ts:3:22
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-
-  src/Struct.d.ts:4:22 - File is included via import here.
+    File is included via import here.
+  src/Struct.d.ts:4:22
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
-
-  src/anotherFile.ts:4:22 - File is included via import here.
+    File is included via import here.
+  src/anotherFile.ts:4:22
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
-
-  src/oneMore.ts:3:22 - File is included via import here.
+    File is included via import here.
+  src/oneMore.ts:3:22
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
+    File is included via import here.
 
 ../../tslibs/TS/Lib/lib.es2025.full.d.ts
    Default library for target 'ES2025'
diff --git a/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/with-relative-and-non-relative-file-resolutions.js b/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/with-relative-and-non-relative-file-resolutions.js
index cb332937d4fa1..f4808d4d1fdc1 100644
--- a/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/with-relative-and-non-relative-file-resolutions.js
+++ b/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/with-relative-and-non-relative-file-resolutions.js
@@ -20,9 +20,10 @@ Output::
 2 import * as xs2 from "fp-ts/lib/struct";
                        ~~~~~~~~~~~~~~~~~~
 
-  src/struct.d.ts:1:22 - File is included via import here.
+  src/struct.d.ts:1:22
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
+    File is included via import here.
 
 src/struct.d.ts:3:22 - error TS1149: File name '/user/username/projects/myproject/src/Struct.d.ts' differs from already included file name '/user/username/projects/myproject/src/struct.d.ts' only in casing.
   The file is in the program because:
@@ -33,9 +34,10 @@ Output::
 3 import * as xs3 from "./Struct";
                        ~~~~~~~~~~
 
-  src/struct.d.ts:4:22 - File is included via import here.
+  src/struct.d.ts:4:22
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
+    File is included via import here.
 
 ../../../../home/src/tslibs/TS/Lib/lib.es2025.full.d.ts
    Default library for target 'ES2025'
diff --git a/tsc/testdata/baselines/reference/tsc/generateTrace/generateTrace-with-multiple-files-and-complex-types.js b/tsc/testdata/baselines/reference/tsc/generateTrace/generateTrace-with-multiple-files-and-complex-types.js
index befa8be5368c2..b2f228804fd92 100644
--- a/tsc/testdata/baselines/reference/tsc/generateTrace/generateTrace-with-multiple-files-and-complex-types.js
+++ b/tsc/testdata/baselines/reference/tsc/generateTrace/generateTrace-with-multiple-files-and-complex-types.js
@@ -31,9 +31,10 @@ Output::
 2 const c: Container<number> = { value: 42, map: (fn) => ({ value: fn(42), map: c.map }) };
                                                                            ~~~
 
-  types.ts:3:5 - The expected type comes from property 'map' which is declared here on type 'Container<U>'
+  types.ts:3:5
     3     map<U>(fn: (x: T) => U): Container<U>;
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+    The expected type comes from property 'map' which is declared here on type 'Container<U>'
 
 
 Found 1 error in main.ts:2
diff --git a/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-when-config-file-absent-with---ignoreConfig.js b/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-when-config-file-absent-with---ignoreConfig.js
index 74d6e078632f8..36d1767af4c7d 100644
--- a/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-when-config-file-absent-with---ignoreConfig.js
+++ b/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-when-config-file-absent-with---ignoreConfig.js
@@ -13,3 +13,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5042: Option 'project' cannot be mixed with source files on a command line.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-when-config-file-absent.js b/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-when-config-file-absent.js
index c557a4537a6d2..de5d158171559 100644
--- a/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-when-config-file-absent.js
+++ b/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-when-config-file-absent.js
@@ -13,3 +13,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5042: Option 'project' cannot be mixed with source files on a command line.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-with---ignoreConfig.js b/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-with---ignoreConfig.js
index f325237920c83..e8f3de2c08556 100644
--- a/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-with---ignoreConfig.js
+++ b/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-with---ignoreConfig.js
@@ -17,3 +17,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5042: Option 'project' cannot be mixed with source files on a command line.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files.js b/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files.js
index 35141cbcc6df7..38658f4416efa 100644
--- a/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files.js
+++ b/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files.js
@@ -17,3 +17,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5042: Option 'project' cannot be mixed with source files on a command line.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-files.js b/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-files.js
index fab3875627728..823191d8e5859 100644
--- a/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-files.js
+++ b/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-files.js
@@ -17,3 +17,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5112: tsconfig.json is present but will not be loaded if files are specified on commandline. Use '--ignoreConfig' to skip this error.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-project-when-config-file-absent-with---ignoreConfig.js b/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-project-when-config-file-absent-with---ignoreConfig.js
index ed09be7914a74..5c8058ed0117a 100644
--- a/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-project-when-config-file-absent-with---ignoreConfig.js
+++ b/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-project-when-config-file-absent-with---ignoreConfig.js
@@ -13,3 +13,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5081: Cannot find a tsconfig.json file at the current directory: /home/src/workspaces/project/tsconfig.json.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-project-when-config-file-absent.js b/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-project-when-config-file-absent.js
index c8d7560ae5573..4a2bdf2b1c817 100644
--- a/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-project-when-config-file-absent.js
+++ b/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-project-when-config-file-absent.js
@@ -13,3 +13,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5081: Cannot find a tsconfig.json file at the current directory: /home/src/workspaces/project/tsconfig.json.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/incremental/Compile-incremental-with-case-insensitive-file-names.js b/tsc/testdata/baselines/reference/tsc/incremental/Compile-incremental-with-case-insensitive-file-names.js
index 3d384abf36137..922fd45f1e736 100644
--- a/tsc/testdata/baselines/reference/tsc/incremental/Compile-incremental-with-case-insensitive-file-names.js
+++ b/tsc/testdata/baselines/reference/tsc/incremental/Compile-incremental-with-case-insensitive-file-names.js
@@ -52,9 +52,10 @@ Output::
 1 import type { Foo } from 'somelib';
                            ~~~~~~~~~
 
-  ../node_modules/lib1/index.d.ts:1:26 - File is included via import here.
+  ../node_modules/lib1/index.d.ts:1:26
     1 import type { Foo } from 'someLib';
                                ~~~~~~~~~
+    File is included via import here.
 
 
 Found 1 error in ../node_modules/lib2/index.d.ts:1
diff --git a/tsc/testdata/baselines/reference/tsc/incremental/change-to-modifier-of-class-expression-field-with-declaration-emit-enabled.js b/tsc/testdata/baselines/reference/tsc/incremental/change-to-modifier-of-class-expression-field-with-declaration-emit-enabled.js
index 4a7e96ec311d9..8577ec9763930 100644
--- a/tsc/testdata/baselines/reference/tsc/incremental/change-to-modifier-of-class-expression-field-with-declaration-emit-enabled.js
+++ b/tsc/testdata/baselines/reference/tsc/incremental/change-to-modifier-of-class-expression-field-with-declaration-emit-enabled.js
@@ -269,9 +269,10 @@ Output::
 6 const wrapper = () => Messageable();
         ~~~~~~~
 
-  MessageablePerson.ts:6:7 - Add a type annotation to the variable wrapper.
+  MessageablePerson.ts:6:7
     6 const wrapper = () => Messageable();
             ~~~~~~~
+    Add a type annotation to the variable wrapper.
 
 MessageablePerson.ts:7:26 - error TS2304: Cannot find name 'InstanceType'.
 
@@ -439,9 +440,10 @@ Output::
 6 const wrapper = () => Messageable();
         ~~~~~~~
 
-  MessageablePerson.ts:6:7 - Add a type annotation to the variable wrapper.
+  MessageablePerson.ts:6:7
     6 const wrapper = () => Messageable();
             ~~~~~~~
+    Add a type annotation to the variable wrapper.
 
 MessageablePerson.ts:7:26 - error TS2304: Cannot find name 'InstanceType'.
 
diff --git a/tsc/testdata/baselines/reference/tsc/incremental/internal-symbolname-in-tsbuildInfo.js b/tsc/testdata/baselines/reference/tsc/incremental/internal-symbolname-in-tsbuildInfo.js
index e33fcabf4b84f..9ca161633691c 100644
--- a/tsc/testdata/baselines/reference/tsc/incremental/internal-symbolname-in-tsbuildInfo.js
+++ b/tsc/testdata/baselines/reference/tsc/incremental/internal-symbolname-in-tsbuildInfo.js
@@ -100,9 +100,10 @@ Output::
 3     length: files.length,
       ~~~~~~~~~~~~~~~~~~~~
 
-  a.ts:8:5 - This spread always overwrites this property.
+  a.ts:8:5
     8     ...files,
           ~~~~~~~~
+    This spread always overwrites this property.
 
 a.ts:5:5 - error TS2783: '�@iterator@<symbolId>' is specified more than once, so this usage will be overwritten.
 
@@ -113,9 +114,10 @@ Output::
 7     },
   ~~~~~
 
-  a.ts:8:5 - This spread always overwrites this property.
+  a.ts:8:5
     8     ...files,
           ~~~~~~~~
+    This spread always overwrites this property.
 
 
 Found 2 errors in the same file, starting at: a.ts:3
@@ -143,9 +145,10 @@ Output::
 3     length: files.length,
       ~~~~~~~~~~~~~~~~~~~~
 
-  a.ts:8:5 - This spread always overwrites this property.
+  a.ts:8:5
     8     ...files,
           ~~~~~~~~
+    This spread always overwrites this property.
 
 a.ts:5:5 - error TS2783: '�@iterator@<symbolId>' is specified more than once, so this usage will be overwritten.
 
@@ -156,9 +159,10 @@ Output::
 7     },
   ~~~~~
 
-  a.ts:8:5 - This spread always overwrites this property.
+  a.ts:8:5
     8     ...files,
           ~~~~~~~~
+    This spread always overwrites this property.
 
 
 Found 2 errors in the same file, starting at: a.ts:3
@@ -177,9 +181,10 @@ Output::
 3     length: files.length,
       ~~~~~~~~~~~~~~~~~~~~
 
-  a.ts:8:5 - This spread always overwrites this property.
+  a.ts:8:5
     8     ...files,
           ~~~~~~~~
+    This spread always overwrites this property.
 
 a.ts:5:5 - error TS2783: '�@iterator@<symbolId>' is specified more than once, so this usage will be overwritten.
 
@@ -190,9 +195,10 @@ Output::
 7     },
   ~~~~~
 
-  a.ts:8:5 - This spread always overwrites this property.
+  a.ts:8:5
     8     ...files,
           ~~~~~~~~
+    This spread always overwrites this property.
 
 
 Found 2 errors in the same file, starting at: a.ts:3
@@ -325,9 +331,10 @@ Output::
 3     length: files.length,
       ~~~~~~~~~~~~~~~~~~~~
 
-  a.ts:8:5 - This spread always overwrites this property.
+  a.ts:8:5
     8     ...files,
           ~~~~~~~~
+    This spread always overwrites this property.
 
 a.ts:5:5 - error TS2783: '�@iterator@<symbolId>' is specified more than once, so this usage will be overwritten.
 
@@ -338,9 +345,10 @@ Output::
 7     },
   ~~~~~
 
-  a.ts:8:5 - This spread always overwrites this property.
+  a.ts:8:5
     8     ...files,
           ~~~~~~~~
+    This spread always overwrites this property.
 
 
 Found 2 errors in the same file, starting at: a.ts:3
diff --git a/tsc/testdata/baselines/reference/tsc/incremental/js-file-with-import-in-jsdoc-in-composite-project.js b/tsc/testdata/baselines/reference/tsc/incremental/js-file-with-import-in-jsdoc-in-composite-project.js
index 2cacb067b1ce2..36dd0315a0246 100644
--- a/tsc/testdata/baselines/reference/tsc/incremental/js-file-with-import-in-jsdoc-in-composite-project.js
+++ b/tsc/testdata/baselines/reference/tsc/incremental/js-file-with-import-in-jsdoc-in-composite-project.js
@@ -32,6 +32,7 @@ ExitStatus:: DiagnosticsPresent_OutputsGenerated
 Output::
 error TS2318: Cannot find global type 'Promise'.
 
+
 Found 1 error.
 
 //// [/home/src/tslibs/TS/Lib/lib.es2025.full.d.ts] *Lib*
diff --git a/tsc/testdata/baselines/reference/tsc/incremental/serializing-error-chain.js b/tsc/testdata/baselines/reference/tsc/incremental/serializing-error-chain.js
index 8d4c59f060791..3ec10629a3531 100644
--- a/tsc/testdata/baselines/reference/tsc/incremental/serializing-error-chain.js
+++ b/tsc/testdata/baselines/reference/tsc/incremental/serializing-error-chain.js
@@ -37,9 +37,10 @@ Output::
 10 (<Component>
      ~~~~~~~~~
 
-  index.tsx:9:18 - The last overload is declared here.
+  index.tsx:9:18
     9 declare function Component(props: { children?: number }): any;
                        ~~~~~~~~~
+    The last overload is declared here.
 
 
 Found 1 error in index.tsx:10
@@ -215,9 +216,10 @@ Output::
 10 (<Component>
      ~~~~~~~~~
 
-  index.tsx:9:18 - The last overload is declared here.
+  index.tsx:9:18
     9 declare function Component(props: { children?: number }): any;
                        ~~~~~~~~~
+    The last overload is declared here.
 
 
 Found 1 error in index.tsx:10
diff --git a/tsc/testdata/baselines/reference/tsc/libraryResolution/when-noLib-toggles.js b/tsc/testdata/baselines/reference/tsc/libraryResolution/when-noLib-toggles.js
index 1b616dd558d32..f431804b71919 100644
--- a/tsc/testdata/baselines/reference/tsc/libraryResolution/when-noLib-toggles.js
+++ b/tsc/testdata/baselines/reference/tsc/libraryResolution/when-noLib-toggles.js
@@ -129,15 +129,25 @@ tsgo --noLib
 ExitStatus:: DiagnosticsPresent_OutputsGenerated
 Output::
 error TS2318: Cannot find global type 'Array'.
+
 error TS2318: Cannot find global type 'Boolean'.
+
 error TS2318: Cannot find global type 'CallableFunction'.
+
 error TS2318: Cannot find global type 'Function'.
+
 error TS2318: Cannot find global type 'IArguments'.
+
 error TS2318: Cannot find global type 'NewableFunction'.
+
 error TS2318: Cannot find global type 'Number'.
+
 error TS2318: Cannot find global type 'Object'.
+
 error TS2318: Cannot find global type 'RegExp'.
+
 error TS2318: Cannot find global type 'String'.
+
 tsconfig.json:5:9 - error TS5053: Option 'lib' cannot be specified with option 'noLib'.
 
 5         "lib": ["es6"],
diff --git a/tsc/testdata/baselines/reference/tsc/noCheck/dts-errors-with-incremental.js b/tsc/testdata/baselines/reference/tsc/noCheck/dts-errors-with-incremental.js
index 1a8b5b0cabf41..1c72c4656f665 100644
--- a/tsc/testdata/baselines/reference/tsc/noCheck/dts-errors-with-incremental.js
+++ b/tsc/testdata/baselines/reference/tsc/noCheck/dts-errors-with-incremental.js
@@ -21,9 +21,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -175,9 +176,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -408,9 +410,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -534,9 +537,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -558,9 +562,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -960,9 +965,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsc/noCheck/dts-errors.js b/tsc/testdata/baselines/reference/tsc/noCheck/dts-errors.js
index 860941f8f918d..023d11545620a 100644
--- a/tsc/testdata/baselines/reference/tsc/noCheck/dts-errors.js
+++ b/tsc/testdata/baselines/reference/tsc/noCheck/dts-errors.js
@@ -21,9 +21,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -75,9 +76,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -166,9 +168,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -193,9 +196,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -216,9 +220,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -297,9 +302,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/changes-composite.js b/tsc/testdata/baselines/reference/tsc/noEmit/changes-composite.js
index f0dbfd1471c69..64fdb8d4fa1c2 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/changes-composite.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/changes-composite.js
@@ -337,18 +337,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -910,18 +912,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1185,18 +1189,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1227,18 +1233,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1269,18 +1277,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1311,18 +1321,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/changes-incremental-declaration.js b/tsc/testdata/baselines/reference/tsc/noEmit/changes-incremental-declaration.js
index 5f3fc47d20272..ecc408c9f6017 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/changes-incremental-declaration.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/changes-incremental-declaration.js
@@ -336,18 +336,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -885,18 +887,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1162,18 +1166,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1204,18 +1210,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1246,18 +1254,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1288,18 +1298,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/changes-incremental.js b/tsc/testdata/baselines/reference/tsc/noEmit/changes-incremental.js
index bb3c5c7a2c2d0..c43702d84746f 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/changes-incremental.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/changes-incremental.js
@@ -278,18 +278,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -803,18 +805,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1053,18 +1057,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1095,18 +1101,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1137,18 +1145,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1179,18 +1189,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-composite.js b/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-composite.js
index ecf00bb71e79e..84c9317bfba8f 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-composite.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-composite.js
@@ -503,18 +503,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-incremental-declaration.js b/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-incremental-declaration.js
index b09fc9259fdb2..941ecb922a353 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-incremental-declaration.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-incremental-declaration.js
@@ -476,18 +476,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-incremental.js b/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-incremental.js
index 138d0771c84bf..2c8d04e9aef50 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-incremental.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-incremental.js
@@ -415,18 +415,20 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5 - 'prop1' is declared here.
+  src/class.ts:2:5
     2     prop1 = 1;
           ~~~~~
+    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-declaration-enable-changes-with-multiple-files.js b/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-declaration-enable-changes-with-multiple-files.js
index 8c767972d02b3..2ff505456cdc3 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-declaration-enable-changes-with-multiple-files.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-declaration-enable-changes-with-multiple-files.js
@@ -162,27 +162,30 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 c.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14 - Add a type annotation to the variable c.
+  c.ts:1:14
     1 export const c = class { private p = 10; };
                    ~
+    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14 - Add a type annotation to the variable d.
+  d.ts:1:14
     1 export const d = class { private p = 10; };
                    ~
+    Add a type annotation to the variable d.
 
 
 Found 3 errors in 3 files.
@@ -394,27 +397,30 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 c.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14 - Add a type annotation to the variable c.
+  c.ts:1:14
     1 export const c = class { private p = 10; };
                    ~
+    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14 - Add a type annotation to the variable d.
+  d.ts:1:14
     1 export const d = class { private p = 10; };
                    ~
+    Add a type annotation to the variable d.
 
 
 Found 3 errors in 3 files.
@@ -638,27 +644,30 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 c.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14 - Add a type annotation to the variable c.
+  c.ts:1:14
     1 export const c = class { private p = 10; };
                    ~
+    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14 - Add a type annotation to the variable d.
+  d.ts:1:14
     1 export const d = class { private p = 10; };
                    ~
+    Add a type annotation to the variable d.
 
 
 Found 3 errors in 3 files.
@@ -1017,18 +1026,20 @@ Output::
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14 - Add a type annotation to the variable c.
+  c.ts:1:14
     1 export const c = class { private p = 10; };
                    ~
+    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14 - Add a type annotation to the variable d.
+  d.ts:1:14
     1 export const d = class { private p = 10; };
                    ~
+    Add a type annotation to the variable d.
 
 
 Found 2 errors in 2 files.
@@ -1222,18 +1233,20 @@ Output::
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14 - Add a type annotation to the variable c.
+  c.ts:1:14
     1 export const c = class { private p = 10; };
                    ~
+    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14 - Add a type annotation to the variable d.
+  d.ts:1:14
     1 export const d = class { private p = 10; };
                    ~
+    Add a type annotation to the variable d.
 
 
 Found 2 errors in 2 files.
@@ -1430,9 +1443,10 @@ Output::
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14 - Add a type annotation to the variable d.
+  d.ts:1:14
     1 export const d = class { private p = 10; };
                    ~
+    Add a type annotation to the variable d.
 
 
 Found 1 error in d.ts:1
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-incremental-as-modules.js b/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-incremental-as-modules.js
index 883fa4cd4945f..d389e09e987eb 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-incremental-as-modules.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-incremental-as-modules.js
@@ -21,9 +21,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -170,9 +171,10 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14 - Add a type annotation to the variable a.
+  a.ts:1:14
     1 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -395,9 +397,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -535,9 +538,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -660,9 +664,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-incremental.js b/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-incremental.js
index 7f8fd52fd1db0..4a41de5c3b6ea 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-incremental.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-incremental.js
@@ -19,9 +19,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -154,9 +155,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -343,9 +345,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -457,9 +460,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -564,9 +568,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors.js b/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors.js
index 299fdcb8dacde..531ebea6d489c 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors.js
@@ -19,9 +19,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -62,9 +63,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -125,9 +127,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -145,9 +148,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -171,9 +175,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsc/noEmitOnError/dts-errors-with-declaration-with-incremental.js b/tsc/testdata/baselines/reference/tsc/noEmitOnError/dts-errors-with-declaration-with-incremental.js
index b1e3920ac2372..a7186d8a190ef 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmitOnError/dts-errors-with-declaration-with-incremental.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmitOnError/dts-errors-with-declaration-with-incremental.js
@@ -29,9 +29,10 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14 - Add a type annotation to the variable a.
+  src/main.ts:2:14
     2 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in src/main.ts:2
@@ -207,9 +208,10 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14 - Add a type annotation to the variable a.
+  src/main.ts:2:14
     2 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in src/main.ts:2
diff --git a/tsc/testdata/baselines/reference/tsc/noEmitOnError/dts-errors-with-declaration.js b/tsc/testdata/baselines/reference/tsc/noEmitOnError/dts-errors-with-declaration.js
index 75a34f056ecbe..7c0b3491e0c37 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmitOnError/dts-errors-with-declaration.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmitOnError/dts-errors-with-declaration.js
@@ -29,9 +29,10 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14 - Add a type annotation to the variable a.
+  src/main.ts:2:14
     2 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in src/main.ts:2
@@ -72,9 +73,10 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14 - Add a type annotation to the variable a.
+  src/main.ts:2:14
     2 export const a = class { private p = 10; };
                    ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in src/main.ts:2
diff --git a/tsc/testdata/baselines/reference/tsc/showConfig/Default-initialized-TSConfig.js b/tsc/testdata/baselines/reference/tsc/showConfig/Default-initialized-TSConfig.js
index b61895595f13b..b25098501b866 100644
--- a/tsc/testdata/baselines/reference/tsc/showConfig/Default-initialized-TSConfig.js
+++ b/tsc/testdata/baselines/reference/tsc/showConfig/Default-initialized-TSConfig.js
@@ -7,3 +7,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5081: Cannot find a tsconfig.json file at the current directory: /home/src/workspaces/project.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-advanced-options.js b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-advanced-options.js
index df5a6782c2511..c9da5e87c69f4 100644
--- a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-advanced-options.js
+++ b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-advanced-options.js
@@ -7,3 +7,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5081: Cannot find a tsconfig.json file at the current directory: /home/src/workspaces/project.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-boolean-value-compiler-options.js b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-boolean-value-compiler-options.js
index da30c08a19cfb..ef73c3042b511 100644
--- a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-boolean-value-compiler-options.js
+++ b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-boolean-value-compiler-options.js
@@ -7,3 +7,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5081: Cannot find a tsconfig.json file at the current directory: /home/src/workspaces/project.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-enum-value-compiler-options.js b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-enum-value-compiler-options.js
index bf3ed802f92a2..0a6957c4d5b27 100644
--- a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-enum-value-compiler-options.js
+++ b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-enum-value-compiler-options.js
@@ -7,3 +7,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5081: Cannot find a tsconfig.json file at the current directory: /home/src/workspaces/project.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-incorrect-compiler-option-value.js b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-incorrect-compiler-option-value.js
index 7902a5f89cdfd..0ae2a3ab700cb 100644
--- a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-incorrect-compiler-option-value.js
+++ b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-incorrect-compiler-option-value.js
@@ -7,3 +7,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS6046: Argument for '--lib' option must be: 'es5', 'es6', 'es2015', 'es7', 'es2016', 'es2017', 'es2018', 'es2019', 'es2020', 'es2021', 'es2022', 'es2023', 'es2024', 'es2025', 'esnext', 'dom', 'dom.iterable', 'dom.asynciterable', 'webworker', 'webworker.importscripts', 'webworker.iterable', 'webworker.asynciterable', 'scripthost', 'es2015.core', 'es2015.collection', 'es2015.generator', 'es2015.iterable', 'es2015.promise', 'es2015.proxy', 'es2015.reflect', 'es2015.symbol', 'es2015.symbol.wellknown', 'es2016.array.include', 'es2016.intl', 'es2017.arraybuffer', 'es2017.date', 'es2017.object', 'es2017.sharedmemory', 'es2017.string', 'es2017.intl', 'es2017.typedarrays', 'es2018.asyncgenerator', 'es2018.asynciterable', 'es2018.intl', 'es2018.promise', 'es2018.regexp', 'es2019.array', 'es2019.object', 'es2019.string', 'es2019.symbol', 'es2019.intl', 'es2020.bigint', 'es2020.date', 'es2020.promise', 'es2020.sharedmemory', 'es2020.string', 'es2020.symbol.wellknown', 'es2020.intl', 'es2020.number', 'es2021.promise', 'es2021.string', 'es2021.weakref', 'es2021.intl', 'es2022.array', 'es2022.error', 'es2022.intl', 'es2022.object', 'es2022.string', 'es2022.regexp', 'es2023.array', 'es2023.collection', 'es2023.intl', 'es2024.arraybuffer', 'es2024.collection', 'es2024.object', 'es2024.promise', 'es2024.regexp', 'es2024.sharedmemory', 'es2024.string', 'es2025.collection', 'es2025.float16', 'es2025.intl', 'es2025.iterator', 'es2025.promise', 'es2025.regexp', 'esnext.asynciterable', 'esnext.symbol', 'esnext.bigint', 'esnext.weakref', 'esnext.object', 'esnext.regexp', 'esnext.string', 'esnext.float16', 'esnext.iterator', 'esnext.promise', 'esnext.array', 'esnext.collection', 'esnext.date', 'esnext.decorators', 'esnext.disposable', 'esnext.error', 'esnext.intl', 'esnext.sharedmemory', 'esnext.temporal', 'esnext.typedarrays', 'decorators', 'decorators.legacy'.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-incorrect-compiler-option.js b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-incorrect-compiler-option.js
index d922215b52019..a01eddac525c2 100644
--- a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-incorrect-compiler-option.js
+++ b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-incorrect-compiler-option.js
@@ -7,3 +7,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5023: Unknown compiler option '--someNonExistOption'.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-list-compiler-options-with-enum-value.js b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-list-compiler-options-with-enum-value.js
index 2677c20cc1436..9a2c1c938b110 100644
--- a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-list-compiler-options-with-enum-value.js
+++ b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-list-compiler-options-with-enum-value.js
@@ -7,3 +7,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5081: Cannot find a tsconfig.json file at the current directory: /home/src/workspaces/project.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-list-compiler-options.js b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-list-compiler-options.js
index 82fb9636f8fba..7ecf617395dca 100644
--- a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-list-compiler-options.js
+++ b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-list-compiler-options.js
@@ -7,3 +7,4 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5081: Cannot find a tsconfig.json file at the current directory: /home/src/workspaces/project.
 
+
diff --git a/tsc/testdata/baselines/reference/tsc/typeAcquisition/parse-tsconfig-with-typeAcquisition.js b/tsc/testdata/baselines/reference/tsc/typeAcquisition/parse-tsconfig-with-typeAcquisition.js
index 5c89ebdf9aa8d..274d196898080 100644
--- a/tsc/testdata/baselines/reference/tsc/typeAcquisition/parse-tsconfig-with-typeAcquisition.js
+++ b/tsc/testdata/baselines/reference/tsc/typeAcquisition/parse-tsconfig-with-typeAcquisition.js
@@ -20,6 +20,7 @@ ExitStatus:: DiagnosticsPresent_OutputsGenerated
 Output::
 error TS18003: No inputs were found in config file '/home/src/workspaces/project/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
 
+
 Found 1 error.
 
 //// [/home/src/workspaces/project/tsconfig.tsbuildinfo] *new* 
diff --git a/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-detects-nested-subdirectory-removed-and-recreated.js b/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-detects-nested-subdirectory-removed-and-recreated.js
index 4cdb0864eaa82..9939bf70ffaee 100644
--- a/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-detects-nested-subdirectory-removed-and-recreated.js
+++ b/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-detects-nested-subdirectory-removed-and-recreated.js
@@ -77,9 +77,10 @@ Signatures::
 Diff:: incremental has prior state and does not report no-inputs error
 --- nonIncremental.output.txt
 +++ incremental.output.txt
-@@ -1,4 +0,0 @@
+@@ -1,5 +0,0 @@
 -error TS18003: No inputs were found in config file '/home/src/workspaces/project/tsconfig.json'. Specified 'include' paths were '["src/**/*.ts"]' and 'exclude' paths were '[]'.
 -
+-
 -Found 1 error.
 -
 
diff --git a/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-handles-tsconfig-deleted.js b/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-handles-tsconfig-deleted.js
index 7c3ab632e031c..18d8af2db3364 100644
--- a/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-handles-tsconfig-deleted.js
+++ b/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-handles-tsconfig-deleted.js
@@ -58,6 +58,7 @@ Edit [0]:: delete tsconfig
 
 Output::
 error TS5083: Cannot read file '/home/src/workspaces/project/tsconfig.json'.
+
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
 
@@ -70,7 +71,7 @@ Directory watches::
 Diff:: incremental reports config read error while clean build without tsconfig prints usage help
 --- nonIncremental.output.txt
 +++ incremental.output.txt
-@@ -1,144 +1,1 @@
+@@ -1,144 +1,2 @@
 -Version FakeTSVersion
 -tsc: The TypeScript Compiler - Version FakeTSVersion
 -
@@ -214,5 +215,4 @@ Diff:: incremental reports config read error while clean build without tsconfig
 -default: true
 -
 -You can learn about all of the compiler options at https://aka.ms/tsc
--
-+error TS5083: Cannot read file '/home/src/workspaces/project/tsconfig.json'.
\ No newline at end of file
++error TS5083: Cannot read file '/home/src/workspaces/project/tsconfig.json'.
diff --git a/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-with-tsconfig-files-list-entry-deleted.js b/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-with-tsconfig-files-list-entry-deleted.js
index 1b0917365955e..e48f05f7a5c8c 100644
--- a/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-with-tsconfig-files-list-entry-deleted.js
+++ b/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-with-tsconfig-files-list-entry-deleted.js
@@ -70,9 +70,11 @@ Output::
 error TS6053: File '/home/src/workspaces/project/b.ts' not found.
   The file is in the program because:
     Part of 'files' list in tsconfig.json
-  tsconfig.json:3:20 - File is matched by 'files' list specified here.
+
+  tsconfig.json:3:20
     3  "files": ["a.ts", "b.ts"]
                          ~~~~~~
+    File is matched by 'files' list specified here.
 
 
 Found 1 error.
diff --git a/tsc/testdata/baselines/reference/tscWatch/noEmit/dts-errors.js b/tsc/testdata/baselines/reference/tscWatch/noEmit/dts-errors.js
index c0a2db979bfec..569570c44d951 100644
--- a/tsc/testdata/baselines/reference/tscWatch/noEmit/dts-errors.js
+++ b/tsc/testdata/baselines/reference/tscWatch/noEmit/dts-errors.js
@@ -21,9 +21,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -157,9 +158,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -196,9 +198,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -239,9 +242,10 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7 - Add a type annotation to the variable a.
+  a.ts:1:7
     1 const a = class { private p = 10; };
             ~
+    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/submoduleAccepted.txt b/tsc/testdata/submoduleAccepted.txt
index b2c6f97649d0a..34729fd0ffea5 100644
--- a/tsc/testdata/submoduleAccepted.txt
+++ b/tsc/testdata/submoduleAccepted.txt
@@ -671,10 +671,7 @@ conformance/circular1.errors.txt.diff
 conformance/circular3.errors.txt.diff
 
 ## Related spans in various errors changed (these baselines are all --pretty)
-compiler/deeplyNestedAssignabilityIssue.errors.txt.diff
-compiler/esModuleInteropPrettyErrorRelatedInformation.errors.txt.diff
 compiler/prettyContextNotDebugAssertion.errors.txt.diff
-compiler/prettyFileWithErrorsAndTabs.errors.txt.diff
 compiler/manyCompilerErrorsInTheTwoFiles.errors.txt.diff
 
 ## "Call signature return type" layer removed from error pyramid

From e60dc774a2e1783d8cde866454ba6196cac995da Mon Sep 17 00:00:00 2001
From: John Favret <64748847+johnfav03@users.noreply.github.com>
Date: Thu, 20 Aug 2026 16:48:14 -0500
Subject: [PATCH 2/6] restore config baseline spacing

---
 tsc/internal/tsoptions/tsconfigparsing_test.go            | 8 ++------
 ...mat jsconfig.json to typeAcquisition  with json api.js | 1 +
 ...ig.json to typeAcquisition  with jsonSourceFile api.js | 1 +
 ...mat tsconfig.json to typeAcquisition  with json api.js | 1 +
 ...ig.json to typeAcquisition  with jsonSourceFile api.js | 1 +
 ...rrors for directory with no .ts files with json api.js | 1 +
 ...directory with no .ts files with jsonSourceFile api.js | 1 +
 .../generates errors for empty directory with json api.js | 1 +
 ... errors for empty directory with jsonSourceFile api.js | 1 +
 ... list when no references are provided with json api.js | 1 +
 ... no references are provided with jsonSourceFile api.js | 1 +
 ...generates errors for empty files list with json api.js | 1 +
 ...errors for empty files list with jsonSourceFile api.js | 1 +
 .../generates errors for empty include with json api.js   | 1 +
 ...es errors for empty include with jsonSourceFile api.js | 1 +
 ...nt directory after recursive wildcard with json api.js | 1 +
 ...ry after recursive wildcard with jsonSourceFile api.js | 1 +
 ...rates errors for includes with outDir with json api.js | 1 +
 ...rs for includes with outDir with jsonSourceFile api.js | 1 +
 ...hen commandline option is in tsconfig with json api.js | 1 +
 ...dline option is in tsconfig with jsonSourceFile api.js | 1 +
 ...rates errors when files is not string with json api.js | 1 +
 ...rs when files is not string with jsonSourceFile api.js | 1 +
 ...tes errors when include is not string with json api.js | 1 +
 ... when include is not string with jsonSourceFile api.js | 1 +
 .../reports error for an unknown option with json api.js  | 1 +
 ...error for an unknown option with jsonSourceFile api.js | 1 +
 ...rs for incorrectly cased option names with json api.js | 1 +
 ...orrectly cased option names with jsonSourceFile api.js | 1 +
 ...ng type option and invalid enum value with json api.js | 1 +
 ...tion and invalid enum value with jsonSourceFile api.js | 1 +
 ...ling suggestion for an unknown option with json api.js | 1 +
 ...stion for an unknown option with jsonSourceFile api.js | 1 +
 ...rns error when tsconfig have excludes with json api.js | 1 +
 ...when tsconfig have excludes with jsonSourceFile api.js | 1 +
 35 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/tsc/internal/tsoptions/tsconfigparsing_test.go b/tsc/internal/tsoptions/tsconfigparsing_test.go
index ead33c504486e..9b4d054bbacec 100644
--- a/tsc/internal/tsoptions/tsconfigparsing_test.go
+++ b/tsc/internal/tsoptions/tsconfigparsing_test.go
@@ -146,9 +146,7 @@ func TestParseConfigFileTextToJson(t *testing.T) {
 						UseCaseSensitiveFileNames: true,
 					},
 				})
-				if len(errors) == 0 {
-					baselineContent.WriteString("\n")
-				}
+				baselineContent.WriteString("\n")
 				if i != len(rec.input)-1 {
 					baselineContent.WriteString("\n")
 				}
@@ -1480,9 +1478,7 @@ func baselineParseConfigWith(t *testing.T, baselineFileName string, includeCompi
 				UseCaseSensitiveFileNames: true,
 			},
 		})
-		if len(parsedConfigFileContent.Errors) == 0 {
-			baselineContent.WriteString("\n")
-		}
+		baselineContent.WriteString("\n")
 		if i != len(input)-1 {
 			baselineContent.WriteString("\n")
 		}
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with json api.js
index 082733b22c032..7c34c87276cef 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with json api.js	
@@ -32,3 +32,4 @@ FileNames::
 /apath/a.ts,/apath/b.ts
 Errors::
 error TS17010: Unknown type acquisition option 'enableAutoDiscovy'.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with jsonSourceFile api.js
index a2da4c1909bb9..97ac7deef094f 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with jsonSourceFile api.js	
@@ -35,3 +35,4 @@ Errors::
 
 3   "enableAutoDiscovy": true,
     ~~~~~~~~~~~~~~~~~~~
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with json api.js
index ef39f5660ac17..8a0986bdadb62 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with json api.js	
@@ -26,3 +26,4 @@ FileNames::
 /apath/a.ts,/apath/b.ts
 Errors::
 error TS17010: Unknown type acquisition option 'enableAutoDiscovy'.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with jsonSourceFile api.js
index e25a3467059d0..5558dd2a1f1cb 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with jsonSourceFile api.js	
@@ -29,3 +29,4 @@ Errors::
 
 3   "enableAutoDiscovy": true,
     ~~~~~~~~~~~~~~~~~~~
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with json api.js
index cf7fe7917f062..997bf7716e28d 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with json api.js	
@@ -12,3 +12,4 @@ FileNames::
 
 Errors::
 error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with jsonSourceFile api.js
index cf7fe7917f062..997bf7716e28d 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with jsonSourceFile api.js	
@@ -12,3 +12,4 @@ FileNames::
 
 Errors::
 error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with json api.js
index f46c33ad62302..30621abe1050d 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with json api.js	
@@ -12,3 +12,4 @@ FileNames::
 
 Errors::
 error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with jsonSourceFile api.js
index f46c33ad62302..30621abe1050d 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with jsonSourceFile api.js	
@@ -12,3 +12,4 @@ FileNames::
 
 Errors::
 error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with json api.js
index 2686b9c407aad..9f5abbd52f4c4 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with json api.js	
@@ -14,3 +14,4 @@ FileNames::
 
 Errors::
 error TS18002: The 'files' list in config file '/apath/tsconfig.json' is empty.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with jsonSourceFile api.js
index 0db9e6e89e4d3..b3b115a909683 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with jsonSourceFile api.js	
@@ -17,3 +17,4 @@ Errors::
 
 2                 "files": [],
                            ~~
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with json api.js
index cf7944c9e280b..ae92900487d30 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with json api.js	
@@ -13,3 +13,4 @@ FileNames::
 
 Errors::
 error TS18002: The 'files' list in config file '/apath/tsconfig.json' is empty.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with jsonSourceFile api.js
index 2649820a5bf7d..51b3a5ec6f053 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with jsonSourceFile api.js	
@@ -16,3 +16,4 @@ Errors::
 
 2                 "files": []
                            ~~
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with json api.js
index 1f0351e2dabe5..b22486c178a36 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with json api.js	
@@ -13,3 +13,4 @@ FileNames::
 
 Errors::
 error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[]' and 'exclude' paths were '[]'.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with jsonSourceFile api.js
index 1f0351e2dabe5..b22486c178a36 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with jsonSourceFile api.js	
@@ -13,3 +13,4 @@ FileNames::
 
 Errors::
 error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[]' and 'exclude' paths were '[]'.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with json api.js
index 90013462152b5..0cc47503753c8 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with json api.js	
@@ -14,3 +14,4 @@ FileNames::
 Errors::
 error TS5065: File specification cannot contain a parent directory ('..') that appears after a recursive directory wildcard ('**'): '**/../*.ts'.
 error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/../*.ts"]' and 'exclude' paths were '[]'.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with jsonSourceFile api.js
index e70c343768f58..91aca843db251 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with jsonSourceFile api.js	
@@ -17,3 +17,4 @@ Errors::
 2                 "include": ["**/../*.ts"]
                               ~~~~~~~~~~~~
 error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/../*.ts"]' and 'exclude' paths were '[]'.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with json api.js
index 6bfe4f41ed6f7..fd6a9ae4ac50e 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with json api.js	
@@ -16,3 +16,4 @@ FileNames::
 
 Errors::
 error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '["/apath"]'.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with jsonSourceFile api.js
index 6bfe4f41ed6f7..fd6a9ae4ac50e 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with jsonSourceFile api.js	
@@ -16,3 +16,4 @@ FileNames::
 
 Errors::
 error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '["/apath"]'.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with json api.js
index 600f42a73c123..26382641787bb 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with json api.js	
@@ -15,3 +15,4 @@ FileNames::
 /apath/a.ts
 Errors::
 error TS6266: Option 'help' can only be specified on command line.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with jsonSourceFile api.js
index c4968e277a0e8..b33d215d5c225 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with jsonSourceFile api.js	
@@ -18,3 +18,4 @@ Errors::
 
 3     "help": true
       ~~~~~~
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with json api.js
index 3c0c6e0806db4..84e229b6d89fc 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with json api.js	
@@ -20,3 +20,4 @@ FileNames::
 
 Errors::
 error TS5024: Compiler option 'files' requires a value of type string.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with jsonSourceFile api.js
index 6d7916c01e0a1..db8d6cd9d8c5a 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with jsonSourceFile api.js	
@@ -30,3 +30,4 @@ Errors::
     ~~~~~~~
   8     }
     ~~~~~
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with json api.js
index 16c08f98d6ef2..e4e6af740d50a 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with json api.js	
@@ -18,3 +18,4 @@ FileNames::
 Errors::
 error TS5024: Compiler option 'include' requires a value of type string.
 error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[["./**/*.ts"]]' and 'exclude' paths were '[]'.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with jsonSourceFile api.js
index c7202d0880dba..14386748b3be6 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with jsonSourceFile api.js	
@@ -25,3 +25,4 @@ Errors::
 5     ]
   ~~~~~
 error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[["./**/*.ts"]]' and 'exclude' paths were '[]'.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with json api.js
index bd5f035edcff4..ca5b9b0e7f5bb 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with json api.js	
@@ -15,3 +15,4 @@ FileNames::
 /app.ts
 Errors::
 error TS5023: Unknown compiler option 'unknown'.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with jsonSourceFile api.js
index 9741d7f77e99d..b076bb4ed9c79 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with jsonSourceFile api.js	
@@ -18,3 +18,4 @@ Errors::
 
 3     "unknown": true
       ~~~~~~~~~
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with json api.js
index 45bbfe8a2a669..fe83886909fe4 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with json api.js	
@@ -41,3 +41,4 @@ Errors::
 error TS5025: Unknown compiler option 'moduledetection'. Did you mean 'moduleDetection'?
 error TS5025: Unknown compiler option 'skiplibcheck'. Did you mean 'skipLibCheck'?
 error TS5025: Unknown compiler option 'checkjs'. Did you mean 'checkJs'?
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with jsonSourceFile api.js
index e3e0b5592d815..41a5b1a2bf7d9 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with jsonSourceFile api.js	
@@ -71,3 +71,4 @@ Errors::
 
 12     "checkjs": true
        ~~~~~~~~~
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with json api.js
index 5c3e71d5b20a1..f51e477c660e1 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with json api.js	
@@ -19,3 +19,4 @@ Errors::
 error TS6046: Argument for '--target' option must be: 'es6', 'es2015', 'es2016', 'es2017', 'es2018', 'es2019', 'es2020', 'es2021', 'es2022', 'es2023', 'es2024', 'es2025', 'esnext'.
 error TS5024: Compiler option 'removeComments' requires a value of type boolean.
 error TS6046: Argument for '--moduleResolution' option must be: 'node16', 'nodenext', 'bundler'.
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with jsonSourceFile api.js
index d20dc3e2f0575..422e4c3c9f352 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with jsonSourceFile api.js	
@@ -28,3 +28,4 @@ Errors::
 
 5     "moduleResolution": "invalid value"
                           ~~~~~~~~~~~~~~~
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with json api.js
index 9991b2ef71eb0..a5d32b708c15d 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with json api.js	
@@ -15,3 +15,4 @@ FileNames::
 /app.ts
 Errors::
 error TS5025: Unknown compiler option 'targt'. Did you mean 'target'?
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with jsonSourceFile api.js
index 8159111918760..882a1f6ce8a81 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with jsonSourceFile api.js	
@@ -18,3 +18,4 @@ Errors::
 
 3     "targt": 1
       ~~~~~~~
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with json api.js
index 087df87cdbb43..eb0f0e1d547cb 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with json api.js	
@@ -21,3 +21,4 @@ FileNames::
 /apath/foge.ts,/apath/test.ts
 Errors::
 error TS6114: Unknown option 'excludes'. Did you mean 'exclude'?
+
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with jsonSourceFile api.js
index f308c3fe49528..7e0de849d67b8 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with jsonSourceFile api.js	
@@ -24,3 +24,4 @@ Errors::
 
 5                     "excludes": [
                       ~~~~~~~~~~
+

From ee667c52e850c112cb8d18c4afc4d59f54b257a1 Mon Sep 17 00:00:00 2001
From: John Favret <64748847+johnfav03@users.noreply.github.com>
Date: Thu, 20 Aug 2026 17:26:08 -0500
Subject: [PATCH 3/6] addressed feedback

---
 tsc/internal/api/format_diagnostics.go        |   2 +-
 .../diagnosticwriter/diagnosticwriter.go      |  49 ++++++-
 ...ntMapperDiagnosticDirectives.contentmapper |   5 +
 .../contentMapperDiagnostics.contentmapper    |   2 +
 ...rInvalidDiagnosticDirectives.contentmapper |   4 +
 .../deeplyNestedAssignabilityIssue.errors.txt |  15 +-
 ...uplicateIdentifierRelatedSpans1.errors.txt |  31 ++--
 ...uplicateIdentifierRelatedSpans2.errors.txt |  71 +++++-----
 ...uplicateIdentifierRelatedSpans3.errors.txt |  23 ++-
 ...uplicateIdentifierRelatedSpans4.errors.txt |  63 ++++-----
 ...uplicateIdentifierRelatedSpans5.errors.txt |  23 ++-
 ...uplicateIdentifierRelatedSpans6.errors.txt |  23 ++-
 ...uplicateIdentifierRelatedSpans7.errors.txt |  71 +++++-----
 ...opPrettyErrorRelatedInformation.errors.txt |   3 +-
 ...manyCompilerErrorsInTheTwoFiles.errors.txt |  18 +++
 .../prettyContextNotDebugAssertion.errors.txt |   3 +-
 .../prettyFileWithErrorsAndTabs.errors.txt    |   2 +
 ....json to typeAcquisition  with json api.js |   3 +-
 ....json to typeAcquisition  with json api.js |   3 +-
 ...rectory with no .ts files with json api.js |   3 +-
 ...th no .ts files with jsonSourceFile api.js |   3 +-
 ...rrors for empty directory with json api.js |   3 +-
 ...empty directory with jsonSourceFile api.js |   3 +-
 ...o references are provided with json api.js |   3 +-
 ...rors for empty files list with json api.js |   3 +-
 ... errors for empty include with json api.js |   3 +-
 ...r empty include with jsonSourceFile api.js |   3 +-
 ... after recursive wildcard with json api.js |   3 +-
 ...ursive wildcard with jsonSourceFile api.js |   4 +-
 ... for includes with outDir with json api.js |   3 +-
 ...des with outDir with jsonSourceFile api.js |   3 +-
 ...ine option is in tsconfig with json api.js |   3 +-
 ... when files is not string with json api.js |   3 +-
 ...hen include is not string with json api.js |   3 +-
 ...e is not string with jsonSourceFile api.js |   4 +-
 ...ror for an unknown option with json api.js |   3 +-
 ...rectly cased option names with json api.js |   3 +-
 ...ed option names with jsonSourceFile api.js |   9 ++
 ...on and invalid enum value with json api.js |   3 +-
 ...alid enum value with jsonSourceFile api.js |   2 +
 ...ion for an unknown option with json api.js |   3 +-
 ...en tsconfig have excludes with json api.js |   3 +-
 .../typedefCrossModule5.errors.txt            |  15 +-
 .../tsbuild/commandLine/bad-locale.js         |   1 -
 .../when-build-not-first-argument.js          |   2 -
 .../configFileErrors/missing-config-file.js   |   1 -
 .../when-tsconfig-extends-the-missing-file.js |   4 -
 ...ts-the-error-about-it-by-stopping-build.js |   1 -
 .../noCheck/dts-errors-with-incremental.js    |  18 +--
 .../reference/tsbuild/noCheck/dts-errors.js   |  18 +--
 .../tsbuild/noEmit/changes-composite.js       |  36 ++---
 .../noEmit/changes-incremental-declaration.js |  36 ++---
 .../tsbuild/noEmit/changes-incremental.js     |  36 ++---
 .../changes-with-initial-noEmit-composite.js  |   6 +-
 ...-initial-noEmit-incremental-declaration.js |   6 +-
 ...changes-with-initial-noEmit-incremental.js |   6 +-
 ...ble-changes-with-incremental-as-modules.js |   9 +-
 ...aration-enable-changes-with-incremental.js |   9 +-
 ...tion-enable-changes-with-multiple-files.js |  42 ++----
 ...-errors-with-declaration-enable-changes.js |   9 +-
 .../dts-errors-with-incremental-as-modules.js |  15 +-
 .../noEmit/dts-errors-with-incremental.js     |  15 +-
 .../reference/tsbuild/noEmit/dts-errors.js    |  15 +-
 ...rrors-with-declaration-with-incremental.js |   6 +-
 .../dts-errors-with-declaration.js            |   6 +-
 ...iles-belong-to-rootDir-and-is-composite.js |   3 -
 ...ied-but-not-all-files-belong-to-rootDir.js |   3 -
 ...ting-json-module-from-project-reference.js |   4 -
 ...t-in-not-build-order-doesnt-throw-error.js |   1 -
 ...t-in-not-build-order-doesnt-throw-error.js |   1 -
 ...ror-if-input-file-is-missing-with-force.js |   4 +-
 .../reports-error-if-input-file-is-missing.js |   4 +-
 ...rrors-when-test-does-not-reference-core.js |   6 +-
 ...ects-have-errors-with-stopBuildOnErrors.js |   6 +-
 .../demo/updates-with-circular-reference.js   |   1 -
 .../dts-errors-with-incremental-as-modules.js |  12 +-
 .../noEmit/dts-errors-with-incremental.js     |  12 +-
 .../tsbuildWatch/noEmit/dts-errors.js         |  12 +-
 ...Error-with-declaration-with-incremental.js |   6 +-
 .../noEmitOnError-with-declaration.js         |   6 +-
 ...ceError-when-file-with-no-error-changes.js |   6 +-
 ...ing-errors-only-changed-file-is-emitted.js |   3 +-
 ...tErrors-when-file-with-no-error-changes.js |   6 +-
 ...ixing-error-files-all-files-are-emitted.js |   3 +-
 ...e-down-stream-project-and-then-fixes-it.js |   3 +-
 .../works-with-extended-source-files.js       |   1 -
 .../reexport/Reports-errors-correctly.js      |   3 +-
 ...rrors-when-test-does-not-reference-core.js |   3 +-
 ...ects-have-errors-with-stopBuildOnErrors.js |   3 +-
 ...tches-config-files-that-are-not-present.js |   1 -
 ...ig-with-incorrect-compiler-option-value.js |   1 -
 ...TSConfig-with-incorrect-compiler-option.js |   1 -
 ...Initialized-TSConfig-with-tsconfig.json.js |   1 -
 .../commandLine/Parse-enum-type-options.js    |   1 -
 .../reference/tsc/commandLine/bad-locale.js   |   1 -
 ...nfig-in-different-folder-does-not-exist.js |   1 -
 ...ionless-file-in-tsconfig-does-not-exist.js |   4 +-
 .../extensionless-file-in-tsconfig-exists.js  |   4 +-
 ...tensionless-file-on-command-line-exists.js |   1 -
 .../file-in-tsconfig-does-not-exist.js        |   4 +-
 .../tsc/commandLine/non-object-config-root.js |   1 -
 ...ation-failure-reports-one-project-error.js |   1 -
 ...per-is-disabled-after-repeated-failures.js |   1 -
 ...ist-on-disk-that-differs-only-in-casing.js |   3 +-
 ...m-multiple-places-with-different-casing.js | 133 +++++++++---------
 ...ative-and-non-relative-file-resolutions.js |   6 +-
 ...e-with-multiple-files-and-complex-types.js |   3 +-
 ...-config-file-absent-with---ignoreConfig.js |   1 -
 ...oject-and-files-when-config-file-absent.js |   1 -
 ...g-project-and-files-with---ignoreConfig.js |   1 -
 .../ignoreConfig/mixing-project-and-files.js  |   1 -
 .../tsc/ignoreConfig/specifying-files.js      |   1 -
 ...-config-file-absent-with---ignoreConfig.js |   1 -
 ...cifying-project-when-config-file-absent.js |   1 -
 ...mental-with-case-insensitive-file-names.js |   3 +-
 ...ion-field-with-declaration-emit-enabled.js |   6 +-
 .../internal-symbolname-in-tsbuildInfo.js     |  24 ++--
 ...th-import-in-jsdoc-in-composite-project.js |   1 -
 .../incremental/serializing-error-chain.js    |   6 +-
 .../libraryResolution/when-noLib-toggles.js   |  10 --
 .../noCheck/dts-errors-with-incremental.js    |  18 +--
 .../reference/tsc/noCheck/dts-errors.js       |  18 +--
 .../reference/tsc/noEmit/changes-composite.js |  36 ++---
 .../noEmit/changes-incremental-declaration.js |  36 ++---
 .../tsc/noEmit/changes-incremental.js         |  36 ++---
 .../changes-with-initial-noEmit-composite.js  |   6 +-
 ...-initial-noEmit-incremental-declaration.js |   6 +-
 ...changes-with-initial-noEmit-incremental.js |   6 +-
 ...tion-enable-changes-with-multiple-files.js |  42 ++----
 .../dts-errors-with-incremental-as-modules.js |  15 +-
 .../tsc/noEmit/dts-errors-with-incremental.js |  15 +-
 .../reference/tsc/noEmit/dts-errors.js        |  15 +-
 ...rrors-with-declaration-with-incremental.js |   6 +-
 .../dts-errors-with-declaration.js            |   6 +-
 .../Default-initialized-TSConfig.js           |   1 -
 .../Show-TSConfig-with-advanced-options.js    |   1 -
 ...fig-with-boolean-value-compiler-options.js |   1 -
 ...Config-with-enum-value-compiler-options.js |   1 -
 ...ig-with-incorrect-compiler-option-value.js |   1 -
 ...TSConfig-with-incorrect-compiler-option.js |   1 -
 ...h-list-compiler-options-with-enum-value.js |   1 -
 ...how-TSConfig-with-list-compiler-options.js |   1 -
 .../parse-tsconfig-with-typeAcquisition.js    |   1 -
 ...sted-subdirectory-removed-and-recreated.js |   3 +-
 .../watch-handles-tsconfig-deleted.js         |   6 +-
 ...-with-tsconfig-files-list-entry-deleted.js |   4 +-
 .../reference/tscWatch/noEmit/dts-errors.js   |  12 +-
 tsc/testdata/submoduleAccepted.txt            |   3 +
 148 files changed, 591 insertions(+), 846 deletions(-)

diff --git a/tsc/internal/api/format_diagnostics.go b/tsc/internal/api/format_diagnostics.go
index 83162229983d7..4f735a4a7a2bc 100644
--- a/tsc/internal/api/format_diagnostics.go
+++ b/tsc/internal/api/format_diagnostics.go
@@ -46,7 +46,7 @@ func (s *Session) handleFormatDiagnostics(ctx context.Context, params *FormatDia
 
 	var sb strings.Builder
 	if colorAndContext {
-		diagnosticwriter.FormatDiagnosticsWithColorAndContext(&sb, diags, formatOpts)
+		diagnosticwriter.FormatDiagnosticsWithColorAndContextForAPI(&sb, diags, formatOpts)
 	} else {
 		diagnosticwriter.WriteFormatDiagnostics(&sb, diags, formatOpts)
 	}
diff --git a/tsc/internal/diagnosticwriter/diagnosticwriter.go b/tsc/internal/diagnosticwriter/diagnosticwriter.go
index 01626fb62a962..7abd29ad063c7 100644
--- a/tsc/internal/diagnosticwriter/diagnosticwriter.go
+++ b/tsc/internal/diagnosticwriter/diagnosticwriter.go
@@ -199,7 +199,13 @@ const (
 )
 
 func FormatDiagnosticsWithColorAndContext(output io.Writer, diags []Diagnostic, formatOpts *FormattingOptions) {
-	for _, diagnostic := range diags {
+	if len(diags) == 0 {
+		return
+	}
+	for i, diagnostic := range diags {
+		if i > 0 {
+			fmt.Fprint(output, formatOpts.NewLine)
+		}
 		FormatDiagnosticWithColorAndContext(output, diagnostic, formatOpts)
 	}
 }
@@ -216,6 +222,47 @@ func FormatDiagnosticWithColorAndContext(output io.Writer, diagnostic Diagnostic
 	fmt.Fprintf(output, "%s %s%d: %s", foregroundColorEscapeGrey, diagnosticPrefix(diagnostic), diagnostic.Code(), resetEscapeSequence)
 	WriteFlattenedDiagnosticMessage(output, diagnostic, formatOpts.NewLine, formatOpts.Locale)
 
+	if diagnostic.File() != nil && diagnostic.Code() != diagnostics.File_appears_to_be_binary.Code() {
+		fmt.Fprint(output, formatOpts.NewLine)
+		writeCodeSnippet(output, diagnostic.File(), diagnostic.Pos(), diagnostic.Len(), getCategoryFormat(diagnostic.Category()), "", formatOpts)
+		fmt.Fprint(output, formatOpts.NewLine)
+	}
+
+	if (diagnostic.RelatedInformation() != nil) && (len(diagnostic.RelatedInformation()) > 0) {
+		for _, relatedInformation := range diagnostic.RelatedInformation() {
+			file := relatedInformation.File()
+			if file != nil {
+				fmt.Fprint(output, formatOpts.NewLine)
+				fmt.Fprint(output, "  ")
+				pos := relatedInformation.Pos()
+				WriteLocation(output, file, pos, formatOpts, writeWithStyleAndReset)
+				fmt.Fprint(output, " - ")
+				WriteFlattenedDiagnosticMessage(output, relatedInformation, formatOpts.NewLine, formatOpts.Locale)
+				writeCodeSnippet(output, file, pos, relatedInformation.Len(), foregroundColorEscapeCyan, "    ", formatOpts)
+			}
+			fmt.Fprint(output, formatOpts.NewLine)
+		}
+	}
+}
+
+func FormatDiagnosticsWithColorAndContextForAPI(output io.Writer, diags []Diagnostic, formatOpts *FormattingOptions) {
+	for _, diagnostic := range diags {
+		formatDiagnosticWithColorAndContextForAPI(output, diagnostic, formatOpts)
+	}
+}
+
+func formatDiagnosticWithColorAndContextForAPI(output io.Writer, diagnostic Diagnostic, formatOpts *FormattingOptions) {
+	if diagnostic.File() != nil {
+		file := diagnostic.File()
+		pos := diagnostic.Pos()
+		WriteLocation(output, file, pos, formatOpts, writeWithStyleAndReset)
+		fmt.Fprint(output, " - ")
+	}
+
+	writeWithStyleAndReset(output, diagnostic.Category().Name(), getCategoryFormat(diagnostic.Category()))
+	fmt.Fprintf(output, "%s %s%d: %s", foregroundColorEscapeGrey, diagnosticPrefix(diagnostic), diagnostic.Code(), resetEscapeSequence)
+	WriteFlattenedDiagnosticMessage(output, diagnostic, formatOpts.NewLine, formatOpts.Locale)
+
 	if diagnostic.File() != nil && diagnostic.Code() != diagnostics.File_appears_to_be_binary.Code() {
 		fmt.Fprint(output, formatOpts.NewLine)
 		writeCodeSnippet(output, diagnostic.File(), diagnostic.Pos(), diagnostic.Len(), getCategoryFormat(diagnostic.Category()), "", formatOpts)
diff --git a/tsc/testdata/baselines/reference/compiler/contentMapperDiagnosticDirectives.contentmapper b/tsc/testdata/baselines/reference/compiler/contentMapperDiagnosticDirectives.contentmapper
index b5a663f3e2199..aeafe71315828 100644
--- a/tsc/testdata/baselines/reference/compiler/contentMapperDiagnosticDirectives.contentmapper
+++ b/tsc/testdata/baselines/reference/compiler/contentMapperDiagnosticDirectives.contentmapper
@@ -41,22 +41,27 @@ export const broken = undefined
 
 7 // @box-expect-error: Syntax errors do not satisfy expectations.
   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
 /widget.box:10:1 - error box2578: Unused second expectation.
 
 10 // @box-expect-error: Unused second expectation.
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
 /widget.box:8:21 - error TS1109: Expression expected.
 
 8 const syntaxError = ;
                       ~
+
 /widget.box:13:7 - error TS2322: Type 'string' is not assignable to type 'number'.
 
 13 const visible: number = "wrong";
          ~~~~~~~
+
 /widget.box:15:1 - error box2578: Mapper diagnostics do not satisfy expectations.
 
 15 // @box-expect-error: Mapper diagnostics do not satisfy expectations.
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
 /widget.box:16:23 - error box1000: Unclosed interpolation.
 
 16 export const broken = #{unterminated;
diff --git a/tsc/testdata/baselines/reference/compiler/contentMapperDiagnostics.contentmapper b/tsc/testdata/baselines/reference/compiler/contentMapperDiagnostics.contentmapper
index 088e43b12d109..223287609cb54 100644
--- a/tsc/testdata/baselines/reference/compiler/contentMapperDiagnostics.contentmapper
+++ b/tsc/testdata/baselines/reference/compiler/contentMapperDiagnostics.contentmapper
@@ -15,10 +15,12 @@ export const broken = undefined
 
 1 export const count: number = "not a number";
                ~~~~~
+
 /widget.box:2:14 - error TS2322: Type 'number' is not assignable to type 'string'.
 
 2 export const label: string = #{target};
                ~~~~~
+
 /widget.box:3:23 - error box1000: Unclosed interpolation.
 
 3 export const broken = #{unterminated;
diff --git a/tsc/testdata/baselines/reference/compiler/contentMapperInvalidDiagnosticDirectives.contentmapper b/tsc/testdata/baselines/reference/compiler/contentMapperInvalidDiagnosticDirectives.contentmapper
index 9c5858339f865..8ea467db00dd4 100644
--- a/tsc/testdata/baselines/reference/compiler/contentMapperInvalidDiagnosticDirectives.contentmapper
+++ b/tsc/testdata/baselines/reference/compiler/contentMapperInvalidDiagnosticDirectives.contentmapper
@@ -30,21 +30,25 @@
 
 1 
   ~
+
 /invalidPolicy.invalidpolicy:1:1 - error TS100025: The content mapper 'mapper' failed to transform this file.
   The content mapper returned a diagnostic directive with invalid policy '2'.
 
 1 
   ~
+
 /invalidRange.invalidrange:1:1 - error TS100025: The content mapper 'mapper' failed to transform this file.
   Diagnostic directive 0 returned by the content mapper has an invalid range.
 
 1 
   ~
+
 /invalidUnusedDiagnosticIndex.invalidunusedindex:1:1 - error TS100025: The content mapper 'mapper' failed to transform this file.
   Diagnostic directive 0 returned by the content mapper has an invalid 'unusedExpectDirectiveIndex'.
 
 1 
   ~
+
 /overlap.overlap:1:1 - error TS100025: The content mapper 'mapper' failed to transform this file.
   The content mapper returned diagnostic directives with overlapping virtual ranges.
 
diff --git a/tsc/testdata/baselines/reference/compiler/deeplyNestedAssignabilityIssue.errors.txt b/tsc/testdata/baselines/reference/compiler/deeplyNestedAssignabilityIssue.errors.txt
index 5add2fd996c3a..27a65bedc6dbd 100644
--- a/tsc/testdata/baselines/reference/compiler/deeplyNestedAssignabilityIssue.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/deeplyNestedAssignabilityIssue.errors.txt
@@ -3,27 +3,26 @@
 22                 thing: {}
                    ~~~~~
 
-  deeplyNestedAssignabilityIssue.ts:2:5
+  deeplyNestedAssignabilityIssue.ts:2:5 - 'a' is declared here.
     2     a: number;
           ~
-    'a' is declared here.
-  deeplyNestedAssignabilityIssue.ts:9:17
+
+  deeplyNestedAssignabilityIssue.ts:9:17 - The expected type comes from property 'thing' which is declared here on type '{ thing: A; }'
     9                 thing: A;
                       ~~~~~
-    The expected type comes from property 'thing' which is declared here on type '{ thing: A; }'
+
 deeplyNestedAssignabilityIssue.ts:25:17 - error TS2741: Property 'a' is missing in type '{}' but required in type 'A'.
 
 25                 another: {}
                    ~~~~~~~
 
-  deeplyNestedAssignabilityIssue.ts:2:5
+  deeplyNestedAssignabilityIssue.ts:2:5 - 'a' is declared here.
     2     a: number;
           ~
-    'a' is declared here.
-  deeplyNestedAssignabilityIssue.ts:12:17
+
+  deeplyNestedAssignabilityIssue.ts:12:17 - The expected type comes from property 'another' which is declared here on type '{ another: A; }'
     12                 another: A;
                        ~~~~~~~
-    The expected type comes from property 'another' which is declared here on type '{ another: A; }'
 
 
 ==== deeplyNestedAssignabilityIssue.ts (2 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans1.errors.txt b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans1.errors.txt
index 9af458a195d63..bf30f2c3fc40c 100644
--- a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans1.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans1.errors.txt
@@ -3,63 +3,62 @@
 1 class Foo { }
         ~~~
 
-  file2.ts:1:6
+  file2.ts:1:6 - 'Foo' was also declared here.
     1 type Foo = number;
            ~~~
-    'Foo' was also declared here.
-  file3.ts:1:6
+
+  file3.ts:1:6 - 'Foo' was also declared here.
     1 type Foo = 54;
            ~~~
-    'Foo' was also declared here.
+
 file1.ts:2:7 - error TS2451: Cannot redeclare block-scoped variable 'Bar'.
 
 2 const Bar = 3;
         ~~~
 
-  file2.ts:2:7
+  file2.ts:2:7 - 'Bar' was also declared here.
     2 class Bar {}
             ~~~
-    'Bar' was also declared here.
-  file3.ts:2:5
+
+  file3.ts:2:5 - 'Bar' was also declared here.
     2 let Bar = 42
           ~~~
-    'Bar' was also declared here.
+
 file2.ts:1:6 - error TS2300: Duplicate identifier 'Foo'.
 
 1 type Foo = number;
        ~~~
 
-  file1.ts:1:7
+  file1.ts:1:7 - 'Foo' was also declared here.
     1 class Foo { }
             ~~~
-    'Foo' was also declared here.
+
 file2.ts:2:7 - error TS2451: Cannot redeclare block-scoped variable 'Bar'.
 
 2 class Bar {}
         ~~~
 
-  file1.ts:2:7
+  file1.ts:2:7 - 'Bar' was also declared here.
     2 const Bar = 3;
             ~~~
-    'Bar' was also declared here.
+
 file3.ts:1:6 - error TS2300: Duplicate identifier 'Foo'.
 
 1 type Foo = 54;
        ~~~
 
-  file1.ts:1:7
+  file1.ts:1:7 - 'Foo' was also declared here.
     1 class Foo { }
             ~~~
-    'Foo' was also declared here.
+
 file3.ts:2:5 - error TS2451: Cannot redeclare block-scoped variable 'Bar'.
 
 2 let Bar = 42
       ~~~
 
-  file1.ts:2:7
+  file1.ts:2:7 - 'Bar' was also declared here.
     2 const Bar = 3;
             ~~~
-    'Bar' was also declared here.
 
 
 ==== file1.ts (2 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans2.errors.txt b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans2.errors.txt
index 69e8f479c68ec..f26290ce4096f 100644
--- a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans2.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans2.errors.txt
@@ -3,163 +3,162 @@
 1 class A { }
         ~
 
-  file2.ts:1:7
+  file2.ts:1:7 - 'A' was also declared here.
     1 class A { }
             ~
-    'A' was also declared here.
+
 file1.ts:2:7 - error TS2300: Duplicate identifier 'B'.
 
 2 class B { }
         ~
 
-  file2.ts:2:7
+  file2.ts:2:7 - 'B' was also declared here.
     2 class B { }
             ~
-    'B' was also declared here.
+
 file1.ts:3:7 - error TS2300: Duplicate identifier 'C'.
 
 3 class C { }
         ~
 
-  file2.ts:3:7
+  file2.ts:3:7 - 'C' was also declared here.
     3 class C { }
             ~
-    'C' was also declared here.
+
 file1.ts:4:7 - error TS2300: Duplicate identifier 'D'.
 
 4 class D { }
         ~
 
-  file2.ts:4:7
+  file2.ts:4:7 - 'D' was also declared here.
     4 class D { }
             ~
-    'D' was also declared here.
+
 file1.ts:5:7 - error TS2300: Duplicate identifier 'E'.
 
 5 class E { }
         ~
 
-  file2.ts:5:7
+  file2.ts:5:7 - 'E' was also declared here.
     5 class E { }
             ~
-    'E' was also declared here.
+
 file1.ts:6:7 - error TS2300: Duplicate identifier 'F'.
 
 6 class F { }
         ~
 
-  file2.ts:6:7
+  file2.ts:6:7 - 'F' was also declared here.
     6 class F { }
             ~
-    'F' was also declared here.
+
 file1.ts:7:7 - error TS2300: Duplicate identifier 'G'.
 
 7 class G { }
         ~
 
-  file2.ts:7:7
+  file2.ts:7:7 - 'G' was also declared here.
     7 class G { }
             ~
-    'G' was also declared here.
+
 file1.ts:8:7 - error TS2300: Duplicate identifier 'H'.
 
 8 class H { }
         ~
 
-  file2.ts:8:7
+  file2.ts:8:7 - 'H' was also declared here.
     8 class H { }
             ~
-    'H' was also declared here.
+
 file1.ts:9:7 - error TS2300: Duplicate identifier 'I'.
 
 9 class I { }
         ~
 
-  file2.ts:9:7
+  file2.ts:9:7 - 'I' was also declared here.
     9 class I { }
             ~
-    'I' was also declared here.
+
 file2.ts:1:7 - error TS2300: Duplicate identifier 'A'.
 
 1 class A { }
         ~
 
-  file1.ts:1:7
+  file1.ts:1:7 - 'A' was also declared here.
     1 class A { }
             ~
-    'A' was also declared here.
+
 file2.ts:2:7 - error TS2300: Duplicate identifier 'B'.
 
 2 class B { }
         ~
 
-  file1.ts:2:7
+  file1.ts:2:7 - 'B' was also declared here.
     2 class B { }
             ~
-    'B' was also declared here.
+
 file2.ts:3:7 - error TS2300: Duplicate identifier 'C'.
 
 3 class C { }
         ~
 
-  file1.ts:3:7
+  file1.ts:3:7 - 'C' was also declared here.
     3 class C { }
             ~
-    'C' was also declared here.
+
 file2.ts:4:7 - error TS2300: Duplicate identifier 'D'.
 
 4 class D { }
         ~
 
-  file1.ts:4:7
+  file1.ts:4:7 - 'D' was also declared here.
     4 class D { }
             ~
-    'D' was also declared here.
+
 file2.ts:5:7 - error TS2300: Duplicate identifier 'E'.
 
 5 class E { }
         ~
 
-  file1.ts:5:7
+  file1.ts:5:7 - 'E' was also declared here.
     5 class E { }
             ~
-    'E' was also declared here.
+
 file2.ts:6:7 - error TS2300: Duplicate identifier 'F'.
 
 6 class F { }
         ~
 
-  file1.ts:6:7
+  file1.ts:6:7 - 'F' was also declared here.
     6 class F { }
             ~
-    'F' was also declared here.
+
 file2.ts:7:7 - error TS2300: Duplicate identifier 'G'.
 
 7 class G { }
         ~
 
-  file1.ts:7:7
+  file1.ts:7:7 - 'G' was also declared here.
     7 class G { }
             ~
-    'G' was also declared here.
+
 file2.ts:8:7 - error TS2300: Duplicate identifier 'H'.
 
 8 class H { }
         ~
 
-  file1.ts:8:7
+  file1.ts:8:7 - 'H' was also declared here.
     8 class H { }
             ~
-    'H' was also declared here.
+
 file2.ts:9:7 - error TS2300: Duplicate identifier 'I'.
 
 9 class I { }
         ~
 
-  file1.ts:9:7
+  file1.ts:9:7 - 'I' was also declared here.
     9 class I { }
             ~
-    'I' was also declared here.
 
 
 ==== file1.ts (9 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans3.errors.txt b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans3.errors.txt
index b08664db5ce5a..e61e71853317b 100644
--- a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans3.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans3.errors.txt
@@ -3,55 +3,54 @@
 2     duplicate1: () => string;
       ~~~~~~~~~~
 
-  file2.ts:2:5
+  file2.ts:2:5 - 'duplicate1' was also declared here.
     2     duplicate1(): number;
           ~~~~~~~~~~
-    'duplicate1' was also declared here.
+
 file1.ts:3:5 - error TS2300: Duplicate identifier 'duplicate2'.
 
 3     duplicate2: () => string;
       ~~~~~~~~~~
 
-  file2.ts:3:5
+  file2.ts:3:5 - 'duplicate2' was also declared here.
     3     duplicate2(): number;
           ~~~~~~~~~~
-    'duplicate2' was also declared here.
+
 file1.ts:4:5 - error TS2300: Duplicate identifier 'duplicate3'.
 
 4     duplicate3: () => string;
       ~~~~~~~~~~
 
-  file2.ts:4:5
+  file2.ts:4:5 - 'duplicate3' was also declared here.
     4     duplicate3(): number;
           ~~~~~~~~~~
-    'duplicate3' was also declared here.
+
 file2.ts:2:5 - error TS2300: Duplicate identifier 'duplicate1'.
 
 2     duplicate1(): number;
       ~~~~~~~~~~
 
-  file1.ts:2:5
+  file1.ts:2:5 - 'duplicate1' was also declared here.
     2     duplicate1: () => string;
           ~~~~~~~~~~
-    'duplicate1' was also declared here.
+
 file2.ts:3:5 - error TS2300: Duplicate identifier 'duplicate2'.
 
 3     duplicate2(): number;
       ~~~~~~~~~~
 
-  file1.ts:3:5
+  file1.ts:3:5 - 'duplicate2' was also declared here.
     3     duplicate2: () => string;
           ~~~~~~~~~~
-    'duplicate2' was also declared here.
+
 file2.ts:4:5 - error TS2300: Duplicate identifier 'duplicate3'.
 
 4     duplicate3(): number;
       ~~~~~~~~~~
 
-  file1.ts:4:5
+  file1.ts:4:5 - 'duplicate3' was also declared here.
     4     duplicate3: () => string;
           ~~~~~~~~~~
-    'duplicate3' was also declared here.
 
 
 ==== file1.ts (3 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans4.errors.txt b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans4.errors.txt
index c6088fa352d7c..3cf299fdb9d2e 100644
--- a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans4.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans4.errors.txt
@@ -3,145 +3,144 @@
 2     duplicate1: () => string;
       ~~~~~~~~~~
 
-  file2.ts:2:5
+  file2.ts:2:5 - 'duplicate1' was also declared here.
     2     duplicate1(): number;
           ~~~~~~~~~~
-    'duplicate1' was also declared here.
+
 file1.ts:3:5 - error TS2300: Duplicate identifier 'duplicate2'.
 
 3     duplicate2: () => string;
       ~~~~~~~~~~
 
-  file2.ts:3:5
+  file2.ts:3:5 - 'duplicate2' was also declared here.
     3     duplicate2(): number;
           ~~~~~~~~~~
-    'duplicate2' was also declared here.
+
 file1.ts:4:5 - error TS2300: Duplicate identifier 'duplicate3'.
 
 4     duplicate3: () => string;
       ~~~~~~~~~~
 
-  file2.ts:4:5
+  file2.ts:4:5 - 'duplicate3' was also declared here.
     4     duplicate3(): number;
           ~~~~~~~~~~
-    'duplicate3' was also declared here.
+
 file1.ts:5:5 - error TS2300: Duplicate identifier 'duplicate4'.
 
 5     duplicate4: () => string;
       ~~~~~~~~~~
 
-  file2.ts:5:5
+  file2.ts:5:5 - 'duplicate4' was also declared here.
     5     duplicate4(): number;
           ~~~~~~~~~~
-    'duplicate4' was also declared here.
+
 file1.ts:6:5 - error TS2300: Duplicate identifier 'duplicate5'.
 
 6     duplicate5: () => string;
       ~~~~~~~~~~
 
-  file2.ts:6:5
+  file2.ts:6:5 - 'duplicate5' was also declared here.
     6     duplicate5(): number;
           ~~~~~~~~~~
-    'duplicate5' was also declared here.
+
 file1.ts:7:5 - error TS2300: Duplicate identifier 'duplicate6'.
 
 7     duplicate6: () => string;
       ~~~~~~~~~~
 
-  file2.ts:7:5
+  file2.ts:7:5 - 'duplicate6' was also declared here.
     7     duplicate6(): number;
           ~~~~~~~~~~
-    'duplicate6' was also declared here.
+
 file1.ts:8:5 - error TS2300: Duplicate identifier 'duplicate7'.
 
 8     duplicate7: () => string;
       ~~~~~~~~~~
 
-  file2.ts:8:5
+  file2.ts:8:5 - 'duplicate7' was also declared here.
     8     duplicate7(): number;
           ~~~~~~~~~~
-    'duplicate7' was also declared here.
+
 file1.ts:9:5 - error TS2300: Duplicate identifier 'duplicate8'.
 
 9     duplicate8: () => string;
       ~~~~~~~~~~
 
-  file2.ts:9:5
+  file2.ts:9:5 - 'duplicate8' was also declared here.
     9     duplicate8(): number;
           ~~~~~~~~~~
-    'duplicate8' was also declared here.
+
 file2.ts:2:5 - error TS2300: Duplicate identifier 'duplicate1'.
 
 2     duplicate1(): number;
       ~~~~~~~~~~
 
-  file1.ts:2:5
+  file1.ts:2:5 - 'duplicate1' was also declared here.
     2     duplicate1: () => string;
           ~~~~~~~~~~
-    'duplicate1' was also declared here.
+
 file2.ts:3:5 - error TS2300: Duplicate identifier 'duplicate2'.
 
 3     duplicate2(): number;
       ~~~~~~~~~~
 
-  file1.ts:3:5
+  file1.ts:3:5 - 'duplicate2' was also declared here.
     3     duplicate2: () => string;
           ~~~~~~~~~~
-    'duplicate2' was also declared here.
+
 file2.ts:4:5 - error TS2300: Duplicate identifier 'duplicate3'.
 
 4     duplicate3(): number;
       ~~~~~~~~~~
 
-  file1.ts:4:5
+  file1.ts:4:5 - 'duplicate3' was also declared here.
     4     duplicate3: () => string;
           ~~~~~~~~~~
-    'duplicate3' was also declared here.
+
 file2.ts:5:5 - error TS2300: Duplicate identifier 'duplicate4'.
 
 5     duplicate4(): number;
       ~~~~~~~~~~
 
-  file1.ts:5:5
+  file1.ts:5:5 - 'duplicate4' was also declared here.
     5     duplicate4: () => string;
           ~~~~~~~~~~
-    'duplicate4' was also declared here.
+
 file2.ts:6:5 - error TS2300: Duplicate identifier 'duplicate5'.
 
 6     duplicate5(): number;
       ~~~~~~~~~~
 
-  file1.ts:6:5
+  file1.ts:6:5 - 'duplicate5' was also declared here.
     6     duplicate5: () => string;
           ~~~~~~~~~~
-    'duplicate5' was also declared here.
+
 file2.ts:7:5 - error TS2300: Duplicate identifier 'duplicate6'.
 
 7     duplicate6(): number;
       ~~~~~~~~~~
 
-  file1.ts:7:5
+  file1.ts:7:5 - 'duplicate6' was also declared here.
     7     duplicate6: () => string;
           ~~~~~~~~~~
-    'duplicate6' was also declared here.
+
 file2.ts:8:5 - error TS2300: Duplicate identifier 'duplicate7'.
 
 8     duplicate7(): number;
       ~~~~~~~~~~
 
-  file1.ts:8:5
+  file1.ts:8:5 - 'duplicate7' was also declared here.
     8     duplicate7: () => string;
           ~~~~~~~~~~
-    'duplicate7' was also declared here.
+
 file2.ts:9:5 - error TS2300: Duplicate identifier 'duplicate8'.
 
 9     duplicate8(): number;
       ~~~~~~~~~~
 
-  file1.ts:9:5
+  file1.ts:9:5 - 'duplicate8' was also declared here.
     9     duplicate8: () => string;
           ~~~~~~~~~~
-    'duplicate8' was also declared here.
 
 
 ==== file1.ts (8 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans5.errors.txt b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans5.errors.txt
index 558c71feb3c30..21f53eb8eb1a0 100644
--- a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans5.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans5.errors.txt
@@ -3,55 +3,54 @@
 3         duplicate1: () => string;
           ~~~~~~~~~~
 
-  file2.ts:4:9
+  file2.ts:4:9 - 'duplicate1' was also declared here.
     4         duplicate1(): number;
               ~~~~~~~~~~
-    'duplicate1' was also declared here.
+
 file1.ts:4:9 - error TS2300: Duplicate identifier 'duplicate2'.
 
 4         duplicate2: () => string;
           ~~~~~~~~~~
 
-  file2.ts:5:9
+  file2.ts:5:9 - 'duplicate2' was also declared here.
     5         duplicate2(): number;
               ~~~~~~~~~~
-    'duplicate2' was also declared here.
+
 file1.ts:5:9 - error TS2300: Duplicate identifier 'duplicate3'.
 
 5         duplicate3: () => string;
           ~~~~~~~~~~
 
-  file2.ts:6:9
+  file2.ts:6:9 - 'duplicate3' was also declared here.
     6         duplicate3(): number;
               ~~~~~~~~~~
-    'duplicate3' was also declared here.
+
 file2.ts:4:9 - error TS2300: Duplicate identifier 'duplicate1'.
 
 4         duplicate1(): number;
           ~~~~~~~~~~
 
-  file1.ts:3:9
+  file1.ts:3:9 - 'duplicate1' was also declared here.
     3         duplicate1: () => string;
               ~~~~~~~~~~
-    'duplicate1' was also declared here.
+
 file2.ts:5:9 - error TS2300: Duplicate identifier 'duplicate2'.
 
 5         duplicate2(): number;
           ~~~~~~~~~~
 
-  file1.ts:4:9
+  file1.ts:4:9 - 'duplicate2' was also declared here.
     4         duplicate2: () => string;
               ~~~~~~~~~~
-    'duplicate2' was also declared here.
+
 file2.ts:6:9 - error TS2300: Duplicate identifier 'duplicate3'.
 
 6         duplicate3(): number;
           ~~~~~~~~~~
 
-  file1.ts:5:9
+  file1.ts:5:9 - 'duplicate3' was also declared here.
     5         duplicate3: () => string;
               ~~~~~~~~~~
-    'duplicate3' was also declared here.
 
 
 ==== file1.ts (3 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans6.errors.txt b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans6.errors.txt
index f0c25f2c3ebcc..3466d69b043ff 100644
--- a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans6.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans6.errors.txt
@@ -3,55 +3,54 @@
 3         duplicate1: () => string;
           ~~~~~~~~~~
 
-  file2.ts:5:9
+  file2.ts:5:9 - 'duplicate1' was also declared here.
     5         duplicate1(): number;
               ~~~~~~~~~~
-    'duplicate1' was also declared here.
+
 file1.ts:4:9 - error TS2300: Duplicate identifier 'duplicate2'.
 
 4         duplicate2: () => string;
           ~~~~~~~~~~
 
-  file2.ts:6:9
+  file2.ts:6:9 - 'duplicate2' was also declared here.
     6         duplicate2(): number;
               ~~~~~~~~~~
-    'duplicate2' was also declared here.
+
 file1.ts:5:9 - error TS2300: Duplicate identifier 'duplicate3'.
 
 5         duplicate3: () => string;
           ~~~~~~~~~~
 
-  file2.ts:7:9
+  file2.ts:7:9 - 'duplicate3' was also declared here.
     7         duplicate3(): number;
               ~~~~~~~~~~
-    'duplicate3' was also declared here.
+
 file2.ts:5:9 - error TS2300: Duplicate identifier 'duplicate1'.
 
 5         duplicate1(): number;
           ~~~~~~~~~~
 
-  file1.ts:3:9
+  file1.ts:3:9 - 'duplicate1' was also declared here.
     3         duplicate1: () => string;
               ~~~~~~~~~~
-    'duplicate1' was also declared here.
+
 file2.ts:6:9 - error TS2300: Duplicate identifier 'duplicate2'.
 
 6         duplicate2(): number;
           ~~~~~~~~~~
 
-  file1.ts:4:9
+  file1.ts:4:9 - 'duplicate2' was also declared here.
     4         duplicate2: () => string;
               ~~~~~~~~~~
-    'duplicate2' was also declared here.
+
 file2.ts:7:9 - error TS2300: Duplicate identifier 'duplicate3'.
 
 7         duplicate3(): number;
           ~~~~~~~~~~
 
-  file1.ts:5:9
+  file1.ts:5:9 - 'duplicate3' was also declared here.
     5         duplicate3: () => string;
               ~~~~~~~~~~
-    'duplicate3' was also declared here.
 
 
 ==== file2.ts (3 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans7.errors.txt b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans7.errors.txt
index 4025d50fba249..9381fbbeed026 100644
--- a/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans7.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/duplicateIdentifierRelatedSpans7.errors.txt
@@ -3,163 +3,162 @@
 3         duplicate1: () => string;
           ~~~~~~~~~~
 
-  file2.ts:5:9
+  file2.ts:5:9 - 'duplicate1' was also declared here.
     5         duplicate1(): number;
               ~~~~~~~~~~
-    'duplicate1' was also declared here.
+
 file1.ts:4:9 - error TS2300: Duplicate identifier 'duplicate2'.
 
 4         duplicate2: () => string;
           ~~~~~~~~~~
 
-  file2.ts:6:9
+  file2.ts:6:9 - 'duplicate2' was also declared here.
     6         duplicate2(): number;
               ~~~~~~~~~~
-    'duplicate2' was also declared here.
+
 file1.ts:5:9 - error TS2300: Duplicate identifier 'duplicate3'.
 
 5         duplicate3: () => string;
           ~~~~~~~~~~
 
-  file2.ts:7:9
+  file2.ts:7:9 - 'duplicate3' was also declared here.
     7         duplicate3(): number;
               ~~~~~~~~~~
-    'duplicate3' was also declared here.
+
 file1.ts:6:9 - error TS2300: Duplicate identifier 'duplicate4'.
 
 6         duplicate4: () => string;
           ~~~~~~~~~~
 
-  file2.ts:8:9
+  file2.ts:8:9 - 'duplicate4' was also declared here.
     8         duplicate4(): number;
               ~~~~~~~~~~
-    'duplicate4' was also declared here.
+
 file1.ts:7:9 - error TS2300: Duplicate identifier 'duplicate5'.
 
 7         duplicate5: () => string;
           ~~~~~~~~~~
 
-  file2.ts:9:9
+  file2.ts:9:9 - 'duplicate5' was also declared here.
     9         duplicate5(): number;
               ~~~~~~~~~~
-    'duplicate5' was also declared here.
+
 file1.ts:8:9 - error TS2300: Duplicate identifier 'duplicate6'.
 
 8         duplicate6: () => string;
           ~~~~~~~~~~
 
-  file2.ts:10:9
+  file2.ts:10:9 - 'duplicate6' was also declared here.
     10         duplicate6(): number;
                ~~~~~~~~~~
-    'duplicate6' was also declared here.
+
 file1.ts:9:9 - error TS2300: Duplicate identifier 'duplicate7'.
 
 9         duplicate7: () => string;
           ~~~~~~~~~~
 
-  file2.ts:11:9
+  file2.ts:11:9 - 'duplicate7' was also declared here.
     11         duplicate7(): number;
                ~~~~~~~~~~
-    'duplicate7' was also declared here.
+
 file1.ts:10:9 - error TS2300: Duplicate identifier 'duplicate8'.
 
 10         duplicate8: () => string;
            ~~~~~~~~~~
 
-  file2.ts:12:9
+  file2.ts:12:9 - 'duplicate8' was also declared here.
     12         duplicate8(): number;
                ~~~~~~~~~~
-    'duplicate8' was also declared here.
+
 file1.ts:11:9 - error TS2300: Duplicate identifier 'duplicate9'.
 
 11         duplicate9: () => string;
            ~~~~~~~~~~
 
-  file2.ts:13:9
+  file2.ts:13:9 - 'duplicate9' was also declared here.
     13         duplicate9(): number;
                ~~~~~~~~~~
-    'duplicate9' was also declared here.
+
 file2.ts:5:9 - error TS2300: Duplicate identifier 'duplicate1'.
 
 5         duplicate1(): number;
           ~~~~~~~~~~
 
-  file1.ts:3:9
+  file1.ts:3:9 - 'duplicate1' was also declared here.
     3         duplicate1: () => string;
               ~~~~~~~~~~
-    'duplicate1' was also declared here.
+
 file2.ts:6:9 - error TS2300: Duplicate identifier 'duplicate2'.
 
 6         duplicate2(): number;
           ~~~~~~~~~~
 
-  file1.ts:4:9
+  file1.ts:4:9 - 'duplicate2' was also declared here.
     4         duplicate2: () => string;
               ~~~~~~~~~~
-    'duplicate2' was also declared here.
+
 file2.ts:7:9 - error TS2300: Duplicate identifier 'duplicate3'.
 
 7         duplicate3(): number;
           ~~~~~~~~~~
 
-  file1.ts:5:9
+  file1.ts:5:9 - 'duplicate3' was also declared here.
     5         duplicate3: () => string;
               ~~~~~~~~~~
-    'duplicate3' was also declared here.
+
 file2.ts:8:9 - error TS2300: Duplicate identifier 'duplicate4'.
 
 8         duplicate4(): number;
           ~~~~~~~~~~
 
-  file1.ts:6:9
+  file1.ts:6:9 - 'duplicate4' was also declared here.
     6         duplicate4: () => string;
               ~~~~~~~~~~
-    'duplicate4' was also declared here.
+
 file2.ts:9:9 - error TS2300: Duplicate identifier 'duplicate5'.
 
 9         duplicate5(): number;
           ~~~~~~~~~~
 
-  file1.ts:7:9
+  file1.ts:7:9 - 'duplicate5' was also declared here.
     7         duplicate5: () => string;
               ~~~~~~~~~~
-    'duplicate5' was also declared here.
+
 file2.ts:10:9 - error TS2300: Duplicate identifier 'duplicate6'.
 
 10         duplicate6(): number;
            ~~~~~~~~~~
 
-  file1.ts:8:9
+  file1.ts:8:9 - 'duplicate6' was also declared here.
     8         duplicate6: () => string;
               ~~~~~~~~~~
-    'duplicate6' was also declared here.
+
 file2.ts:11:9 - error TS2300: Duplicate identifier 'duplicate7'.
 
 11         duplicate7(): number;
            ~~~~~~~~~~
 
-  file1.ts:9:9
+  file1.ts:9:9 - 'duplicate7' was also declared here.
     9         duplicate7: () => string;
               ~~~~~~~~~~
-    'duplicate7' was also declared here.
+
 file2.ts:12:9 - error TS2300: Duplicate identifier 'duplicate8'.
 
 12         duplicate8(): number;
            ~~~~~~~~~~
 
-  file1.ts:10:9
+  file1.ts:10:9 - 'duplicate8' was also declared here.
     10         duplicate8: () => string;
                ~~~~~~~~~~
-    'duplicate8' was also declared here.
+
 file2.ts:13:9 - error TS2300: Duplicate identifier 'duplicate9'.
 
 13         duplicate9(): number;
            ~~~~~~~~~~
 
-  file1.ts:11:9
+  file1.ts:11:9 - 'duplicate9' was also declared here.
     11         duplicate9: () => string;
                ~~~~~~~~~~
-    'duplicate9' was also declared here.
 
 
 ==== file2.ts (9 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/esModuleInteropPrettyErrorRelatedInformation.errors.txt b/tsc/testdata/baselines/reference/compiler/esModuleInteropPrettyErrorRelatedInformation.errors.txt
index d17bb54d2aa2f..0fb5881599cf4 100644
--- a/tsc/testdata/baselines/reference/compiler/esModuleInteropPrettyErrorRelatedInformation.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/esModuleInteropPrettyErrorRelatedInformation.errors.txt
@@ -4,10 +4,9 @@
 3 invoke(foo);
          ~~~
 
-  index.ts:1:1
+  index.ts:1:1 - Type originates at this import. A namespace-style import cannot be called or constructed, and will cause a failure at runtime. Consider using a default import or import require here instead.
     1 import * as foo from "./foo";
       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-    Type originates at this import. A namespace-style import cannot be called or constructed, and will cause a failure at runtime. Consider using a default import or import require here instead.
 
 
 ==== foo.d.ts (0 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/manyCompilerErrorsInTheTwoFiles.errors.txt b/tsc/testdata/baselines/reference/compiler/manyCompilerErrorsInTheTwoFiles.errors.txt
index ca96d5ebf11b7..b7461fff03671 100644
--- a/tsc/testdata/baselines/reference/compiler/manyCompilerErrorsInTheTwoFiles.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/manyCompilerErrorsInTheTwoFiles.errors.txt
@@ -2,74 +2,92 @@
 
 1 const a =!@#!@$
              ~~
+
 a.ts:1:13 - error TS1134: Variable declaration expected.
 
 1 const a =!@#!@$
               ~
+
 a.ts:1:16 - error TS1109: Expression expected.
 
 1 const a =!@#!@$
                  ~
+
 a.ts:2:13 - error TS18026: '#!' can only be used at the start of a file.
 
 2 const b = !@#!@#!@#!
               ~~
+
 a.ts:2:14 - error TS1134: Variable declaration expected.
 
 2 const b = !@#!@#!@#!
                ~
+
 a.ts:2:16 - error TS18026: '#!' can only be used at the start of a file.
 
 2 const b = !@#!@#!@#!
                  ~~
+
 a.ts:2:19 - error TS18026: '#!' can only be used at the start of a file.
 
 2 const b = !@#!@#!@#!
                     ~~
+
 a.ts:3:1 - error TS2304: Cannot find name 'OK'.
 
 3 OK!
   ~~
+
 a.ts:4:1 - error TS1434: Unexpected keyword or identifier.
 
 4 HERE's A shouty thing
   ~~~~
+
 a.ts:4:1 - error TS2304: Cannot find name 'HERE'.
 
 4 HERE's A shouty thing
   ~~~~
+
 a.ts:4:22 - error TS1002: Unterminated string literal.
 
 4 HERE's A shouty thing
                        ~
+
 a.ts:5:1 - error TS1434: Unexpected keyword or identifier.
 
 5 GOTTA GO FAST
   ~~~~~
+
 a.ts:5:1 - error TS2304: Cannot find name 'GOTTA'.
 
 5 GOTTA GO FAST
   ~~~~~
+
 a.ts:5:7 - error TS1434: Unexpected keyword or identifier.
 
 5 GOTTA GO FAST
         ~~
+
 a.ts:5:7 - error TS2304: Cannot find name 'GO'.
 
 5 GOTTA GO FAST
         ~~
+
 a.ts:5:10 - error TS2304: Cannot find name 'FAST'.
 
 5 GOTTA GO FAST
            ~~~~
+
 b.ts:1:1 - error TS2304: Cannot find name 'fhqwhgads'.
 
 1 fhqwhgads
   ~~~~~~~~~
+
 b.ts:2:1 - error TS2304: Cannot find name 'to'.
 
 2 to
   ~~
+
 b.ts:3:1 - error TS2304: Cannot find name 'limit'.
 
 3 limit
diff --git a/tsc/testdata/baselines/reference/compiler/prettyContextNotDebugAssertion.errors.txt b/tsc/testdata/baselines/reference/compiler/prettyContextNotDebugAssertion.errors.txt
index 7ed50695b4f32..2c68ee24aa16d 100644
--- a/tsc/testdata/baselines/reference/compiler/prettyContextNotDebugAssertion.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/prettyContextNotDebugAssertion.errors.txt
@@ -3,10 +3,9 @@
 2 
   ~
 
-  index.ts:1:11
+  index.ts:1:11 - The parser expected to find a '}' to match the '{' token here.
     1 if (true) {
                 ~
-    The parser expected to find a '}' to match the '{' token here.
 
 
 ==== index.ts (1 errors) ====
diff --git a/tsc/testdata/baselines/reference/compiler/prettyFileWithErrorsAndTabs.errors.txt b/tsc/testdata/baselines/reference/compiler/prettyFileWithErrorsAndTabs.errors.txt
index 38509fcc0902d..810c38262b7cb 100644
--- a/tsc/testdata/baselines/reference/compiler/prettyFileWithErrorsAndTabs.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/prettyFileWithErrorsAndTabs.errors.txt
@@ -2,10 +2,12 @@
 
 3   const x: string = 12;
           ~
+
 prettyFileWithErrorsAndTabs.ts:4:9 - error TS2322: Type 'number' is not assignable to type 'string'.
 
 4   const y: string = 12;
           ~
+
 prettyFileWithErrorsAndTabs.ts:5:9 - error TS2322: Type 'number' is not assignable to type 'string'.
 
 5   const z: string = 12;
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with json api.js
index 7c34c87276cef..8add78656eff9 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format jsconfig.json to typeAcquisition  with json api.js	
@@ -31,5 +31,4 @@ TypeAcquisition::
 FileNames::
 /apath/a.ts,/apath/b.ts
 Errors::
-error TS17010: Unknown type acquisition option 'enableAutoDiscovy'.
-
+error TS17010: Unknown type acquisition option 'enableAutoDiscovy'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with json api.js
index 8a0986bdadb62..d6e32be5ddbfe 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/Convert incorrect format tsconfig.json to typeAcquisition  with json api.js	
@@ -25,5 +25,4 @@ TypeAcquisition::
 FileNames::
 /apath/a.ts,/apath/b.ts
 Errors::
-error TS17010: Unknown type acquisition option 'enableAutoDiscovy'.
-
+error TS17010: Unknown type acquisition option 'enableAutoDiscovy'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with json api.js
index 997bf7716e28d..385937b528ec2 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with json api.js	
@@ -11,5 +11,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
-
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with jsonSourceFile api.js
index 997bf7716e28d..385937b528ec2 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for directory with no .ts files with jsonSourceFile api.js	
@@ -11,5 +11,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
-
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with json api.js
index 30621abe1050d..10da1e28a9f93 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with json api.js	
@@ -11,5 +11,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
-
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with jsonSourceFile api.js
index 30621abe1050d..10da1e28a9f93 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty directory with jsonSourceFile api.js	
@@ -11,5 +11,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
-
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with json api.js
index 9f5abbd52f4c4..e290c4c786d60 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list when no references are provided with json api.js	
@@ -13,5 +13,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18002: The 'files' list in config file '/apath/tsconfig.json' is empty.
-
+error TS18002: The 'files' list in config file '/apath/tsconfig.json' is empty.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with json api.js
index ae92900487d30..d6c070663e130 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty files list with json api.js	
@@ -12,5 +12,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18002: The 'files' list in config file '/apath/tsconfig.json' is empty.
-
+error TS18002: The 'files' list in config file '/apath/tsconfig.json' is empty.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with json api.js
index b22486c178a36..9b23e6b9e8585 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with json api.js	
@@ -12,5 +12,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[]' and 'exclude' paths were '[]'.
-
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with jsonSourceFile api.js
index b22486c178a36..9b23e6b9e8585 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for empty include with jsonSourceFile api.js	
@@ -12,5 +12,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[]' and 'exclude' paths were '[]'.
-
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with json api.js
index 0cc47503753c8..348ef1309a490 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with json api.js	
@@ -13,5 +13,4 @@ FileNames::
 
 Errors::
 error TS5065: File specification cannot contain a parent directory ('..') that appears after a recursive directory wildcard ('**'): '**/../*.ts'.
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/../*.ts"]' and 'exclude' paths were '[]'.
-
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/../*.ts"]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with jsonSourceFile api.js
index 91aca843db251..fd1b7ee08c416 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for include with parent directory after recursive wildcard with jsonSourceFile api.js	
@@ -16,5 +16,5 @@ Errors::
 
 2                 "include": ["**/../*.ts"]
                               ~~~~~~~~~~~~
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/../*.ts"]' and 'exclude' paths were '[]'.
-
+
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/../*.ts"]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with json api.js
index fd6a9ae4ac50e..6224f4c9e1c6c 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with json api.js	
@@ -15,5 +15,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '["/apath"]'.
-
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '["/apath"]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with jsonSourceFile api.js
index fd6a9ae4ac50e..6224f4c9e1c6c 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors for includes with outDir with jsonSourceFile api.js	
@@ -15,5 +15,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '["/apath"]'.
-
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '["/apath"]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with json api.js
index 26382641787bb..687d07172e1c5 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when commandline option is in tsconfig with json api.js	
@@ -14,5 +14,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 /apath/a.ts
 Errors::
-error TS6266: Option 'help' can only be specified on command line.
-
+error TS6266: Option 'help' can only be specified on command line.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with json api.js
index 84e229b6d89fc..862250c5c77e5 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when files is not string with json api.js	
@@ -19,5 +19,4 @@ configFileName:: /apath/tsconfig.json
 FileNames::
 
 Errors::
-error TS5024: Compiler option 'files' requires a value of type string.
-
+error TS5024: Compiler option 'files' requires a value of type string.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with json api.js
index e4e6af740d50a..70c5e06e9eed9 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with json api.js	
@@ -17,5 +17,4 @@ FileNames::
 
 Errors::
 error TS5024: Compiler option 'include' requires a value of type string.
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[["./**/*.ts"]]' and 'exclude' paths were '[]'.
-
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[["./**/*.ts"]]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with jsonSourceFile api.js
index 14386748b3be6..b80ebe19dbb9d 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/generates errors when include is not string with jsonSourceFile api.js	
@@ -24,5 +24,5 @@ Errors::
   ~~~~~~~~~~~~~~~~~
 5     ]
   ~~~~~
-error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[["./**/*.ts"]]' and 'exclude' paths were '[]'.
-
+
+error TS18003: No inputs were found in config file '/apath/tsconfig.json'. Specified 'include' paths were '[["./**/*.ts"]]' and 'exclude' paths were '[]'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with json api.js
index ca5b9b0e7f5bb..d07c2c117ec84 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports error for an unknown option with json api.js	
@@ -14,5 +14,4 @@ configFileName:: tsconfig.json
 FileNames::
 /app.ts
 Errors::
-error TS5023: Unknown compiler option 'unknown'.
-
+error TS5023: Unknown compiler option 'unknown'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with json api.js
index fe83886909fe4..fb63985a902e6 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with json api.js	
@@ -40,5 +40,4 @@ Errors::
 error TS5025: Unknown compiler option 'nouncheckedsideeffectimports'. Did you mean 'noUncheckedSideEffectImports'?
 error TS5025: Unknown compiler option 'moduledetection'. Did you mean 'moduleDetection'?
 error TS5025: Unknown compiler option 'skiplibcheck'. Did you mean 'skipLibCheck'?
-error TS5025: Unknown compiler option 'checkjs'. Did you mean 'checkJs'?
-
+error TS5025: Unknown compiler option 'checkjs'. Did you mean 'checkJs'?
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with jsonSourceFile api.js
index 41a5b1a2bf7d9..b0719d4b7f4cf 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for incorrectly cased option names with jsonSourceFile api.js	
@@ -35,38 +35,47 @@ Errors::
 
 3     "sourcemap": true,
       ~~~~~~~~~~~
+
 tsconfig.json:4:5 - error TS5025: Unknown compiler option 'declarationmap'. Did you mean 'declarationMap'?
 
 4     "declarationmap": true,
       ~~~~~~~~~~~~~~~~
+
 tsconfig.json:5:5 - error TS5025: Unknown compiler option 'nouncheckedindexedaccess'. Did you mean 'noUncheckedIndexedAccess'?
 
 5     "nouncheckedindexedaccess": true,
       ~~~~~~~~~~~~~~~~~~~~~~~~~~
+
 tsconfig.json:6:5 - error TS5025: Unknown compiler option 'exactoptionalpropertytypes'. Did you mean 'exactOptionalPropertyTypes'?
 
 6     "exactoptionalpropertytypes": true,
       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
 tsconfig.json:7:5 - error TS5025: Unknown compiler option 'verbatimmodulesyntax'. Did you mean 'verbatimModuleSyntax'?
 
 7     "verbatimmodulesyntax": true,
       ~~~~~~~~~~~~~~~~~~~~~~
+
 tsconfig.json:8:5 - error TS5025: Unknown compiler option 'isolatedmodules'. Did you mean 'isolatedModules'?
 
 8     "isolatedmodules": true,
       ~~~~~~~~~~~~~~~~~
+
 tsconfig.json:9:5 - error TS5025: Unknown compiler option 'nouncheckedsideeffectimports'. Did you mean 'noUncheckedSideEffectImports'?
 
 9     "nouncheckedsideeffectimports": true,
       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
 tsconfig.json:10:5 - error TS5025: Unknown compiler option 'moduledetection'. Did you mean 'moduleDetection'?
 
 10     "moduledetection": "force",
        ~~~~~~~~~~~~~~~~~
+
 tsconfig.json:11:5 - error TS5025: Unknown compiler option 'skiplibcheck'. Did you mean 'skipLibCheck'?
 
 11     "skiplibcheck": true,
        ~~~~~~~~~~~~~~
+
 tsconfig.json:12:5 - error TS5025: Unknown compiler option 'checkjs'. Did you mean 'checkJs'?
 
 12     "checkjs": true
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with json api.js
index f51e477c660e1..9ad898f4d6399 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with json api.js	
@@ -18,5 +18,4 @@ FileNames::
 Errors::
 error TS6046: Argument for '--target' option must be: 'es6', 'es2015', 'es2016', 'es2017', 'es2018', 'es2019', 'es2020', 'es2021', 'es2022', 'es2023', 'es2024', 'es2025', 'esnext'.
 error TS5024: Compiler option 'removeComments' requires a value of type boolean.
-error TS6046: Argument for '--moduleResolution' option must be: 'node16', 'nodenext', 'bundler'.
-
+error TS6046: Argument for '--moduleResolution' option must be: 'node16', 'nodenext', 'bundler'.
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with jsonSourceFile api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with jsonSourceFile api.js
index 422e4c3c9f352..a32648be78659 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with jsonSourceFile api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports errors for wrong type option and invalid enum value with jsonSourceFile api.js	
@@ -20,10 +20,12 @@ Errors::
 
 3     "target": "invalid value",
                 ~~~~~~~~~~~~~~~
+
 tsconfig.json:4:23 - error TS5024: Compiler option 'removeComments' requires a value of type boolean.
 
 4     "removeComments": "should be a boolean",
                         ~~~~~~~~~~~~~~~~~~~~~
+
 tsconfig.json:5:25 - error TS6046: Argument for '--moduleResolution' option must be: 'node16', 'nodenext', 'bundler'.
 
 5     "moduleResolution": "invalid value"
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with json api.js
index a5d32b708c15d..b79c50099efe3 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/reports spelling suggestion for an unknown option with json api.js	
@@ -14,5 +14,4 @@ configFileName:: tsconfig.json
 FileNames::
 /app.ts
 Errors::
-error TS5025: Unknown compiler option 'targt'. Did you mean 'target'?
-
+error TS5025: Unknown compiler option 'targt'. Did you mean 'target'?
diff --git a/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with json api.js b/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with json api.js
index eb0f0e1d547cb..f1ec52ed93f99 100644
--- a/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with json api.js	
+++ b/tsc/testdata/baselines/reference/config/tsconfigParsing/returns error when tsconfig have excludes with json api.js	
@@ -20,5 +20,4 @@ configFileName:: tsconfig.json
 FileNames::
 /apath/foge.ts,/apath/test.ts
 Errors::
-error TS6114: Unknown option 'excludes'. Did you mean 'exclude'?
-
+error TS6114: Unknown option 'excludes'. Did you mean 'exclude'?
diff --git a/tsc/testdata/baselines/reference/conformance/typedefCrossModule5.errors.txt b/tsc/testdata/baselines/reference/conformance/typedefCrossModule5.errors.txt
index d557f9ab1eb76..748c5510b8d78 100644
--- a/tsc/testdata/baselines/reference/conformance/typedefCrossModule5.errors.txt
+++ b/tsc/testdata/baselines/reference/conformance/typedefCrossModule5.errors.txt
@@ -3,37 +3,36 @@
 1 /** @typedef {number} Foo */
                         ~~~
 
-  mod2.js:1:7
+  mod2.js:1:7 - 'Foo' was also declared here.
     1 class Foo { } // should error
             ~~~
-    'Foo' was also declared here.
+
 mod1.js:2:7 - error TS2451: Cannot redeclare block-scoped variable 'Bar'.
 
 2 class Bar {}
         ~~~
 
-  mod2.js:2:7
+  mod2.js:2:7 - 'Bar' was also declared here.
     2 const Bar = 3;
             ~~~
-    'Bar' was also declared here.
+
 mod2.js:1:7 - error TS2300: Duplicate identifier 'Foo'.
 
 1 class Foo { } // should error
         ~~~
 
-  mod1.js:1:23
+  mod1.js:1:23 - 'Foo' was also declared here.
     1 /** @typedef {number} Foo */
                             ~~~
-    'Foo' was also declared here.
+
 mod2.js:2:7 - error TS2451: Cannot redeclare block-scoped variable 'Bar'.
 
 2 const Bar = 3;
         ~~~
 
-  mod1.js:2:7
+  mod1.js:2:7 - 'Bar' was also declared here.
     2 class Bar {}
             ~~~
-    'Bar' was also declared here.
 
 
 ==== mod1.js (2 errors) ====
diff --git a/tsc/testdata/baselines/reference/tsbuild/commandLine/bad-locale.js b/tsc/testdata/baselines/reference/tsbuild/commandLine/bad-locale.js
index 41ce42d0822cf..f85b09a8f91b0 100644
--- a/tsc/testdata/baselines/reference/tsbuild/commandLine/bad-locale.js
+++ b/tsc/testdata/baselines/reference/tsbuild/commandLine/bad-locale.js
@@ -7,4 +7,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS6048: Locale must be an IETF BCP 47 language tag. Examples: 'en', 'ja-jp'.
 
-
diff --git a/tsc/testdata/baselines/reference/tsbuild/commandLine/when-build-not-first-argument.js b/tsc/testdata/baselines/reference/tsbuild/commandLine/when-build-not-first-argument.js
index 1b6af49f54f0d..d44964311b2eb 100644
--- a/tsc/testdata/baselines/reference/tsbuild/commandLine/when-build-not-first-argument.js
+++ b/tsc/testdata/baselines/reference/tsbuild/commandLine/when-build-not-first-argument.js
@@ -6,7 +6,5 @@ tsgo --verbose --build
 ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5093: Compiler option '--verbose' may only be used with '--build'.
-
 error TS6369: Option '--build' must be the first command line argument.
 
-
diff --git a/tsc/testdata/baselines/reference/tsbuild/configFileErrors/missing-config-file.js b/tsc/testdata/baselines/reference/tsbuild/configFileErrors/missing-config-file.js
index 8d1d180950b1c..c194821e7e3a0 100644
--- a/tsc/testdata/baselines/reference/tsbuild/configFileErrors/missing-config-file.js
+++ b/tsc/testdata/baselines/reference/tsbuild/configFileErrors/missing-config-file.js
@@ -7,7 +7,6 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS6053: File '/home/src/workspaces/project/bogus.json' not found.
 
-
 Found 1 error.
 
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/configFileErrors/when-tsconfig-extends-the-missing-file.js b/tsc/testdata/baselines/reference/tsbuild/configFileErrors/when-tsconfig-extends-the-missing-file.js
index 83ba10640a7b8..04120bd116f8a 100644
--- a/tsc/testdata/baselines/reference/tsbuild/configFileErrors/when-tsconfig-extends-the-missing-file.js
+++ b/tsc/testdata/baselines/reference/tsbuild/configFileErrors/when-tsconfig-extends-the-missing-file.js
@@ -30,14 +30,10 @@ tsgo --b
 ExitStatus:: DiagnosticsPresent_OutputsGenerated
 Output::
 error TS5083: Cannot read file '/home/src/workspaces/project/foobar.json'.
-
 error TS18003: No inputs were found in config file '/home/src/workspaces/project/tsconfig.first.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
-
 error TS5083: Cannot read file '/home/src/workspaces/project/foobar.json'.
-
 error TS18003: No inputs were found in config file '/home/src/workspaces/project/tsconfig.second.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
 
-
 Found 4 errors.
 
 //// [/home/src/workspaces/project/tsconfig.first.tsbuildinfo] *new* 
diff --git a/tsc/testdata/baselines/reference/tsbuild/demo/in-circular-branch-reports-the-error-about-it-by-stopping-build.js b/tsc/testdata/baselines/reference/tsbuild/demo/in-circular-branch-reports-the-error-about-it-by-stopping-build.js
index bcc735c0c26b2..6753102212018 100644
--- a/tsc/testdata/baselines/reference/tsbuild/demo/in-circular-branch-reports-the-error-about-it-by-stopping-build.js
+++ b/tsc/testdata/baselines/reference/tsbuild/demo/in-circular-branch-reports-the-error-about-it-by-stopping-build.js
@@ -128,7 +128,6 @@ Output::
 /user/username/projects/demo/zoo/tsconfig.json
 /user/username/projects/demo/animals/tsconfig.json
 
-
 Found 1 error.
 
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/noCheck/dts-errors-with-incremental.js b/tsc/testdata/baselines/reference/tsbuild/noCheck/dts-errors-with-incremental.js
index 7317ea74d8899..bbb460196c3bb 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noCheck/dts-errors-with-incremental.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noCheck/dts-errors-with-incremental.js
@@ -28,10 +28,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -190,10 +189,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -448,10 +446,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -582,10 +579,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -614,10 +610,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -1045,10 +1040,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsbuild/noCheck/dts-errors.js b/tsc/testdata/baselines/reference/tsbuild/noCheck/dts-errors.js
index be71f7f25d0e0..a1c925662626e 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noCheck/dts-errors.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noCheck/dts-errors.js
@@ -28,10 +28,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Updating unchanged output timestamps of project 'tsconfig.json'...
 
@@ -121,10 +120,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Updating unchanged output timestamps of project 'tsconfig.json'...
 
@@ -302,10 +300,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Updating unchanged output timestamps of project 'tsconfig.json'...
 
@@ -369,10 +366,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Updating unchanged output timestamps of project 'tsconfig.json'...
 
@@ -411,10 +407,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Updating unchanged output timestamps of project 'tsconfig.json'...
 
@@ -642,10 +637,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Updating unchanged output timestamps of project 'tsconfig.json'...
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-composite.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-composite.js
index 2a5ed7dde09e7..5e30488659633 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-composite.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-composite.js
@@ -365,20 +365,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -982,20 +980,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1266,20 +1262,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1317,20 +1311,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1368,20 +1360,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1419,20 +1409,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-incremental-declaration.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-incremental-declaration.js
index d9ca79fa2b2a7..edc7612baca6a 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-incremental-declaration.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-incremental-declaration.js
@@ -364,20 +364,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -957,20 +955,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1243,20 +1239,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1294,20 +1288,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1345,20 +1337,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1396,20 +1386,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-incremental.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-incremental.js
index d8b3a3979c423..44116bd52c4a7 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-incremental.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-incremental.js
@@ -306,20 +306,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -875,20 +873,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1134,20 +1130,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1185,20 +1179,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1236,20 +1228,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1287,20 +1277,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-composite.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-composite.js
index 5b4df4b9c1042..90722985262a1 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-composite.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-composite.js
@@ -524,20 +524,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-incremental-declaration.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-incremental-declaration.js
index 2ce86dff240ed..2ee26d6b550a1 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-incremental-declaration.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-incremental-declaration.js
@@ -497,20 +497,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-incremental.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-incremental.js
index c3d8097f3cb78..ebf7151afa8a1 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-incremental.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-incremental.js
@@ -436,20 +436,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-incremental-as-modules.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-incremental-as-modules.js
index e937dbec56714..f3f845431f1d5 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-incremental-as-modules.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-incremental-as-modules.js
@@ -146,10 +146,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -277,10 +276,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -422,10 +420,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-incremental.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-incremental.js
index 490e73f31cccf..d104050739f79 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-incremental.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-incremental.js
@@ -133,10 +133,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -251,10 +250,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -383,10 +381,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-multiple-files.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-multiple-files.js
index 5ccc29291276d..b4897da99ae1f 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-multiple-files.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes-with-multiple-files.js
@@ -178,30 +178,27 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 c.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14
+  c.ts:1:14 - Add a type annotation to the variable c.
     1 export const c = class { private p = 10; };
                    ~
-    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14
+  d.ts:1:14 - Add a type annotation to the variable d.
     1 export const d = class { private p = 10; };
                    ~
-    Add a type annotation to the variable d.
 
 
 Found 3 errors in 3 files.
@@ -420,30 +417,27 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 c.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14
+  c.ts:1:14 - Add a type annotation to the variable c.
     1 export const c = class { private p = 10; };
                    ~
-    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14
+  d.ts:1:14 - Add a type annotation to the variable d.
     1 export const d = class { private p = 10; };
                    ~
-    Add a type annotation to the variable d.
 
 
 Found 3 errors in 3 files.
@@ -676,30 +670,27 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 c.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14
+  c.ts:1:14 - Add a type annotation to the variable c.
     1 export const c = class { private p = 10; };
                    ~
-    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14
+  d.ts:1:14 - Add a type annotation to the variable d.
     1 export const d = class { private p = 10; };
                    ~
-    Add a type annotation to the variable d.
 
 
 Found 3 errors in 3 files.
@@ -1072,20 +1063,18 @@ Output::
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14
+  c.ts:1:14 - Add a type annotation to the variable c.
     1 export const c = class { private p = 10; };
                    ~
-    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14
+  d.ts:1:14 - Add a type annotation to the variable d.
     1 export const d = class { private p = 10; };
                    ~
-    Add a type annotation to the variable d.
 
 
 Found 2 errors in 2 files.
@@ -1286,20 +1275,18 @@ Output::
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14
+  c.ts:1:14 - Add a type annotation to the variable c.
     1 export const c = class { private p = 10; };
                    ~
-    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14
+  d.ts:1:14 - Add a type annotation to the variable d.
     1 export const d = class { private p = 10; };
                    ~
-    Add a type annotation to the variable d.
 
 
 Found 2 errors in 2 files.
@@ -1503,10 +1490,9 @@ Output::
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14
+  d.ts:1:14 - Add a type annotation to the variable d.
     1 export const d = class { private p = 10; };
                    ~
-    Add a type annotation to the variable d.
 
 
 Found 1 error in d.ts:1
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes.js
index bd48227f7755d..58527768b2b86 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-declaration-enable-changes.js
@@ -105,10 +105,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -154,10 +153,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -224,10 +222,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Updating unchanged output timestamps of project 'tsconfig.json'...
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-incremental-as-modules.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-incremental-as-modules.js
index 72f5632b7fcf2..dd20817117c4a 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-incremental-as-modules.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-incremental-as-modules.js
@@ -28,10 +28,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -185,10 +184,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -436,10 +434,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -584,10 +581,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -717,10 +713,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-incremental.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-incremental.js
index d9506c4bd6a3f..c719ef150f4d8 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-incremental.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors-with-incremental.js
@@ -26,10 +26,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -169,10 +168,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -384,10 +382,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -506,10 +503,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -621,10 +617,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors.js b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors.js
index d2addd198b59f..6ea5a365d78c4 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmit/dts-errors.js
@@ -26,10 +26,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -98,10 +97,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -236,10 +234,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -285,10 +282,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Updating unchanged output timestamps of project 'tsconfig.json'...
 
@@ -329,10 +325,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmitOnError/dts-errors-with-declaration-with-incremental.js b/tsc/testdata/baselines/reference/tsbuild/noEmitOnError/dts-errors-with-declaration-with-incremental.js
index e3e9765a8d774..80bca24844738 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmitOnError/dts-errors-with-declaration-with-incremental.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmitOnError/dts-errors-with-declaration-with-incremental.js
@@ -36,10 +36,9 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14
+  src/main.ts:2:14 - Add a type annotation to the variable a.
     2 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in src/main.ts:2
@@ -222,10 +221,9 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14
+  src/main.ts:2:14 - Add a type annotation to the variable a.
     2 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in src/main.ts:2
diff --git a/tsc/testdata/baselines/reference/tsbuild/noEmitOnError/dts-errors-with-declaration.js b/tsc/testdata/baselines/reference/tsbuild/noEmitOnError/dts-errors-with-declaration.js
index 8615949e8e748..1c5fe2ab6db76 100644
--- a/tsc/testdata/baselines/reference/tsbuild/noEmitOnError/dts-errors-with-declaration.js
+++ b/tsc/testdata/baselines/reference/tsbuild/noEmitOnError/dts-errors-with-declaration.js
@@ -36,10 +36,9 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14
+  src/main.ts:2:14 - Add a type annotation to the variable a.
     2 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in src/main.ts:2
@@ -122,10 +121,9 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14
+  src/main.ts:2:14 - Add a type annotation to the variable a.
     2 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in src/main.ts:2
diff --git a/tsc/testdata/baselines/reference/tsbuild/outputPaths/when-rootDir-is-specified-but-not-all-files-belong-to-rootDir-and-is-composite.js b/tsc/testdata/baselines/reference/tsbuild/outputPaths/when-rootDir-is-specified-but-not-all-files-belong-to-rootDir-and-is-composite.js
index 2ae7a6dece635..64dfdb89976d2 100644
--- a/tsc/testdata/baselines/reference/tsbuild/outputPaths/when-rootDir-is-specified-but-not-all-files-belong-to-rootDir-and-is-composite.js
+++ b/tsc/testdata/baselines/reference/tsbuild/outputPaths/when-rootDir-is-specified-but-not-all-files-belong-to-rootDir-and-is-composite.js
@@ -28,7 +28,6 @@ Output::
   The file is in the program because:
     Matched by default include pattern '**/*'
 
-
 Found 1 error.
 
 //// [/home/src/tslibs/TS/Lib/lib.es2025.full.d.ts] *Lib*
@@ -165,7 +164,6 @@ Output::
   The file is in the program because:
     Matched by default include pattern '**/*'
 
-
 Found 1 error.
 
 
@@ -186,7 +184,6 @@ Output::
   The file is in the program because:
     Matched by default include pattern '**/*'
 
-
 Found 1 error.
 
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/outputPaths/when-rootDir-is-specified-but-not-all-files-belong-to-rootDir.js b/tsc/testdata/baselines/reference/tsbuild/outputPaths/when-rootDir-is-specified-but-not-all-files-belong-to-rootDir.js
index fb88da9a58094..ef89e37d1413c 100644
--- a/tsc/testdata/baselines/reference/tsbuild/outputPaths/when-rootDir-is-specified-but-not-all-files-belong-to-rootDir.js
+++ b/tsc/testdata/baselines/reference/tsbuild/outputPaths/when-rootDir-is-specified-but-not-all-files-belong-to-rootDir.js
@@ -27,7 +27,6 @@ Output::
   The file is in the program because:
     Matched by default include pattern '**/*'
 
-
 Found 1 error.
 
 //// [/home/src/tslibs/TS/Lib/lib.es2025.full.d.ts] *Lib*
@@ -106,7 +105,6 @@ Output::
   The file is in the program because:
     Matched by default include pattern '**/*'
 
-
 Found 1 error.
 
 //// [/home/src/workspaces/project/dist/index.js] *rewrite with same content*
@@ -131,7 +129,6 @@ Output::
   The file is in the program because:
     Matched by default include pattern '**/*'
 
-
 Found 1 error.
 
 //// [/home/src/workspaces/project/dist/index.js] *rewrite with same content*
diff --git a/tsc/testdata/baselines/reference/tsbuild/resolveJsonModule/importing-json-module-from-project-reference.js b/tsc/testdata/baselines/reference/tsbuild/resolveJsonModule/importing-json-module-from-project-reference.js
index fe10e5b98a911..91ded68a14bbe 100644
--- a/tsc/testdata/baselines/reference/tsbuild/resolveJsonModule/importing-json-module-from-project-reference.js
+++ b/tsc/testdata/baselines/reference/tsbuild/resolveJsonModule/importing-json-module-from-project-reference.js
@@ -55,7 +55,6 @@ Output::
 [HH:MM:SS AM] Building project 'project/strings/tsconfig.json'...
 
 error TS5108: Option 'target=ES5' has been removed. Please remove it from your configuration.
-
 ../../tslibs/TS/Lib/lib.d.ts
    Default library for target 'ES5'
 project/strings/foo.json
@@ -65,7 +64,6 @@ project/strings/foo.json
 [HH:MM:SS AM] Building project 'project/main/tsconfig.json'...
 
 error TS5108: Option 'target=ES5' has been removed. Please remove it from your configuration.
-
 ../../tslibs/TS/Lib/lib.d.ts
    Default library for target 'ES5'
 project/strings/foo.json
@@ -272,7 +270,6 @@ Output::
 [HH:MM:SS AM] Building project 'project/strings/tsconfig.json'...
 
 error TS5108: Option 'target=ES5' has been removed. Please remove it from your configuration.
-
 ../../tslibs/TS/Lib/lib.d.ts
    Default library for target 'ES5'
 project/strings/foo.json
@@ -282,7 +279,6 @@ project/strings/foo.json
 [HH:MM:SS AM] Building project 'project/main/tsconfig.json'...
 
 error TS5108: Option 'target=ES5' has been removed. Please remove it from your configuration.
-
 ../../tslibs/TS/Lib/lib.d.ts
    Default library for target 'ES5'
 project/strings/foo.json
diff --git a/tsc/testdata/baselines/reference/tsbuild/sample/building-project-in-not-build-order-doesnt-throw-error.js b/tsc/testdata/baselines/reference/tsbuild/sample/building-project-in-not-build-order-doesnt-throw-error.js
index 89bf911460ba4..bda501271aebb 100644
--- a/tsc/testdata/baselines/reference/tsbuild/sample/building-project-in-not-build-order-doesnt-throw-error.js
+++ b/tsc/testdata/baselines/reference/tsbuild/sample/building-project-in-not-build-order-doesnt-throw-error.js
@@ -70,7 +70,6 @@ Output::
 
 error TS6053: File '/user/username/projects/sample1/logic2/tsconfig.json' not found.
 
-
 Found 1 error.
 
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/sample/cleaning-project-in-not-build-order-doesnt-throw-error.js b/tsc/testdata/baselines/reference/tsbuild/sample/cleaning-project-in-not-build-order-doesnt-throw-error.js
index cd0e6fb6b413b..5a1bbd8d55785 100644
--- a/tsc/testdata/baselines/reference/tsbuild/sample/cleaning-project-in-not-build-order-doesnt-throw-error.js
+++ b/tsc/testdata/baselines/reference/tsbuild/sample/cleaning-project-in-not-build-order-doesnt-throw-error.js
@@ -65,7 +65,6 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS6053: File '/user/username/projects/sample1/logic2/tsconfig.json' not found.
 
-
 Found 1 error.
 
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/sample/reports-error-if-input-file-is-missing-with-force.js b/tsc/testdata/baselines/reference/tsbuild/sample/reports-error-if-input-file-is-missing-with-force.js
index 14cdedc21f3a1..aca525d206f64 100644
--- a/tsc/testdata/baselines/reference/tsbuild/sample/reports-error-if-input-file-is-missing-with-force.js
+++ b/tsc/testdata/baselines/reference/tsbuild/sample/reports-error-if-input-file-is-missing-with-force.js
@@ -69,11 +69,9 @@ Output::
 error TS6053: File '/user/username/projects/sample1/core/anotherModule.ts' not found.
   The file is in the program because:
     Part of 'files' list in tsconfig.json
-
-  core/tsconfig.json:3:16
+  core/tsconfig.json:3:16 - File is matched by 'files' list specified here.
     3      "files": ["anotherModule.ts", "index.ts", "some_decl.d.ts"],
                      ~~~~~~~~~~~~~~~~~~
-    File is matched by 'files' list specified here.
 
 [HH:MM:SS AM] Project 'logic/tsconfig.json' is being forcibly rebuilt
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/sample/reports-error-if-input-file-is-missing.js b/tsc/testdata/baselines/reference/tsbuild/sample/reports-error-if-input-file-is-missing.js
index 81f11be9100b8..48909bacf674f 100644
--- a/tsc/testdata/baselines/reference/tsbuild/sample/reports-error-if-input-file-is-missing.js
+++ b/tsc/testdata/baselines/reference/tsbuild/sample/reports-error-if-input-file-is-missing.js
@@ -69,11 +69,9 @@ Output::
 error TS6053: File '/user/username/projects/sample1/core/anotherModule.ts' not found.
   The file is in the program because:
     Part of 'files' list in tsconfig.json
-
-  core/tsconfig.json:3:16
+  core/tsconfig.json:3:16 - File is matched by 'files' list specified here.
     3      "files": ["anotherModule.ts", "index.ts", "some_decl.d.ts"],
                      ~~~~~~~~~~~~~~~~~~
-    File is matched by 'files' list specified here.
 
 [HH:MM:SS AM] Project 'logic/tsconfig.json' is out of date because output file 'logic/tsconfig.tsbuildinfo' does not exist
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors-when-test-does-not-reference-core.js b/tsc/testdata/baselines/reference/tsbuild/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors-when-test-does-not-reference-core.js
index 5a9d28fca3d8d..3ea7785e80104 100644
--- a/tsc/testdata/baselines/reference/tsbuild/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors-when-test-does-not-reference-core.js
+++ b/tsc/testdata/baselines/reference/tsbuild/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors-when-test-does-not-reference-core.js
@@ -76,10 +76,9 @@ Output::
 3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                                                   ~~~~~~~~
 
-  core/index.ts:3:26
+  core/index.ts:3:26 - An argument for 'a' was not provided.
     3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                ~~~~~~~~~
-    An argument for 'a' was not provided.
 
 [HH:MM:SS AM] Project 'logic/tsconfig.json' can't be built because its dependency 'core' has errors
 
@@ -278,10 +277,9 @@ Output::
 3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                                                   ~~~~~~~~
 
-  core/index.ts:3:26
+  core/index.ts:3:26 - An argument for 'a' was not provided.
     3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                ~~~~~~~~~
-    An argument for 'a' was not provided.
 
 [HH:MM:SS AM] Project 'logic/tsconfig.json' can't be built because its dependency 'core' has errors
 
diff --git a/tsc/testdata/baselines/reference/tsbuild/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors.js b/tsc/testdata/baselines/reference/tsbuild/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors.js
index 83989c3f96c1c..f8439919cb630 100644
--- a/tsc/testdata/baselines/reference/tsbuild/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors.js
+++ b/tsc/testdata/baselines/reference/tsbuild/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors.js
@@ -77,10 +77,9 @@ Output::
 3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                                                   ~~~~~~~~
 
-  core/index.ts:3:26
+  core/index.ts:3:26 - An argument for 'a' was not provided.
     3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                ~~~~~~~~~
-    An argument for 'a' was not provided.
 
 [HH:MM:SS AM] Project 'logic/tsconfig.json' can't be built because its dependency 'core' has errors
 
@@ -279,10 +278,9 @@ Output::
 3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                                                   ~~~~~~~~
 
-  core/index.ts:3:26
+  core/index.ts:3:26 - An argument for 'a' was not provided.
     3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                ~~~~~~~~~
-    An argument for 'a' was not provided.
 
 [HH:MM:SS AM] Project 'logic/tsconfig.json' can't be built because its dependency 'core' has errors
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/demo/updates-with-circular-reference.js b/tsc/testdata/baselines/reference/tsbuildWatch/demo/updates-with-circular-reference.js
index f05ffcbbf76a3..0ff2c58725af6 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/demo/updates-with-circular-reference.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/demo/updates-with-circular-reference.js
@@ -129,7 +129,6 @@ Output::
 /user/username/projects/demo/core/tsconfig.json
 /user/username/projects/demo/zoo/tsconfig.json
 /user/username/projects/demo/animals/tsconfig.json
-
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors-with-incremental-as-modules.js b/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors-with-incremental-as-modules.js
index c020d1d30f47e..265f254afb9fe 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors-with-incremental-as-modules.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors-with-incremental-as-modules.js
@@ -30,10 +30,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -441,10 +440,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -600,10 +598,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -744,10 +741,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors-with-incremental.js b/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors-with-incremental.js
index 039461c4ad11d..5f8d8bba4132d 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors-with-incremental.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors-with-incremental.js
@@ -28,10 +28,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -389,10 +388,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -522,10 +520,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -648,10 +645,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors.js b/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors.js
index fc71aa91ec852..78428c9996a7f 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/noEmit/dts-errors.js
@@ -28,10 +28,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -225,10 +224,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -284,10 +282,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Updating unchanged output timestamps of project 'tsconfig.json'...
 
@@ -338,10 +335,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/noEmitOnError/noEmitOnError-with-declaration-with-incremental.js b/tsc/testdata/baselines/reference/tsbuildWatch/noEmitOnError/noEmitOnError-with-declaration-with-incremental.js
index 9c69b168009c3..167a5b6ded6e4 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/noEmitOnError/noEmitOnError-with-declaration-with-incremental.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/noEmitOnError/noEmitOnError-with-declaration-with-incremental.js
@@ -731,10 +731,9 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14
+  src/main.ts:2:14 - Add a type annotation to the variable a.
     2 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -896,10 +895,9 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14
+  src/main.ts:2:14 - Add a type annotation to the variable a.
     2 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/noEmitOnError/noEmitOnError-with-declaration.js b/tsc/testdata/baselines/reference/tsbuildWatch/noEmitOnError/noEmitOnError-with-declaration.js
index 0071c86b73b50..430db82e70af3 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/noEmitOnError/noEmitOnError-with-declaration.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/noEmitOnError/noEmitOnError-with-declaration.js
@@ -488,10 +488,9 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14
+  src/main.ts:2:14 - Add a type annotation to the variable a.
     2 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -555,10 +554,9 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14
+  src/main.ts:2:14 - Add a type annotation to the variable a.
     2 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-introduceError-when-file-with-no-error-changes.js b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-introduceError-when-file-with-no-error-changes.js
index 2398fd6998e06..c29ff1a88a093 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-introduceError-when-file-with-no-error-changes.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-introduceError-when-file-with-no-error-changes.js
@@ -161,10 +161,9 @@ Output::
 1 export var myClassWithError = class {
              ~~~~~~~~~~~~~~~~
 
-  app/fileWithError.ts:1:12
+  app/fileWithError.ts:1:12 - Add a type annotation to the variable myClassWithError.
     1 export var myClassWithError = class {
                  ~~~~~~~~~~~~~~~~
-    Add a type annotation to the variable myClassWithError.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -303,10 +302,9 @@ Output::
 1 export var myClassWithError = class {
              ~~~~~~~~~~~~~~~~
 
-  app/fileWithError.ts:1:12
+  app/fileWithError.ts:1:12 - Add a type annotation to the variable myClassWithError.
     1 export var myClassWithError = class {
                  ~~~~~~~~~~~~~~~~
-    Add a type annotation to the variable myClassWithError.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-introduceError-when-fixing-errors-only-changed-file-is-emitted.js b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-introduceError-when-fixing-errors-only-changed-file-is-emitted.js
index f8fb35d19a78b..27e5d2018aeb8 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-introduceError-when-fixing-errors-only-changed-file-is-emitted.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-introduceError-when-fixing-errors-only-changed-file-is-emitted.js
@@ -161,10 +161,9 @@ Output::
 1 export var myClassWithError = class {
              ~~~~~~~~~~~~~~~~
 
-  app/fileWithError.ts:1:12
+  app/fileWithError.ts:1:12 - Add a type annotation to the variable myClassWithError.
     1 export var myClassWithError = class {
                  ~~~~~~~~~~~~~~~~
-    Add a type annotation to the variable myClassWithError.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-when-file-with-no-error-changes.js b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-when-file-with-no-error-changes.js
index b19de72392db6..7d854c571330c 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-when-file-with-no-error-changes.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-when-file-with-no-error-changes.js
@@ -25,10 +25,9 @@ Output::
 1 export var myClassWithError = class {
              ~~~~~~~~~~~~~~~~
 
-  app/fileWithError.ts:1:12
+  app/fileWithError.ts:1:12 - Add a type annotation to the variable myClassWithError.
     1 export var myClassWithError = class {
                  ~~~~~~~~~~~~~~~~
-    Add a type annotation to the variable myClassWithError.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
@@ -191,10 +190,9 @@ Output::
 1 export var myClassWithError = class {
              ~~~~~~~~~~~~~~~~
 
-  app/fileWithError.ts:1:12
+  app/fileWithError.ts:1:12 - Add a type annotation to the variable myClassWithError.
     1 export var myClassWithError = class {
                  ~~~~~~~~~~~~~~~~
-    Add a type annotation to the variable myClassWithError.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-when-fixing-error-files-all-files-are-emitted.js b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-when-fixing-error-files-all-files-are-emitted.js
index d314748adb740..d99e8d2345cda 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-when-fixing-error-files-all-files-are-emitted.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/declarationEmitErrors-when-fixing-error-files-all-files-are-emitted.js
@@ -25,10 +25,9 @@ Output::
 1 export var myClassWithError = class {
              ~~~~~~~~~~~~~~~~
 
-  app/fileWithError.ts:1:12
+  app/fileWithError.ts:1:12 - Add a type annotation to the variable myClassWithError.
     1 export var myClassWithError = class {
                  ~~~~~~~~~~~~~~~~
-    Add a type annotation to the variable myClassWithError.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/when-referenced-project-change-introduces-error-in-the-down-stream-project-and-then-fixes-it.js b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/when-referenced-project-change-introduces-error-in-the-down-stream-project-and-then-fixes-it.js
index d53e0620d4ed5..cfba79d6835b6 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/when-referenced-project-change-introduces-error-in-the-down-stream-project-and-then-fixes-it.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/when-referenced-project-change-introduces-error-in-the-down-stream-project-and-then-fixes-it.js
@@ -183,10 +183,9 @@ Output::
 2 createSomeObject().message;
                      ~~~~~~~
 
-  Library/library.d.ts:2:5
+  Library/library.d.ts:2:5 - 'message2' is declared here.
     2     message2: string;
           ~~~~~~~~
-    'message2' is declared here.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js
index ae50819dd158f..9d62bab02b1b0 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js
@@ -611,7 +611,6 @@ Output::
 [HH:MM:SS AM] Project 'project3.tsconfig.json' is up to date because newest input 'other2.ts' is older than output 'project3.tsconfig.tsbuildinfo'
 
 error TS5083: Cannot read file '/user/username/projects/project/extendsConfig2.tsconfig.json'.
-
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/reexport/Reports-errors-correctly.js b/tsc/testdata/baselines/reference/tsbuildWatch/reexport/Reports-errors-correctly.js
index 5fd9f7e1a78bd..e763e740bf64d 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/reexport/Reports-errors-correctly.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/reexport/Reports-errors-correctly.js
@@ -249,10 +249,9 @@ Output::
 3 export const session: Session = {
                ~~~~~~~
 
-  out/pure/session.d.ts:3:5
+  out/pure/session.d.ts:3:5 - 'bar' is declared here.
     3     bar: number;
           ~~~
-    'bar' is declared here.
 
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors-when-test-does-not-reference-core.js b/tsc/testdata/baselines/reference/tsbuildWatch/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors-when-test-does-not-reference-core.js
index 3f5f319baf05e..e428153fc5354 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors-when-test-does-not-reference-core.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors-when-test-does-not-reference-core.js
@@ -78,10 +78,9 @@ Output::
 3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                                                   ~~~~~~~~
 
-  core/index.ts:3:26
+  core/index.ts:3:26 - An argument for 'a' was not provided.
     3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                ~~~~~~~~~
-    An argument for 'a' was not provided.
 
 [HH:MM:SS AM] Project 'logic/tsconfig.json' can't be built because its dependency 'core' has errors
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors.js b/tsc/testdata/baselines/reference/tsbuildWatch/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors.js
index 26adb0086f507..24ee4890e7ad0 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/sample/skips-builds-downstream-projects-if-upstream-projects-have-errors-with-stopBuildOnErrors.js
@@ -79,10 +79,9 @@ Output::
 3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                                                   ~~~~~~~~
 
-  core/index.ts:3:26
+  core/index.ts:3:26 - An argument for 'a' was not provided.
     3 export function multiply(a: number, b: number) { return a * b; }multiply();
                                ~~~~~~~~~
-    An argument for 'a' was not provided.
 
 [HH:MM:SS AM] Project 'logic/tsconfig.json' can't be built because its dependency 'core' has errors
 
diff --git a/tsc/testdata/baselines/reference/tsbuildWatch/sample/watches-config-files-that-are-not-present.js b/tsc/testdata/baselines/reference/tsbuildWatch/sample/watches-config-files-that-are-not-present.js
index 8ab1914a6e512..f726961eaf767 100644
--- a/tsc/testdata/baselines/reference/tsbuildWatch/sample/watches-config-files-that-are-not-present.js
+++ b/tsc/testdata/baselines/reference/tsbuildWatch/sample/watches-config-files-that-are-not-present.js
@@ -54,7 +54,6 @@ Output::
 [HH:MM:SS AM] Starting compilation in watch mode...
 
 error TS6053: File '/user/username/projects/sample1/logic/tsconfig.json' not found.
-
 tests/tsconfig.json:4:9 - error TS6053: File '/user/username/projects/sample1/logic' not found.
 
 4         { "path": "../logic" },
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-incorrect-compiler-option-value.js b/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-incorrect-compiler-option-value.js
index e2a0f039d1534..a5717b385b1ad 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-incorrect-compiler-option-value.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-incorrect-compiler-option-value.js
@@ -7,4 +7,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS6046: Argument for '--lib' option must be: 'es5', 'es6', 'es2015', 'es7', 'es2016', 'es2017', 'es2018', 'es2019', 'es2020', 'es2021', 'es2022', 'es2023', 'es2024', 'es2025', 'esnext', 'dom', 'dom.iterable', 'dom.asynciterable', 'webworker', 'webworker.importscripts', 'webworker.iterable', 'webworker.asynciterable', 'scripthost', 'es2015.core', 'es2015.collection', 'es2015.generator', 'es2015.iterable', 'es2015.promise', 'es2015.proxy', 'es2015.reflect', 'es2015.symbol', 'es2015.symbol.wellknown', 'es2016.array.include', 'es2016.intl', 'es2017.arraybuffer', 'es2017.date', 'es2017.object', 'es2017.sharedmemory', 'es2017.string', 'es2017.intl', 'es2017.typedarrays', 'es2018.asyncgenerator', 'es2018.asynciterable', 'es2018.intl', 'es2018.promise', 'es2018.regexp', 'es2019.array', 'es2019.object', 'es2019.string', 'es2019.symbol', 'es2019.intl', 'es2020.bigint', 'es2020.date', 'es2020.promise', 'es2020.sharedmemory', 'es2020.string', 'es2020.symbol.wellknown', 'es2020.intl', 'es2020.number', 'es2021.promise', 'es2021.string', 'es2021.weakref', 'es2021.intl', 'es2022.array', 'es2022.error', 'es2022.intl', 'es2022.object', 'es2022.string', 'es2022.regexp', 'es2023.array', 'es2023.collection', 'es2023.intl', 'es2024.arraybuffer', 'es2024.collection', 'es2024.object', 'es2024.promise', 'es2024.regexp', 'es2024.sharedmemory', 'es2024.string', 'es2025.collection', 'es2025.float16', 'es2025.intl', 'es2025.iterator', 'es2025.promise', 'es2025.regexp', 'esnext.asynciterable', 'esnext.symbol', 'esnext.bigint', 'esnext.weakref', 'esnext.object', 'esnext.regexp', 'esnext.string', 'esnext.float16', 'esnext.iterator', 'esnext.promise', 'esnext.array', 'esnext.collection', 'esnext.date', 'esnext.decorators', 'esnext.disposable', 'esnext.error', 'esnext.intl', 'esnext.sharedmemory', 'esnext.temporal', 'esnext.typedarrays', 'decorators', 'decorators.legacy'.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-incorrect-compiler-option.js b/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-incorrect-compiler-option.js
index ab4cf00b46ddc..c31779e874f48 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-incorrect-compiler-option.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-incorrect-compiler-option.js
@@ -7,4 +7,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5023: Unknown compiler option '--someNonExistOption'.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-tsconfig.json.js b/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-tsconfig.json.js
index c422ba28acf9a..543a4d4988002 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-tsconfig.json.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/Initialized-TSConfig-with-tsconfig.json.js
@@ -16,4 +16,3 @@ ExitStatus:: Success
 Output::
 error TS5054: A 'tsconfig.json' file is already defined at: '/home/src/workspaces/project/tsconfig.json'.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/Parse-enum-type-options.js b/tsc/testdata/baselines/reference/tsc/commandLine/Parse-enum-type-options.js
index 4de743b46dda3..b717b2f59c748 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/Parse-enum-type-options.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/Parse-enum-type-options.js
@@ -9,7 +9,6 @@ Output::
   The file is in the program because:
     Root file specified for compilation
 
-
 Found 1 error.
 
 //// [/home/src/tslibs/TS/Lib/lib.esnext.full.d.ts] *Lib*
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/bad-locale.js b/tsc/testdata/baselines/reference/tsc/commandLine/bad-locale.js
index 1444c0edb4086..5d1ad434cd988 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/bad-locale.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/bad-locale.js
@@ -7,4 +7,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS6048: Locale must be an IETF BCP 47 language tag. Examples: 'en', 'ja-jp'.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-extended-tsconfig-in-different-folder-does-not-exist.js b/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-extended-tsconfig-in-different-folder-does-not-exist.js
index dca7ad9a8bbcc..117c61bb6b919 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-extended-tsconfig-in-different-folder-does-not-exist.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-extended-tsconfig-in-different-folder-does-not-exist.js
@@ -19,7 +19,6 @@ Output::
   The file is in the program because:
     Part of 'files' list in tsconfig.json
 
-
 Found 1 error.
 
 //// [/home/src/tslibs/TS/Lib/lib.es2025.full.d.ts] *Lib*
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-tsconfig-does-not-exist.js b/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-tsconfig-does-not-exist.js
index 9700068259c1f..df87dd1cf194d 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-tsconfig-does-not-exist.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-tsconfig-does-not-exist.js
@@ -12,11 +12,9 @@ Output::
 error TS6231: Could not resolve the path '/home/src/workspaces/project/src/doesNotExist' with the extensions: '.ts', '.tsx', '.d.ts', '.cts', '.d.cts', '.mts', '.d.mts'.
   The file is in the program because:
     Part of 'files' list in tsconfig.json
-
-  tsconfig.json:2:31
+  tsconfig.json:2:31 - File is matched by 'files' list specified here.
     2                     "files": ["./src/doesNotExist"]
                                     ~~~~~~~~~~~~~~~~~~~~
-    File is matched by 'files' list specified here.
 
 
 Found 1 error.
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-tsconfig-exists.js b/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-tsconfig-exists.js
index 4137c78adecd9..1bb69d8e84d93 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-tsconfig-exists.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-in-tsconfig-exists.js
@@ -14,11 +14,9 @@ Output::
 error TS6231: Could not resolve the path '/home/src/workspaces/project/src/script' with the extensions: '.ts', '.tsx', '.d.ts', '.cts', '.d.cts', '.mts', '.d.mts'.
   The file is in the program because:
     Part of 'files' list in tsconfig.json
-
-  tsconfig.json:2:31
+  tsconfig.json:2:31 - File is matched by 'files' list specified here.
     2                     "files": ["./src/script"]
                                     ~~~~~~~~~~~~~~
-    File is matched by 'files' list specified here.
 
 
 Found 1 error.
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-on-command-line-exists.js b/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-on-command-line-exists.js
index ae0eb00de4fc0..7689ac253590b 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-on-command-line-exists.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/extensionless-file-on-command-line-exists.js
@@ -11,7 +11,6 @@ Output::
   The file is in the program because:
     Root file specified for compilation
 
-
 Found 1 error.
 
 //// [/home/src/tslibs/TS/Lib/lib.es2025.full.d.ts] *Lib*
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/file-in-tsconfig-does-not-exist.js b/tsc/testdata/baselines/reference/tsc/commandLine/file-in-tsconfig-does-not-exist.js
index 0ae1d15323df1..c80648cdf5fc0 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/file-in-tsconfig-does-not-exist.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/file-in-tsconfig-does-not-exist.js
@@ -12,11 +12,9 @@ Output::
 error TS6053: File '/home/src/workspaces/project/src/doesNotExist.ts' not found.
   The file is in the program because:
     Part of 'files' list in tsconfig.json
-
-  tsconfig.json:2:31
+  tsconfig.json:2:31 - File is matched by 'files' list specified here.
     2                     "files": ["./src/doesNotExist.ts"]
                                     ~~~~~~~~~~~~~~~~~~~~~~~
-    File is matched by 'files' list specified here.
 
 
 Found 1 error.
diff --git a/tsc/testdata/baselines/reference/tsc/commandLine/non-object-config-root.js b/tsc/testdata/baselines/reference/tsc/commandLine/non-object-config-root.js
index 47c0e30593c69..c6d3698f57e9c 100644
--- a/tsc/testdata/baselines/reference/tsc/commandLine/non-object-config-root.js
+++ b/tsc/testdata/baselines/reference/tsc/commandLine/non-object-config-root.js
@@ -8,7 +8,6 @@ tsgo
 ExitStatus:: DiagnosticsPresent_OutputsGenerated
 Output::
 error TS18003: No inputs were found in config file '/home/src/workspaces/project/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
-
 tsconfig.json:1:1 - error TS5092: The root value of a 'tsconfig.json' file must be an object.
 
 1 []
diff --git a/tsc/testdata/baselines/reference/tsc/contentMapperFailures/initialization-failure-reports-one-project-error.js b/tsc/testdata/baselines/reference/tsc/contentMapperFailures/initialization-failure-reports-one-project-error.js
index 22c0e3d09a871..71ba40313f864 100644
--- a/tsc/testdata/baselines/reference/tsc/contentMapperFailures/initialization-failure-reports-one-project-error.js
+++ b/tsc/testdata/baselines/reference/tsc/contentMapperFailures/initialization-failure-reports-one-project-error.js
@@ -39,7 +39,6 @@ Output::
 error TS100057: The content mapper 'missing' could not be initialized.
   The content mapper command 'missing-mapper' could not be started: contentmappertest: unknown mapper command [missing-mapper]
 
-
 Found 1 error.
 
 //// [/home/src/tslibs/TS/Lib/lib.es2025.full.d.ts] *Lib*
diff --git a/tsc/testdata/baselines/reference/tsc/contentMapperFailures/mapper-is-disabled-after-repeated-failures.js b/tsc/testdata/baselines/reference/tsc/contentMapperFailures/mapper-is-disabled-after-repeated-failures.js
index ece8f82a664d3..9aed4ac03b683 100644
--- a/tsc/testdata/baselines/reference/tsc/contentMapperFailures/mapper-is-disabled-after-repeated-failures.js
+++ b/tsc/testdata/baselines/reference/tsc/contentMapperFailures/mapper-is-disabled-after-repeated-failures.js
@@ -40,7 +40,6 @@ tsgo --runExternalCode --singleThreaded
 ExitStatus:: DiagnosticsPresent_OutputsGenerated
 Output::
 error TS100026: The content mapper 'fail' failed 5 times and will not be used.
-
 c.vue:1:1 - error TS100025: The content mapper 'fail' failed to transform this file.
   The content mapper process failed while handling the transform request.
 
diff --git a/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/two-files-exist-on-disk-that-differs-only-in-casing.js b/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/two-files-exist-on-disk-that-differs-only-in-casing.js
index c648ddc9ff1d2..f726afec245e9 100644
--- a/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/two-files-exist-on-disk-that-differs-only-in-casing.js
+++ b/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/two-files-exist-on-disk-that-differs-only-in-casing.js
@@ -23,10 +23,9 @@ Output::
 1 import {x} from "./D"
                   ~~~~~
 
-  tsconfig.json:2:23
+  tsconfig.json:2:23 - File is matched by 'files' list specified here.
     2     "files": ["c.ts", "d.ts"]
                             ~~~~~~
-    File is matched by 'files' list specified here.
 
 
 Found 1 error in c.ts:1
diff --git a/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/when-file-is-included-from-multiple-places-with-different-casing.js b/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/when-file-is-included-from-multiple-places-with-different-casing.js
index 254c084931dda..5c31260cf9c03 100644
--- a/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/when-file-is-included-from-multiple-places-with-different-casing.js
+++ b/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/when-file-is-included-from-multiple-places-with-different-casing.js
@@ -36,26 +36,25 @@ Output::
 2 import * as xs2 from "fp-ts/lib/struct";
                        ~~~~~~~~~~~~~~~~~~
 
-  src/anotherFile.ts:1:22
+  src/anotherFile.ts:1:22 - File is included via import here.
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
-    File is included via import here.
-  src/anotherFile.ts:2:22
+
+  src/anotherFile.ts:2:22 - File is included via import here.
     2 import * as xs2 from "fp-ts/lib/struct";
                            ~~~~~~~~~~~~~~~~~~
-    File is included via import here.
-  src/Struct.d.ts:1:22
+
+  src/Struct.d.ts:1:22 - File is included via import here.
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
-    File is included via import here.
-  src/oneMore.ts:1:22
+
+  src/oneMore.ts:1:22 - File is included via import here.
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
-    File is included via import here.
-  src/oneMore.ts:2:22
+
+  src/oneMore.ts:2:22 - File is included via import here.
     2 import * as xs2 from "fp-ts/lib/struct";
                            ~~~~~~~~~~~~~~~~~~
-    File is included via import here.
 
 src/Struct.d.ts:4:22 - error TS1149: File name '/home/src/projects/project/src/struct.d.ts' differs from already included file name '/home/src/projects/project/src/Struct.d.ts' only in casing.
   The file is in the program because:
@@ -70,26 +69,25 @@ Output::
 4 import * as xs4 from "./struct";
                        ~~~~~~~~~~
 
-  src/anotherFile.ts:3:22
+  src/anotherFile.ts:3:22 - File is included via import here.
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-    File is included via import here.
-  src/Struct.d.ts:3:22
+
+  src/Struct.d.ts:3:22 - File is included via import here.
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-    File is included via import here.
-  src/anotherFile.ts:4:22
+
+  src/anotherFile.ts:4:22 - File is included via import here.
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
-    File is included via import here.
-  src/oneMore.ts:3:22
+
+  src/oneMore.ts:3:22 - File is included via import here.
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-    File is included via import here.
-  src/oneMore.ts:4:22
+
+  src/oneMore.ts:4:22 - File is included via import here.
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
-    File is included via import here.
 
 src/anotherFile.ts:2:22 - error TS1149: File name '/home/src/projects/project/node_modules/fp-ts/lib/struct.d.ts' differs from already included file name '/home/src/projects/project/node_modules/fp-ts/lib/Struct.d.ts' only in casing.
   The file is in the program because:
@@ -103,26 +101,25 @@ Output::
 2 import * as xs2 from "fp-ts/lib/struct";
                        ~~~~~~~~~~~~~~~~~~
 
-  src/anotherFile.ts:1:22
+  src/anotherFile.ts:1:22 - File is included via import here.
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
-    File is included via import here.
-  src/Struct.d.ts:1:22
+
+  src/Struct.d.ts:1:22 - File is included via import here.
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
-    File is included via import here.
-  src/Struct.d.ts:2:22
+
+  src/Struct.d.ts:2:22 - File is included via import here.
     2 import * as xs2 from "fp-ts/lib/struct";
                            ~~~~~~~~~~~~~~~~~~
-    File is included via import here.
-  src/oneMore.ts:1:22
+
+  src/oneMore.ts:1:22 - File is included via import here.
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
-    File is included via import here.
-  src/oneMore.ts:2:22
+
+  src/oneMore.ts:2:22 - File is included via import here.
     2 import * as xs2 from "fp-ts/lib/struct";
                            ~~~~~~~~~~~~~~~~~~
-    File is included via import here.
 
 src/anotherFile.ts:3:22 - error TS1261: Already included file name '/home/src/projects/project/src/Struct.d.ts' differs from file name '/home/src/projects/project/src/struct.d.ts' only in casing.
   The file is in the program because:
@@ -137,26 +134,25 @@ Output::
 3 import * as xs3 from "./Struct";
                        ~~~~~~~~~~
 
-  src/Struct.d.ts:3:22
+  src/Struct.d.ts:3:22 - File is included via import here.
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-    File is included via import here.
-  src/Struct.d.ts:4:22
+
+  src/Struct.d.ts:4:22 - File is included via import here.
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
-    File is included via import here.
-  src/anotherFile.ts:4:22
+
+  src/anotherFile.ts:4:22 - File is included via import here.
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
-    File is included via import here.
-  src/oneMore.ts:3:22
+
+  src/oneMore.ts:3:22 - File is included via import here.
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-    File is included via import here.
-  src/oneMore.ts:4:22
+
+  src/oneMore.ts:4:22 - File is included via import here.
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
-    File is included via import here.
 
 src/anotherFile.ts:4:22 - error TS1149: File name '/home/src/projects/project/src/struct.d.ts' differs from already included file name '/home/src/projects/project/src/Struct.d.ts' only in casing.
   The file is in the program because:
@@ -171,26 +167,25 @@ Output::
 4 import * as xs4 from "./struct";
                        ~~~~~~~~~~
 
-  src/anotherFile.ts:3:22
+  src/anotherFile.ts:3:22 - File is included via import here.
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-    File is included via import here.
-  src/Struct.d.ts:3:22
+
+  src/Struct.d.ts:3:22 - File is included via import here.
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-    File is included via import here.
-  src/Struct.d.ts:4:22
+
+  src/Struct.d.ts:4:22 - File is included via import here.
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
-    File is included via import here.
-  src/oneMore.ts:3:22
+
+  src/oneMore.ts:3:22 - File is included via import here.
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-    File is included via import here.
-  src/oneMore.ts:4:22
+
+  src/oneMore.ts:4:22 - File is included via import here.
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
-    File is included via import here.
 
 src/oneMore.ts:2:22 - error TS1149: File name '/home/src/projects/project/node_modules/fp-ts/lib/struct.d.ts' differs from already included file name '/home/src/projects/project/node_modules/fp-ts/lib/Struct.d.ts' only in casing.
   The file is in the program because:
@@ -204,26 +199,25 @@ Output::
 2 import * as xs2 from "fp-ts/lib/struct";
                        ~~~~~~~~~~~~~~~~~~
 
-  src/anotherFile.ts:1:22
+  src/anotherFile.ts:1:22 - File is included via import here.
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
-    File is included via import here.
-  src/anotherFile.ts:2:22
+
+  src/anotherFile.ts:2:22 - File is included via import here.
     2 import * as xs2 from "fp-ts/lib/struct";
                            ~~~~~~~~~~~~~~~~~~
-    File is included via import here.
-  src/Struct.d.ts:1:22
+
+  src/Struct.d.ts:1:22 - File is included via import here.
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
-    File is included via import here.
-  src/Struct.d.ts:2:22
+
+  src/Struct.d.ts:2:22 - File is included via import here.
     2 import * as xs2 from "fp-ts/lib/struct";
                            ~~~~~~~~~~~~~~~~~~
-    File is included via import here.
-  src/oneMore.ts:1:22
+
+  src/oneMore.ts:1:22 - File is included via import here.
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
-    File is included via import here.
 
 src/oneMore.ts:4:22 - error TS1149: File name '/home/src/projects/project/src/struct.d.ts' differs from already included file name '/home/src/projects/project/src/Struct.d.ts' only in casing.
   The file is in the program because:
@@ -238,26 +232,25 @@ Output::
 4 import * as xs4 from "./struct";
                        ~~~~~~~~~~
 
-  src/anotherFile.ts:3:22
+  src/anotherFile.ts:3:22 - File is included via import here.
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-    File is included via import here.
-  src/Struct.d.ts:3:22
+
+  src/Struct.d.ts:3:22 - File is included via import here.
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-    File is included via import here.
-  src/Struct.d.ts:4:22
+
+  src/Struct.d.ts:4:22 - File is included via import here.
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
-    File is included via import here.
-  src/anotherFile.ts:4:22
+
+  src/anotherFile.ts:4:22 - File is included via import here.
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
-    File is included via import here.
-  src/oneMore.ts:3:22
+
+  src/oneMore.ts:3:22 - File is included via import here.
     3 import * as xs3 from "./Struct";
                            ~~~~~~~~~~
-    File is included via import here.
 
 ../../tslibs/TS/Lib/lib.es2025.full.d.ts
    Default library for target 'ES2025'
diff --git a/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/with-relative-and-non-relative-file-resolutions.js b/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/with-relative-and-non-relative-file-resolutions.js
index f4808d4d1fdc1..cb332937d4fa1 100644
--- a/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/with-relative-and-non-relative-file-resolutions.js
+++ b/tsc/testdata/baselines/reference/tsc/forceConsistentCasingInFileNames/with-relative-and-non-relative-file-resolutions.js
@@ -20,10 +20,9 @@ Output::
 2 import * as xs2 from "fp-ts/lib/struct";
                        ~~~~~~~~~~~~~~~~~~
 
-  src/struct.d.ts:1:22
+  src/struct.d.ts:1:22 - File is included via import here.
     1 import * as xs1 from "fp-ts/lib/Struct";
                            ~~~~~~~~~~~~~~~~~~
-    File is included via import here.
 
 src/struct.d.ts:3:22 - error TS1149: File name '/user/username/projects/myproject/src/Struct.d.ts' differs from already included file name '/user/username/projects/myproject/src/struct.d.ts' only in casing.
   The file is in the program because:
@@ -34,10 +33,9 @@ Output::
 3 import * as xs3 from "./Struct";
                        ~~~~~~~~~~
 
-  src/struct.d.ts:4:22
+  src/struct.d.ts:4:22 - File is included via import here.
     4 import * as xs4 from "./struct";
                            ~~~~~~~~~~
-    File is included via import here.
 
 ../../../../home/src/tslibs/TS/Lib/lib.es2025.full.d.ts
    Default library for target 'ES2025'
diff --git a/tsc/testdata/baselines/reference/tsc/generateTrace/generateTrace-with-multiple-files-and-complex-types.js b/tsc/testdata/baselines/reference/tsc/generateTrace/generateTrace-with-multiple-files-and-complex-types.js
index b2f228804fd92..befa8be5368c2 100644
--- a/tsc/testdata/baselines/reference/tsc/generateTrace/generateTrace-with-multiple-files-and-complex-types.js
+++ b/tsc/testdata/baselines/reference/tsc/generateTrace/generateTrace-with-multiple-files-and-complex-types.js
@@ -31,10 +31,9 @@ Output::
 2 const c: Container<number> = { value: 42, map: (fn) => ({ value: fn(42), map: c.map }) };
                                                                            ~~~
 
-  types.ts:3:5
+  types.ts:3:5 - The expected type comes from property 'map' which is declared here on type 'Container<U>'
     3     map<U>(fn: (x: T) => U): Container<U>;
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-    The expected type comes from property 'map' which is declared here on type 'Container<U>'
 
 
 Found 1 error in main.ts:2
diff --git a/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-when-config-file-absent-with---ignoreConfig.js b/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-when-config-file-absent-with---ignoreConfig.js
index 36d1767af4c7d..74d6e078632f8 100644
--- a/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-when-config-file-absent-with---ignoreConfig.js
+++ b/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-when-config-file-absent-with---ignoreConfig.js
@@ -13,4 +13,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5042: Option 'project' cannot be mixed with source files on a command line.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-when-config-file-absent.js b/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-when-config-file-absent.js
index de5d158171559..c557a4537a6d2 100644
--- a/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-when-config-file-absent.js
+++ b/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-when-config-file-absent.js
@@ -13,4 +13,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5042: Option 'project' cannot be mixed with source files on a command line.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-with---ignoreConfig.js b/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-with---ignoreConfig.js
index e8f3de2c08556..f325237920c83 100644
--- a/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-with---ignoreConfig.js
+++ b/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files-with---ignoreConfig.js
@@ -17,4 +17,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5042: Option 'project' cannot be mixed with source files on a command line.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files.js b/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files.js
index 38658f4416efa..35141cbcc6df7 100644
--- a/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files.js
+++ b/tsc/testdata/baselines/reference/tsc/ignoreConfig/mixing-project-and-files.js
@@ -17,4 +17,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5042: Option 'project' cannot be mixed with source files on a command line.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-files.js b/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-files.js
index 823191d8e5859..fab3875627728 100644
--- a/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-files.js
+++ b/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-files.js
@@ -17,4 +17,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5112: tsconfig.json is present but will not be loaded if files are specified on commandline. Use '--ignoreConfig' to skip this error.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-project-when-config-file-absent-with---ignoreConfig.js b/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-project-when-config-file-absent-with---ignoreConfig.js
index 5c8058ed0117a..ed09be7914a74 100644
--- a/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-project-when-config-file-absent-with---ignoreConfig.js
+++ b/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-project-when-config-file-absent-with---ignoreConfig.js
@@ -13,4 +13,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5081: Cannot find a tsconfig.json file at the current directory: /home/src/workspaces/project/tsconfig.json.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-project-when-config-file-absent.js b/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-project-when-config-file-absent.js
index 4a2bdf2b1c817..c8d7560ae5573 100644
--- a/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-project-when-config-file-absent.js
+++ b/tsc/testdata/baselines/reference/tsc/ignoreConfig/specifying-project-when-config-file-absent.js
@@ -13,4 +13,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5081: Cannot find a tsconfig.json file at the current directory: /home/src/workspaces/project/tsconfig.json.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/incremental/Compile-incremental-with-case-insensitive-file-names.js b/tsc/testdata/baselines/reference/tsc/incremental/Compile-incremental-with-case-insensitive-file-names.js
index 922fd45f1e736..3d384abf36137 100644
--- a/tsc/testdata/baselines/reference/tsc/incremental/Compile-incremental-with-case-insensitive-file-names.js
+++ b/tsc/testdata/baselines/reference/tsc/incremental/Compile-incremental-with-case-insensitive-file-names.js
@@ -52,10 +52,9 @@ Output::
 1 import type { Foo } from 'somelib';
                            ~~~~~~~~~
 
-  ../node_modules/lib1/index.d.ts:1:26
+  ../node_modules/lib1/index.d.ts:1:26 - File is included via import here.
     1 import type { Foo } from 'someLib';
                                ~~~~~~~~~
-    File is included via import here.
 
 
 Found 1 error in ../node_modules/lib2/index.d.ts:1
diff --git a/tsc/testdata/baselines/reference/tsc/incremental/change-to-modifier-of-class-expression-field-with-declaration-emit-enabled.js b/tsc/testdata/baselines/reference/tsc/incremental/change-to-modifier-of-class-expression-field-with-declaration-emit-enabled.js
index 8577ec9763930..4a7e96ec311d9 100644
--- a/tsc/testdata/baselines/reference/tsc/incremental/change-to-modifier-of-class-expression-field-with-declaration-emit-enabled.js
+++ b/tsc/testdata/baselines/reference/tsc/incremental/change-to-modifier-of-class-expression-field-with-declaration-emit-enabled.js
@@ -269,10 +269,9 @@ Output::
 6 const wrapper = () => Messageable();
         ~~~~~~~
 
-  MessageablePerson.ts:6:7
+  MessageablePerson.ts:6:7 - Add a type annotation to the variable wrapper.
     6 const wrapper = () => Messageable();
             ~~~~~~~
-    Add a type annotation to the variable wrapper.
 
 MessageablePerson.ts:7:26 - error TS2304: Cannot find name 'InstanceType'.
 
@@ -440,10 +439,9 @@ Output::
 6 const wrapper = () => Messageable();
         ~~~~~~~
 
-  MessageablePerson.ts:6:7
+  MessageablePerson.ts:6:7 - Add a type annotation to the variable wrapper.
     6 const wrapper = () => Messageable();
             ~~~~~~~
-    Add a type annotation to the variable wrapper.
 
 MessageablePerson.ts:7:26 - error TS2304: Cannot find name 'InstanceType'.
 
diff --git a/tsc/testdata/baselines/reference/tsc/incremental/internal-symbolname-in-tsbuildInfo.js b/tsc/testdata/baselines/reference/tsc/incremental/internal-symbolname-in-tsbuildInfo.js
index 9ca161633691c..e33fcabf4b84f 100644
--- a/tsc/testdata/baselines/reference/tsc/incremental/internal-symbolname-in-tsbuildInfo.js
+++ b/tsc/testdata/baselines/reference/tsc/incremental/internal-symbolname-in-tsbuildInfo.js
@@ -100,10 +100,9 @@ Output::
 3     length: files.length,
       ~~~~~~~~~~~~~~~~~~~~
 
-  a.ts:8:5
+  a.ts:8:5 - This spread always overwrites this property.
     8     ...files,
           ~~~~~~~~
-    This spread always overwrites this property.
 
 a.ts:5:5 - error TS2783: '�@iterator@<symbolId>' is specified more than once, so this usage will be overwritten.
 
@@ -114,10 +113,9 @@ Output::
 7     },
   ~~~~~
 
-  a.ts:8:5
+  a.ts:8:5 - This spread always overwrites this property.
     8     ...files,
           ~~~~~~~~
-    This spread always overwrites this property.
 
 
 Found 2 errors in the same file, starting at: a.ts:3
@@ -145,10 +143,9 @@ Output::
 3     length: files.length,
       ~~~~~~~~~~~~~~~~~~~~
 
-  a.ts:8:5
+  a.ts:8:5 - This spread always overwrites this property.
     8     ...files,
           ~~~~~~~~
-    This spread always overwrites this property.
 
 a.ts:5:5 - error TS2783: '�@iterator@<symbolId>' is specified more than once, so this usage will be overwritten.
 
@@ -159,10 +156,9 @@ Output::
 7     },
   ~~~~~
 
-  a.ts:8:5
+  a.ts:8:5 - This spread always overwrites this property.
     8     ...files,
           ~~~~~~~~
-    This spread always overwrites this property.
 
 
 Found 2 errors in the same file, starting at: a.ts:3
@@ -181,10 +177,9 @@ Output::
 3     length: files.length,
       ~~~~~~~~~~~~~~~~~~~~
 
-  a.ts:8:5
+  a.ts:8:5 - This spread always overwrites this property.
     8     ...files,
           ~~~~~~~~
-    This spread always overwrites this property.
 
 a.ts:5:5 - error TS2783: '�@iterator@<symbolId>' is specified more than once, so this usage will be overwritten.
 
@@ -195,10 +190,9 @@ Output::
 7     },
   ~~~~~
 
-  a.ts:8:5
+  a.ts:8:5 - This spread always overwrites this property.
     8     ...files,
           ~~~~~~~~
-    This spread always overwrites this property.
 
 
 Found 2 errors in the same file, starting at: a.ts:3
@@ -331,10 +325,9 @@ Output::
 3     length: files.length,
       ~~~~~~~~~~~~~~~~~~~~
 
-  a.ts:8:5
+  a.ts:8:5 - This spread always overwrites this property.
     8     ...files,
           ~~~~~~~~
-    This spread always overwrites this property.
 
 a.ts:5:5 - error TS2783: '�@iterator@<symbolId>' is specified more than once, so this usage will be overwritten.
 
@@ -345,10 +338,9 @@ Output::
 7     },
   ~~~~~
 
-  a.ts:8:5
+  a.ts:8:5 - This spread always overwrites this property.
     8     ...files,
           ~~~~~~~~
-    This spread always overwrites this property.
 
 
 Found 2 errors in the same file, starting at: a.ts:3
diff --git a/tsc/testdata/baselines/reference/tsc/incremental/js-file-with-import-in-jsdoc-in-composite-project.js b/tsc/testdata/baselines/reference/tsc/incremental/js-file-with-import-in-jsdoc-in-composite-project.js
index 36dd0315a0246..2cacb067b1ce2 100644
--- a/tsc/testdata/baselines/reference/tsc/incremental/js-file-with-import-in-jsdoc-in-composite-project.js
+++ b/tsc/testdata/baselines/reference/tsc/incremental/js-file-with-import-in-jsdoc-in-composite-project.js
@@ -32,7 +32,6 @@ ExitStatus:: DiagnosticsPresent_OutputsGenerated
 Output::
 error TS2318: Cannot find global type 'Promise'.
 
-
 Found 1 error.
 
 //// [/home/src/tslibs/TS/Lib/lib.es2025.full.d.ts] *Lib*
diff --git a/tsc/testdata/baselines/reference/tsc/incremental/serializing-error-chain.js b/tsc/testdata/baselines/reference/tsc/incremental/serializing-error-chain.js
index 3ec10629a3531..8d4c59f060791 100644
--- a/tsc/testdata/baselines/reference/tsc/incremental/serializing-error-chain.js
+++ b/tsc/testdata/baselines/reference/tsc/incremental/serializing-error-chain.js
@@ -37,10 +37,9 @@ Output::
 10 (<Component>
      ~~~~~~~~~
 
-  index.tsx:9:18
+  index.tsx:9:18 - The last overload is declared here.
     9 declare function Component(props: { children?: number }): any;
                        ~~~~~~~~~
-    The last overload is declared here.
 
 
 Found 1 error in index.tsx:10
@@ -216,10 +215,9 @@ Output::
 10 (<Component>
      ~~~~~~~~~
 
-  index.tsx:9:18
+  index.tsx:9:18 - The last overload is declared here.
     9 declare function Component(props: { children?: number }): any;
                        ~~~~~~~~~
-    The last overload is declared here.
 
 
 Found 1 error in index.tsx:10
diff --git a/tsc/testdata/baselines/reference/tsc/libraryResolution/when-noLib-toggles.js b/tsc/testdata/baselines/reference/tsc/libraryResolution/when-noLib-toggles.js
index f431804b71919..1b616dd558d32 100644
--- a/tsc/testdata/baselines/reference/tsc/libraryResolution/when-noLib-toggles.js
+++ b/tsc/testdata/baselines/reference/tsc/libraryResolution/when-noLib-toggles.js
@@ -129,25 +129,15 @@ tsgo --noLib
 ExitStatus:: DiagnosticsPresent_OutputsGenerated
 Output::
 error TS2318: Cannot find global type 'Array'.
-
 error TS2318: Cannot find global type 'Boolean'.
-
 error TS2318: Cannot find global type 'CallableFunction'.
-
 error TS2318: Cannot find global type 'Function'.
-
 error TS2318: Cannot find global type 'IArguments'.
-
 error TS2318: Cannot find global type 'NewableFunction'.
-
 error TS2318: Cannot find global type 'Number'.
-
 error TS2318: Cannot find global type 'Object'.
-
 error TS2318: Cannot find global type 'RegExp'.
-
 error TS2318: Cannot find global type 'String'.
-
 tsconfig.json:5:9 - error TS5053: Option 'lib' cannot be specified with option 'noLib'.
 
 5         "lib": ["es6"],
diff --git a/tsc/testdata/baselines/reference/tsc/noCheck/dts-errors-with-incremental.js b/tsc/testdata/baselines/reference/tsc/noCheck/dts-errors-with-incremental.js
index 1c72c4656f665..1a8b5b0cabf41 100644
--- a/tsc/testdata/baselines/reference/tsc/noCheck/dts-errors-with-incremental.js
+++ b/tsc/testdata/baselines/reference/tsc/noCheck/dts-errors-with-incremental.js
@@ -21,10 +21,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -176,10 +175,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -410,10 +408,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -537,10 +534,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -562,10 +558,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -965,10 +960,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsc/noCheck/dts-errors.js b/tsc/testdata/baselines/reference/tsc/noCheck/dts-errors.js
index 023d11545620a..860941f8f918d 100644
--- a/tsc/testdata/baselines/reference/tsc/noCheck/dts-errors.js
+++ b/tsc/testdata/baselines/reference/tsc/noCheck/dts-errors.js
@@ -21,10 +21,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -76,10 +75,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -168,10 +166,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -196,10 +193,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -220,10 +216,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -302,10 +297,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/changes-composite.js b/tsc/testdata/baselines/reference/tsc/noEmit/changes-composite.js
index 64fdb8d4fa1c2..f0dbfd1471c69 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/changes-composite.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/changes-composite.js
@@ -337,20 +337,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -912,20 +910,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1189,20 +1185,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1233,20 +1227,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1277,20 +1269,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1321,20 +1311,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/changes-incremental-declaration.js b/tsc/testdata/baselines/reference/tsc/noEmit/changes-incremental-declaration.js
index ecc408c9f6017..5f3fc47d20272 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/changes-incremental-declaration.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/changes-incremental-declaration.js
@@ -336,20 +336,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -887,20 +885,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1166,20 +1162,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1210,20 +1204,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1254,20 +1246,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1298,20 +1288,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/changes-incremental.js b/tsc/testdata/baselines/reference/tsc/noEmit/changes-incremental.js
index c43702d84746f..bb3c5c7a2c2d0 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/changes-incremental.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/changes-incremental.js
@@ -278,20 +278,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -805,20 +803,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1057,20 +1053,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1101,20 +1095,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1145,20 +1137,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
@@ -1189,20 +1179,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-composite.js b/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-composite.js
index 84c9317bfba8f..ecf00bb71e79e 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-composite.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-composite.js
@@ -503,20 +503,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-incremental-declaration.js b/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-incremental-declaration.js
index 941ecb922a353..b09fc9259fdb2 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-incremental-declaration.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-incremental-declaration.js
@@ -476,20 +476,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-incremental.js b/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-incremental.js
index 2c8d04e9aef50..138d0771c84bf 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-incremental.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-incremental.js
@@ -415,20 +415,18 @@ Output::
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/indirectUse.ts:2:28 - error TS2551: Property 'prop' does not exist on type 'classC'. Did you mean 'prop1'?
 
 2 new indirectClass().classC.prop;
                              ~~~~
 
-  src/class.ts:2:5
+  src/class.ts:2:5 - 'prop1' is declared here.
     2     prop1 = 1;
           ~~~~~
-    'prop1' is declared here.
 
 src/noChangeFileWithEmitSpecificError.ts:1:19 - error TS1100: Invalid use of 'arguments' in strict mode.
 
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-declaration-enable-changes-with-multiple-files.js b/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-declaration-enable-changes-with-multiple-files.js
index 2ff505456cdc3..8c767972d02b3 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-declaration-enable-changes-with-multiple-files.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-declaration-enable-changes-with-multiple-files.js
@@ -162,30 +162,27 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 c.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14
+  c.ts:1:14 - Add a type annotation to the variable c.
     1 export const c = class { private p = 10; };
                    ~
-    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14
+  d.ts:1:14 - Add a type annotation to the variable d.
     1 export const d = class { private p = 10; };
                    ~
-    Add a type annotation to the variable d.
 
 
 Found 3 errors in 3 files.
@@ -397,30 +394,27 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 c.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14
+  c.ts:1:14 - Add a type annotation to the variable c.
     1 export const c = class { private p = 10; };
                    ~
-    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14
+  d.ts:1:14 - Add a type annotation to the variable d.
     1 export const d = class { private p = 10; };
                    ~
-    Add a type annotation to the variable d.
 
 
 Found 3 errors in 3 files.
@@ -644,30 +638,27 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 c.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14
+  c.ts:1:14 - Add a type annotation to the variable c.
     1 export const c = class { private p = 10; };
                    ~
-    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14
+  d.ts:1:14 - Add a type annotation to the variable d.
     1 export const d = class { private p = 10; };
                    ~
-    Add a type annotation to the variable d.
 
 
 Found 3 errors in 3 files.
@@ -1026,20 +1017,18 @@ Output::
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14
+  c.ts:1:14 - Add a type annotation to the variable c.
     1 export const c = class { private p = 10; };
                    ~
-    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14
+  d.ts:1:14 - Add a type annotation to the variable d.
     1 export const d = class { private p = 10; };
                    ~
-    Add a type annotation to the variable d.
 
 
 Found 2 errors in 2 files.
@@ -1233,20 +1222,18 @@ Output::
 1 export const c = class { private p = 10; };
                ~
 
-  c.ts:1:14
+  c.ts:1:14 - Add a type annotation to the variable c.
     1 export const c = class { private p = 10; };
                    ~
-    Add a type annotation to the variable c.
 
 d.ts:1:14 - error TS4094: Property 'p' of exported anonymous class type may not be private or protected.
 
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14
+  d.ts:1:14 - Add a type annotation to the variable d.
     1 export const d = class { private p = 10; };
                    ~
-    Add a type annotation to the variable d.
 
 
 Found 2 errors in 2 files.
@@ -1443,10 +1430,9 @@ Output::
 1 export const d = class { private p = 10; };
                ~
 
-  d.ts:1:14
+  d.ts:1:14 - Add a type annotation to the variable d.
     1 export const d = class { private p = 10; };
                    ~
-    Add a type annotation to the variable d.
 
 
 Found 1 error in d.ts:1
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-incremental-as-modules.js b/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-incremental-as-modules.js
index d389e09e987eb..883fa4cd4945f 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-incremental-as-modules.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-incremental-as-modules.js
@@ -21,10 +21,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -171,10 +170,9 @@ Output::
 1 export const a = class { private p = 10; };
                ~
 
-  a.ts:1:14
+  a.ts:1:14 - Add a type annotation to the variable a.
     1 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -397,10 +395,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -538,10 +535,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -664,10 +660,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-incremental.js b/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-incremental.js
index 4a41de5c3b6ea..7f8fd52fd1db0 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-incremental.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors-with-incremental.js
@@ -19,10 +19,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -155,10 +154,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -345,10 +343,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -460,10 +457,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -568,10 +564,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors.js b/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors.js
index 531ebea6d489c..299fdcb8dacde 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmit/dts-errors.js
@@ -19,10 +19,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -63,10 +62,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -127,10 +125,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -148,10 +145,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -175,10 +171,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/baselines/reference/tsc/noEmitOnError/dts-errors-with-declaration-with-incremental.js b/tsc/testdata/baselines/reference/tsc/noEmitOnError/dts-errors-with-declaration-with-incremental.js
index a7186d8a190ef..b1e3920ac2372 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmitOnError/dts-errors-with-declaration-with-incremental.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmitOnError/dts-errors-with-declaration-with-incremental.js
@@ -29,10 +29,9 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14
+  src/main.ts:2:14 - Add a type annotation to the variable a.
     2 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in src/main.ts:2
@@ -208,10 +207,9 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14
+  src/main.ts:2:14 - Add a type annotation to the variable a.
     2 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in src/main.ts:2
diff --git a/tsc/testdata/baselines/reference/tsc/noEmitOnError/dts-errors-with-declaration.js b/tsc/testdata/baselines/reference/tsc/noEmitOnError/dts-errors-with-declaration.js
index 7c0b3491e0c37..75a34f056ecbe 100644
--- a/tsc/testdata/baselines/reference/tsc/noEmitOnError/dts-errors-with-declaration.js
+++ b/tsc/testdata/baselines/reference/tsc/noEmitOnError/dts-errors-with-declaration.js
@@ -29,10 +29,9 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14
+  src/main.ts:2:14 - Add a type annotation to the variable a.
     2 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in src/main.ts:2
@@ -73,10 +72,9 @@ Output::
 2 export const a = class { private p = 10; };
                ~
 
-  src/main.ts:2:14
+  src/main.ts:2:14 - Add a type annotation to the variable a.
     2 export const a = class { private p = 10; };
                    ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in src/main.ts:2
diff --git a/tsc/testdata/baselines/reference/tsc/showConfig/Default-initialized-TSConfig.js b/tsc/testdata/baselines/reference/tsc/showConfig/Default-initialized-TSConfig.js
index b25098501b866..b61895595f13b 100644
--- a/tsc/testdata/baselines/reference/tsc/showConfig/Default-initialized-TSConfig.js
+++ b/tsc/testdata/baselines/reference/tsc/showConfig/Default-initialized-TSConfig.js
@@ -7,4 +7,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5081: Cannot find a tsconfig.json file at the current directory: /home/src/workspaces/project.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-advanced-options.js b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-advanced-options.js
index c9da5e87c69f4..df5a6782c2511 100644
--- a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-advanced-options.js
+++ b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-advanced-options.js
@@ -7,4 +7,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5081: Cannot find a tsconfig.json file at the current directory: /home/src/workspaces/project.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-boolean-value-compiler-options.js b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-boolean-value-compiler-options.js
index ef73c3042b511..da30c08a19cfb 100644
--- a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-boolean-value-compiler-options.js
+++ b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-boolean-value-compiler-options.js
@@ -7,4 +7,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5081: Cannot find a tsconfig.json file at the current directory: /home/src/workspaces/project.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-enum-value-compiler-options.js b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-enum-value-compiler-options.js
index 0a6957c4d5b27..bf3ed802f92a2 100644
--- a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-enum-value-compiler-options.js
+++ b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-enum-value-compiler-options.js
@@ -7,4 +7,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5081: Cannot find a tsconfig.json file at the current directory: /home/src/workspaces/project.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-incorrect-compiler-option-value.js b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-incorrect-compiler-option-value.js
index 0ae2a3ab700cb..7902a5f89cdfd 100644
--- a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-incorrect-compiler-option-value.js
+++ b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-incorrect-compiler-option-value.js
@@ -7,4 +7,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS6046: Argument for '--lib' option must be: 'es5', 'es6', 'es2015', 'es7', 'es2016', 'es2017', 'es2018', 'es2019', 'es2020', 'es2021', 'es2022', 'es2023', 'es2024', 'es2025', 'esnext', 'dom', 'dom.iterable', 'dom.asynciterable', 'webworker', 'webworker.importscripts', 'webworker.iterable', 'webworker.asynciterable', 'scripthost', 'es2015.core', 'es2015.collection', 'es2015.generator', 'es2015.iterable', 'es2015.promise', 'es2015.proxy', 'es2015.reflect', 'es2015.symbol', 'es2015.symbol.wellknown', 'es2016.array.include', 'es2016.intl', 'es2017.arraybuffer', 'es2017.date', 'es2017.object', 'es2017.sharedmemory', 'es2017.string', 'es2017.intl', 'es2017.typedarrays', 'es2018.asyncgenerator', 'es2018.asynciterable', 'es2018.intl', 'es2018.promise', 'es2018.regexp', 'es2019.array', 'es2019.object', 'es2019.string', 'es2019.symbol', 'es2019.intl', 'es2020.bigint', 'es2020.date', 'es2020.promise', 'es2020.sharedmemory', 'es2020.string', 'es2020.symbol.wellknown', 'es2020.intl', 'es2020.number', 'es2021.promise', 'es2021.string', 'es2021.weakref', 'es2021.intl', 'es2022.array', 'es2022.error', 'es2022.intl', 'es2022.object', 'es2022.string', 'es2022.regexp', 'es2023.array', 'es2023.collection', 'es2023.intl', 'es2024.arraybuffer', 'es2024.collection', 'es2024.object', 'es2024.promise', 'es2024.regexp', 'es2024.sharedmemory', 'es2024.string', 'es2025.collection', 'es2025.float16', 'es2025.intl', 'es2025.iterator', 'es2025.promise', 'es2025.regexp', 'esnext.asynciterable', 'esnext.symbol', 'esnext.bigint', 'esnext.weakref', 'esnext.object', 'esnext.regexp', 'esnext.string', 'esnext.float16', 'esnext.iterator', 'esnext.promise', 'esnext.array', 'esnext.collection', 'esnext.date', 'esnext.decorators', 'esnext.disposable', 'esnext.error', 'esnext.intl', 'esnext.sharedmemory', 'esnext.temporal', 'esnext.typedarrays', 'decorators', 'decorators.legacy'.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-incorrect-compiler-option.js b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-incorrect-compiler-option.js
index a01eddac525c2..d922215b52019 100644
--- a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-incorrect-compiler-option.js
+++ b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-incorrect-compiler-option.js
@@ -7,4 +7,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5023: Unknown compiler option '--someNonExistOption'.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-list-compiler-options-with-enum-value.js b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-list-compiler-options-with-enum-value.js
index 9a2c1c938b110..2677c20cc1436 100644
--- a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-list-compiler-options-with-enum-value.js
+++ b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-list-compiler-options-with-enum-value.js
@@ -7,4 +7,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5081: Cannot find a tsconfig.json file at the current directory: /home/src/workspaces/project.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-list-compiler-options.js b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-list-compiler-options.js
index 7ecf617395dca..82fb9636f8fba 100644
--- a/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-list-compiler-options.js
+++ b/tsc/testdata/baselines/reference/tsc/showConfig/Show-TSConfig-with-list-compiler-options.js
@@ -7,4 +7,3 @@ ExitStatus:: DiagnosticsPresent_OutputsSkipped
 Output::
 error TS5081: Cannot find a tsconfig.json file at the current directory: /home/src/workspaces/project.
 
-
diff --git a/tsc/testdata/baselines/reference/tsc/typeAcquisition/parse-tsconfig-with-typeAcquisition.js b/tsc/testdata/baselines/reference/tsc/typeAcquisition/parse-tsconfig-with-typeAcquisition.js
index 274d196898080..5c89ebdf9aa8d 100644
--- a/tsc/testdata/baselines/reference/tsc/typeAcquisition/parse-tsconfig-with-typeAcquisition.js
+++ b/tsc/testdata/baselines/reference/tsc/typeAcquisition/parse-tsconfig-with-typeAcquisition.js
@@ -20,7 +20,6 @@ ExitStatus:: DiagnosticsPresent_OutputsGenerated
 Output::
 error TS18003: No inputs were found in config file '/home/src/workspaces/project/tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
 
-
 Found 1 error.
 
 //// [/home/src/workspaces/project/tsconfig.tsbuildinfo] *new* 
diff --git a/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-detects-nested-subdirectory-removed-and-recreated.js b/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-detects-nested-subdirectory-removed-and-recreated.js
index 9939bf70ffaee..4cdb0864eaa82 100644
--- a/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-detects-nested-subdirectory-removed-and-recreated.js
+++ b/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-detects-nested-subdirectory-removed-and-recreated.js
@@ -77,10 +77,9 @@ Signatures::
 Diff:: incremental has prior state and does not report no-inputs error
 --- nonIncremental.output.txt
 +++ incremental.output.txt
-@@ -1,5 +0,0 @@
+@@ -1,4 +0,0 @@
 -error TS18003: No inputs were found in config file '/home/src/workspaces/project/tsconfig.json'. Specified 'include' paths were '["src/**/*.ts"]' and 'exclude' paths were '[]'.
 -
--
 -Found 1 error.
 -
 
diff --git a/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-handles-tsconfig-deleted.js b/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-handles-tsconfig-deleted.js
index 18d8af2db3364..7c3ab632e031c 100644
--- a/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-handles-tsconfig-deleted.js
+++ b/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-handles-tsconfig-deleted.js
@@ -58,7 +58,6 @@ Edit [0]:: delete tsconfig
 
 Output::
 error TS5083: Cannot read file '/home/src/workspaces/project/tsconfig.json'.
-
 [HH:MM:SS AM] Found 1 error. Watching for file changes.
 
 
@@ -71,7 +70,7 @@ Directory watches::
 Diff:: incremental reports config read error while clean build without tsconfig prints usage help
 --- nonIncremental.output.txt
 +++ incremental.output.txt
-@@ -1,144 +1,2 @@
+@@ -1,144 +1,1 @@
 -Version FakeTSVersion
 -tsc: The TypeScript Compiler - Version FakeTSVersion
 -
@@ -215,4 +214,5 @@ Diff:: incremental reports config read error while clean build without tsconfig
 -default: true
 -
 -You can learn about all of the compiler options at https://aka.ms/tsc
-+error TS5083: Cannot read file '/home/src/workspaces/project/tsconfig.json'.
+-
++error TS5083: Cannot read file '/home/src/workspaces/project/tsconfig.json'.
\ No newline at end of file
diff --git a/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-with-tsconfig-files-list-entry-deleted.js b/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-with-tsconfig-files-list-entry-deleted.js
index e48f05f7a5c8c..1b0917365955e 100644
--- a/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-with-tsconfig-files-list-entry-deleted.js
+++ b/tsc/testdata/baselines/reference/tscWatch/commandLineWatch/watch-with-tsconfig-files-list-entry-deleted.js
@@ -70,11 +70,9 @@ Output::
 error TS6053: File '/home/src/workspaces/project/b.ts' not found.
   The file is in the program because:
     Part of 'files' list in tsconfig.json
-
-  tsconfig.json:3:20
+  tsconfig.json:3:20 - File is matched by 'files' list specified here.
     3  "files": ["a.ts", "b.ts"]
                          ~~~~~~
-    File is matched by 'files' list specified here.
 
 
 Found 1 error.
diff --git a/tsc/testdata/baselines/reference/tscWatch/noEmit/dts-errors.js b/tsc/testdata/baselines/reference/tscWatch/noEmit/dts-errors.js
index 569570c44d951..c0a2db979bfec 100644
--- a/tsc/testdata/baselines/reference/tscWatch/noEmit/dts-errors.js
+++ b/tsc/testdata/baselines/reference/tscWatch/noEmit/dts-errors.js
@@ -21,10 +21,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -158,10 +157,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -198,10 +196,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
@@ -242,10 +239,9 @@ Output::
 1 const a = class { private p = 10; };
         ~
 
-  a.ts:1:7
+  a.ts:1:7 - Add a type annotation to the variable a.
     1 const a = class { private p = 10; };
             ~
-    Add a type annotation to the variable a.
 
 
 Found 1 error in a.ts:1
diff --git a/tsc/testdata/submoduleAccepted.txt b/tsc/testdata/submoduleAccepted.txt
index 34729fd0ffea5..b2c6f97649d0a 100644
--- a/tsc/testdata/submoduleAccepted.txt
+++ b/tsc/testdata/submoduleAccepted.txt
@@ -671,7 +671,10 @@ conformance/circular1.errors.txt.diff
 conformance/circular3.errors.txt.diff
 
 ## Related spans in various errors changed (these baselines are all --pretty)
+compiler/deeplyNestedAssignabilityIssue.errors.txt.diff
+compiler/esModuleInteropPrettyErrorRelatedInformation.errors.txt.diff
 compiler/prettyContextNotDebugAssertion.errors.txt.diff
+compiler/prettyFileWithErrorsAndTabs.errors.txt.diff
 compiler/manyCompilerErrorsInTheTwoFiles.errors.txt.diff
 
 ## "Call signature return type" layer removed from error pyramid

From fe4cad360155bc8a54357b6d257642d8e4733f9a Mon Sep 17 00:00:00 2001
From: John Favret <64748847+johnfav03@users.noreply.github.com>
Date: Fri, 21 Aug 2026 14:17:22 -0500
Subject: [PATCH 4/6] validate diagnostics with file hashes

---
 packages/typescript/src/api/async/api.ts      | 78 ++++---------------
 .../typescript/src/api/proto.generated.ts     |  5 +-
 packages/typescript/src/api/sync/api.ts       | 78 ++++---------------
 packages/typescript/test/async/api.test.ts    | 61 ++++++++-------
 packages/typescript/test/sync/api.test.ts     | 55 +++++++------
 tsc/internal/api/format_diagnostics.go        | 15 ++--
 tsc/internal/api/proto.go                     | 15 +++-
 tsc/internal/api/proto_test.go                |  1 +
 .../api/session_format_diagnostics_test.go    | 47 ++++++-----
 tsc/internal/tsoptions/tsconfigparsing.go     |  2 +
 10 files changed, 141 insertions(+), 216 deletions(-)

diff --git a/packages/typescript/src/api/async/api.ts b/packages/typescript/src/api/async/api.ts
index 52b034c72aabf..2c903c009d724 100644
--- a/packages/typescript/src/api/async/api.ts
+++ b/packages/typescript/src/api/async/api.ts
@@ -208,54 +208,17 @@ export interface TranspileOutput {
     sourceMapText?: string;
 }
 
-const diagnosticOrigin = globalThis.Symbol("diagnosticOrigin");
-
-interface DiagnosticOrigin {
-    readonly snapshot: number;
-    readonly project: Path;
-}
-
-interface DiagnosticWithOrigin extends Diagnostic {
-    readonly [diagnosticOrigin]?: DiagnosticOrigin;
-}
-
 interface FormatDiagnosticRequest extends Diagnostic {
-    readonly originSnapshot: number;
-    readonly originProject: Path;
     readonly displayFileName?: string;
 }
 
-function associateDiagnostics(
-    diagnostics: readonly Diagnostic[],
-    origin: DiagnosticOrigin,
-): readonly Diagnostic[] {
-    for (const diagnostic of diagnostics) {
-        Object.defineProperty(diagnostic, diagnosticOrigin, { value: origin });
-        if (diagnostic.messageChain) {
-            associateDiagnostics(diagnostic.messageChain, origin);
-        }
-        if (diagnostic.relatedInformation) {
-            associateDiagnostics(diagnostic.relatedInformation, origin);
-        }
-    }
-    return diagnostics;
-}
-
 function toFormatDiagnosticRequest(
     diagnostic: Diagnostic,
-    expectedOrigin: DiagnosticOrigin,
     host: FormatDiagnosticsHost,
 ): FormatDiagnosticRequest {
-    const origin = (diagnostic as DiagnosticWithOrigin)[diagnosticOrigin];
-    if (origin?.snapshot !== expectedOrigin.snapshot || origin.project !== expectedOrigin.project) {
-        throw new Error("Diagnostic was not produced by this program.");
-    }
-
     const { messageChain, relatedInformation, ...diagnosticData } = diagnostic;
     return {
         ...diagnosticData,
-        originSnapshot: origin.snapshot,
-        originProject: origin.project,
         ...(diagnostic.fileName
             ? {
                 displayFileName: convertToRelativePath(
@@ -266,10 +229,10 @@ function toFormatDiagnosticRequest(
             }
             : {}),
         ...(messageChain
-            ? { messageChain: messageChain.map(d => toFormatDiagnosticRequest(d, expectedOrigin, host)) }
+            ? { messageChain: messageChain.map(d => toFormatDiagnosticRequest(d, host)) }
             : {}),
         ...(relatedInformation
-            ? { relatedInformation: relatedInformation.map(d => toFormatDiagnosticRequest(d, expectedOrigin, host)) }
+            ? { relatedInformation: relatedInformation.map(d => toFormatDiagnosticRequest(d, host)) }
             : {}),
     };
 }
@@ -1038,13 +1001,6 @@ export class Program {
         this.toPath = toPath;
     }
 
-    private associateDiagnostics(diagnostics: readonly Diagnostic[]): readonly Diagnostic[] {
-        return associateDiagnostics(diagnostics, {
-            snapshot: this.snapshotId,
-            project: this.project.id,
-        });
-    }
-
     getCompilerOptions(): CompilerOptions {
         return this.project.compilerOptions;
     }
@@ -1181,7 +1137,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return this.associateDiagnostics(data ?? []);
+        return data ?? [];
     }
 
     /**
@@ -1197,7 +1153,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return this.associateDiagnostics(data ?? []);
+        return data ?? [];
     }
 
     /**
@@ -1213,7 +1169,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return this.associateDiagnostics(data ?? []);
+        return data ?? [];
     }
 
     /**
@@ -1229,7 +1185,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return this.associateDiagnostics(data ?? []);
+        return data ?? [];
     }
 
     /**
@@ -1245,7 +1201,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return this.associateDiagnostics(data ?? []);
+        return data ?? [];
     }
 
     /**
@@ -1256,7 +1212,7 @@ export class Program {
             snapshot: this.snapshotId,
             project: this.project.id,
         });
-        return this.associateDiagnostics(data ?? []);
+        return data ?? [];
     }
 
     /**
@@ -1267,7 +1223,7 @@ export class Program {
             snapshot: this.snapshotId,
             project: this.project.id,
         });
-        return this.associateDiagnostics(data ?? []);
+        return data ?? [];
     }
 
     /**
@@ -1278,7 +1234,7 @@ export class Program {
             snapshot: this.snapshotId,
             project: this.project.id,
         });
-        return this.associateDiagnostics(data ?? []);
+        return data ?? [];
     }
 
     /**
@@ -1288,11 +1244,10 @@ export class Program {
         diagnostics: readonly Diagnostic[],
         host: FormatDiagnosticsHost,
     ): Promise<string> {
-        const origin = { snapshot: this.snapshotId, project: this.project.id };
         const data = await this.client.apiRequest("formatDiagnostics", {
             snapshot: this.snapshotId,
             project: this.project.id,
-            diagnostics: diagnostics.map(d => toFormatDiagnosticRequest(d, origin, host)),
+            diagnostics: diagnostics.map(d => toFormatDiagnosticRequest(d, host)),
             newLine: host.getNewLine(),
         });
         return data.output;
@@ -1305,11 +1260,10 @@ export class Program {
         diagnostics: readonly Diagnostic[],
         host: FormatDiagnosticsHost,
     ): Promise<string> {
-        const origin = { snapshot: this.snapshotId, project: this.project.id };
         const data = await this.client.apiRequest("formatDiagnosticsWithColorAndContext", {
             snapshot: this.snapshotId,
             project: this.project.id,
-            diagnostics: diagnostics.map(d => toFormatDiagnosticRequest(d, origin, host)),
+            diagnostics: diagnostics.map(d => toFormatDiagnosticRequest(d, host)),
             newLine: host.getNewLine(),
         });
         return data.output;
@@ -1329,7 +1283,7 @@ export class Program {
         });
         return {
             emitSkipped: response.emitSkipped,
-            diagnostics: this.associateDiagnostics(response.diagnostics),
+            diagnostics: response.diagnostics,
             emittedFiles: response.emittedFiles,
         };
     }
@@ -1343,7 +1297,7 @@ export class Program {
             project: this.project.id,
             ...(emitOnly !== undefined ? { emitOnly } : {}),
         });
-        return toEmitOutput(response, this.associateDiagnostics(response.diagnostics));
+        return toEmitOutput(response, response.diagnostics);
     }
 
     /**
@@ -1355,7 +1309,7 @@ export class Program {
             project: this.project.id,
             files,
         });
-        return toEmitOutput(response, this.associateDiagnostics(response.diagnostics));
+        return toEmitOutput(response, response.diagnostics);
     }
 
     /**
@@ -1367,7 +1321,7 @@ export class Program {
             project: this.project.id,
             files,
         });
-        return toEmitOutput(response, this.associateDiagnostics(response.diagnostics));
+        return toEmitOutput(response, response.diagnostics);
     }
 }
 
diff --git a/packages/typescript/src/api/proto.generated.ts b/packages/typescript/src/api/proto.generated.ts
index f94ba51c85643..8f49e31327626 100644
--- a/packages/typescript/src/api/proto.generated.ts
+++ b/packages/typescript/src/api/proto.generated.ts
@@ -761,6 +761,8 @@ export interface GetDiagnosticsParams {
 export interface DiagnosticResponse {
     /** FileName is the path of the file this diagnostic belongs to, if any. */
     fileName?: string;
+    /** SourceFileHash identifies the source text used to produce this diagnostic. */
+    sourceFileHash?: string;
     /** Pos is the start position of the diagnostic in the source file. */
     pos: number;
     /** End is the end position of the diagnostic in the source file. */
@@ -781,9 +783,6 @@ export interface DiagnosticResponse {
     messageChain?: DiagnosticResponse[];
     /** RelatedInformation contains related diagnostic information, if any. */
     relatedInformation?: DiagnosticResponse[];
-    /** OriginSnapshot and OriginProject identify the program that produced this diagnostic. */
-    originSnapshot?: number;
-    originProject?: string;
     /** DisplayFileName is the host-formatted file name used only for diagnostic output. */
     displayFileName?: string;
 }
diff --git a/packages/typescript/src/api/sync/api.ts b/packages/typescript/src/api/sync/api.ts
index 143859d8fa50c..6934d4f86a418 100644
--- a/packages/typescript/src/api/sync/api.ts
+++ b/packages/typescript/src/api/sync/api.ts
@@ -216,54 +216,17 @@ export interface TranspileOutput {
     sourceMapText?: string;
 }
 
-const diagnosticOrigin = globalThis.Symbol("diagnosticOrigin");
-
-interface DiagnosticOrigin {
-    readonly snapshot: number;
-    readonly project: Path;
-}
-
-interface DiagnosticWithOrigin extends Diagnostic {
-    readonly [diagnosticOrigin]?: DiagnosticOrigin;
-}
-
 interface FormatDiagnosticRequest extends Diagnostic {
-    readonly originSnapshot: number;
-    readonly originProject: Path;
     readonly displayFileName?: string;
 }
 
-function associateDiagnostics(
-    diagnostics: readonly Diagnostic[],
-    origin: DiagnosticOrigin,
-): readonly Diagnostic[] {
-    for (const diagnostic of diagnostics) {
-        Object.defineProperty(diagnostic, diagnosticOrigin, { value: origin });
-        if (diagnostic.messageChain) {
-            associateDiagnostics(diagnostic.messageChain, origin);
-        }
-        if (diagnostic.relatedInformation) {
-            associateDiagnostics(diagnostic.relatedInformation, origin);
-        }
-    }
-    return diagnostics;
-}
-
 function toFormatDiagnosticRequest(
     diagnostic: Diagnostic,
-    expectedOrigin: DiagnosticOrigin,
     host: FormatDiagnosticsHost,
 ): FormatDiagnosticRequest {
-    const origin = (diagnostic as DiagnosticWithOrigin)[diagnosticOrigin];
-    if (origin?.snapshot !== expectedOrigin.snapshot || origin.project !== expectedOrigin.project) {
-        throw new Error("Diagnostic was not produced by this program.");
-    }
-
     const { messageChain, relatedInformation, ...diagnosticData } = diagnostic;
     return {
         ...diagnosticData,
-        originSnapshot: origin.snapshot,
-        originProject: origin.project,
         ...(diagnostic.fileName
             ? {
                 displayFileName: convertToRelativePath(
@@ -274,10 +237,10 @@ function toFormatDiagnosticRequest(
             }
             : {}),
         ...(messageChain
-            ? { messageChain: messageChain.map(d => toFormatDiagnosticRequest(d, expectedOrigin, host)) }
+            ? { messageChain: messageChain.map(d => toFormatDiagnosticRequest(d, host)) }
             : {}),
         ...(relatedInformation
-            ? { relatedInformation: relatedInformation.map(d => toFormatDiagnosticRequest(d, expectedOrigin, host)) }
+            ? { relatedInformation: relatedInformation.map(d => toFormatDiagnosticRequest(d, host)) }
             : {}),
     };
 }
@@ -1046,13 +1009,6 @@ export class Program {
         this.toPath = toPath;
     }
 
-    private associateDiagnostics(diagnostics: readonly Diagnostic[]): readonly Diagnostic[] {
-        return associateDiagnostics(diagnostics, {
-            snapshot: this.snapshotId,
-            project: this.project.id,
-        });
-    }
-
     getCompilerOptions(): CompilerOptions {
         return this.project.compilerOptions;
     }
@@ -1189,7 +1145,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return this.associateDiagnostics(data ?? []);
+        return data ?? [];
     }
 
     /**
@@ -1205,7 +1161,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return this.associateDiagnostics(data ?? []);
+        return data ?? [];
     }
 
     /**
@@ -1221,7 +1177,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return this.associateDiagnostics(data ?? []);
+        return data ?? [];
     }
 
     /**
@@ -1237,7 +1193,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return this.associateDiagnostics(data ?? []);
+        return data ?? [];
     }
 
     /**
@@ -1253,7 +1209,7 @@ export class Program {
             project: this.project.id,
             ...(files !== undefined ? { files } : {}),
         });
-        return this.associateDiagnostics(data ?? []);
+        return data ?? [];
     }
 
     /**
@@ -1264,7 +1220,7 @@ export class Program {
             snapshot: this.snapshotId,
             project: this.project.id,
         });
-        return this.associateDiagnostics(data ?? []);
+        return data ?? [];
     }
 
     /**
@@ -1275,7 +1231,7 @@ export class Program {
             snapshot: this.snapshotId,
             project: this.project.id,
         });
-        return this.associateDiagnostics(data ?? []);
+        return data ?? [];
     }
 
     /**
@@ -1286,7 +1242,7 @@ export class Program {
             snapshot: this.snapshotId,
             project: this.project.id,
         });
-        return this.associateDiagnostics(data ?? []);
+        return data ?? [];
     }
 
     /**
@@ -1296,11 +1252,10 @@ export class Program {
         diagnostics: readonly Diagnostic[],
         host: FormatDiagnosticsHost,
     ): string {
-        const origin = { snapshot: this.snapshotId, project: this.project.id };
         const data = this.client.apiRequest("formatDiagnostics", {
             snapshot: this.snapshotId,
             project: this.project.id,
-            diagnostics: diagnostics.map(d => toFormatDiagnosticRequest(d, origin, host)),
+            diagnostics: diagnostics.map(d => toFormatDiagnosticRequest(d, host)),
             newLine: host.getNewLine(),
         });
         return data.output;
@@ -1313,11 +1268,10 @@ export class Program {
         diagnostics: readonly Diagnostic[],
         host: FormatDiagnosticsHost,
     ): string {
-        const origin = { snapshot: this.snapshotId, project: this.project.id };
         const data = this.client.apiRequest("formatDiagnosticsWithColorAndContext", {
             snapshot: this.snapshotId,
             project: this.project.id,
-            diagnostics: diagnostics.map(d => toFormatDiagnosticRequest(d, origin, host)),
+            diagnostics: diagnostics.map(d => toFormatDiagnosticRequest(d, host)),
             newLine: host.getNewLine(),
         });
         return data.output;
@@ -1337,7 +1291,7 @@ export class Program {
         });
         return {
             emitSkipped: response.emitSkipped,
-            diagnostics: this.associateDiagnostics(response.diagnostics),
+            diagnostics: response.diagnostics,
             emittedFiles: response.emittedFiles,
         };
     }
@@ -1351,7 +1305,7 @@ export class Program {
             project: this.project.id,
             ...(emitOnly !== undefined ? { emitOnly } : {}),
         });
-        return toEmitOutput(response, this.associateDiagnostics(response.diagnostics));
+        return toEmitOutput(response, response.diagnostics);
     }
 
     /**
@@ -1363,7 +1317,7 @@ export class Program {
             project: this.project.id,
             files,
         });
-        return toEmitOutput(response, this.associateDiagnostics(response.diagnostics));
+        return toEmitOutput(response, response.diagnostics);
     }
 
     /**
@@ -1375,7 +1329,7 @@ export class Program {
             project: this.project.id,
             files,
         });
-        return toEmitOutput(response, this.associateDiagnostics(response.diagnostics));
+        return toEmitOutput(response, response.diagnostics);
     }
 }
 
diff --git a/packages/typescript/test/async/api.test.ts b/packages/typescript/test/async/api.test.ts
index 32840b3f50fd5..9a7d7c9bfbfe2 100644
--- a/packages/typescript/test/async/api.test.ts
+++ b/packages/typescript/test/async/api.test.ts
@@ -5684,7 +5684,8 @@ describe("Program - diagnostics", () => {
             const snapshot = await api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = await project.program.getSyntacticDiagnostics("/src/index.ts");
-            assert.deepEqual(diags, [{
+            assert.match(diags[0].sourceFileHash!, /^[0-9a-f]{32}$/);
+            assert.deepEqual(withoutSourceFileHashes(diags), [{
                 fileName: "/src/index.ts",
                 ...rangeOf(source, "="),
                 code: 1110,
@@ -5709,7 +5710,7 @@ describe("Program - diagnostics", () => {
             const diags = await project.program.getSemanticDiagnostics("/src/index.ts");
             const declRange = rangeOf(source, "callback", 0);
             const assignRange = rangeOf(source, "callback", 1);
-            assert.deepEqual(diags, [{
+            assert.deepEqual(withoutSourceFileHashes(diags), [{
                 fileName: "/src/index.ts",
                 ...assignRange,
                 code: 2322,
@@ -5753,7 +5754,7 @@ describe("Program - diagnostics", () => {
             const snapshot = await api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = await project.program.getSuggestionDiagnostics("/src/index.ts");
-            assert.deepEqual(diags, [{
+            assert.deepEqual(withoutSourceFileHashes(diags), [{
                 fileName: "/src/index.ts",
                 ...rangeOf(source, "_unused"),
                 code: 6133,
@@ -5777,7 +5778,7 @@ describe("Program - diagnostics", () => {
             const snapshot = await api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = await project.program.getConfigFileParsingDiagnostics();
-            assert.deepEqual(diags, [{
+            assert.deepEqual(withoutSourceFileHashes(diags), [{
                 fileName: "/tsconfig.json",
                 ...rangeOf(config, `"invalid"`),
                 code: 6046,
@@ -5854,30 +5855,29 @@ describe("Program - diagnostics", () => {
         }
     });
 
-    test("formatDiagnostics rejects diagnostics from another program", async () => {
+    test("formatDiagnostics rejects diagnostics for stale source text", async () => {
         const api = spawnAPI({
-            "/a/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
-            "/a/index.ts": `const x: number = "oops";`,
-            "/b/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
-            "/b/index.ts": `export const x = 1;`,
+            "/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+            "/index.ts": `const x: number = "oops";`,
         });
         try {
-            const snapshot = await api.updateSnapshot({
-                openProjects: ["/a/tsconfig.json", "/b/tsconfig.json"],
-            });
-            const a = snapshot.getProject("/a/tsconfig.json")!.program;
-            const b = snapshot.getProject("/b/tsconfig.json")!.program;
-            const diagnostics = await a.getSemanticDiagnostics("/a/index.ts");
+            const snapshot = await api.updateSnapshot({ openProject: "/tsconfig.json" });
+            const program = snapshot.getProject("/tsconfig.json")!.program;
+            const diagnostics = await program.getSemanticDiagnostics("/index.ts");
             const host = {
                 getCurrentDirectory: () => "/",
                 getCanonicalFileName: (fileName: string) => fileName,
                 getNewLine: () => "\n",
             };
+            const staleDiagnostics = diagnostics.map(diagnostic => ({
+                ...diagnostic,
+                sourceFileHash: "00000000000000000000000000000000",
+            }));
 
             // @sync: assert.throws(() =>
             await assert.rejects( // @sync-skip
-                b.formatDiagnostics(diagnostics, host),
-                /Diagnostic was not produced by this program/,
+                program.formatDiagnostics(staleDiagnostics, host),
+                /source file content has changed/,
             );
         }
         finally {
@@ -5885,33 +5885,32 @@ describe("Program - diagnostics", () => {
         }
     });
 
-    test("formatDiagnostics rejects diagnostics without origin metadata", async () => {
+    test("formatDiagnostics accepts cloned diagnostics and parseConfigFile diagnostics", async () => {
+        const configText = `{ "compilerOptions": { "target": "invalid" } }`;
         const api = spawnAPI({
-            "/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+            "/tsconfig.json": configText,
             "/src/index.ts": `const x: number = "oops";`,
         });
         try {
             const snapshot = await api.updateSnapshot({ openProject: "/tsconfig.json" });
             const program = snapshot.getProject("/tsconfig.json")!.program;
             const diagnostics = await program.getSemanticDiagnostics("/src/index.ts");
+            const configDiagnostics = (await api.parseConfigFile("/tsconfig.json")).errors;
             const host = {
                 getCurrentDirectory: () => "/",
                 getCanonicalFileName: (fileName: string) => fileName,
                 getNewLine: () => "\n",
             };
-            const diagnosticsWithoutOrigin = [
+            const clonedDiagnostics = [
                 [{ ...diagnostics[0] }],
                 structuredClone(diagnostics),
                 JSON.parse(JSON.stringify(diagnostics)),
             ];
 
-            for (const clonedDiagnostics of diagnosticsWithoutOrigin) {
-                // @sync: assert.throws(() =>
-                await assert.rejects( // @sync-skip
-                    program.formatDiagnostics(clonedDiagnostics, host),
-                    /Diagnostic was not produced by this program/,
-                );
+            for (const cloned of clonedDiagnostics) {
+                assert.ok((await program.formatDiagnostics(cloned, host)).includes("TS2322"));
             }
+            assert.ok((await program.formatDiagnosticsWithColorAndContext(configDiagnostics, host)).includes(configText));
         }
         finally {
             await api.close();
@@ -5976,7 +5975,7 @@ describe("Program - diagnostics", () => {
             const snapshot = await api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = await project.program.getBindDiagnostics("/src/index.ts");
-            assert.deepEqual(diags, [
+            assert.deepEqual(withoutSourceFileHashes(diags), [
                 {
                     fileName: "/src/index.ts",
                     ...rangeOf(source, "x", 0),
@@ -6008,7 +6007,7 @@ describe("Program - diagnostics", () => {
             const snapshot = await api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = await project.program.getProgramDiagnostics();
-            assert.deepEqual(diags, [
+            assert.deepEqual(withoutSourceFileHashes(diags), [
                 {
                     fileName: "/tsconfig.json",
                     ...rangeOf(config, `"bundler"`),
@@ -6086,7 +6085,7 @@ describe("Program - diagnostics", () => {
             const snapshot = await api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = await project.program.getSyntacticDiagnostics(["/src/a.ts", "/src/b.ts"]);
-            assert.deepEqual(diags, [
+            assert.deepEqual(withoutSourceFileHashes(diags), [
                 {
                     fileName: "/src/a.ts",
                     ...rangeOf(sourceA, "="),
@@ -6866,6 +6865,10 @@ function rangeOf(source: string, searchString: string, occurrence: number = 0):
     return { pos: index, end: index + searchString.length };
 }
 
+function withoutSourceFileHashes<T>(value: T): T {
+    return JSON.parse(JSON.stringify(value, (key, item) => key === "sourceFileHash" ? undefined : item)) as T;
+}
+
 function applyTextEdits(source: string, edits: readonly TextEdit[]): string {
     const sorted = [...edits].sort((a, b) => b.pos - a.pos);
     let result = source;
diff --git a/packages/typescript/test/sync/api.test.ts b/packages/typescript/test/sync/api.test.ts
index 7bdc46712eaa6..b624ee2bc5f3b 100644
--- a/packages/typescript/test/sync/api.test.ts
+++ b/packages/typescript/test/sync/api.test.ts
@@ -5692,7 +5692,8 @@ describe("Program - diagnostics", () => {
             const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = project.program.getSyntacticDiagnostics("/src/index.ts");
-            assert.deepEqual(diags, [{
+            assert.match(diags[0].sourceFileHash!, /^[0-9a-f]{32}$/);
+            assert.deepEqual(withoutSourceFileHashes(diags), [{
                 fileName: "/src/index.ts",
                 ...rangeOf(source, "="),
                 code: 1110,
@@ -5717,7 +5718,7 @@ describe("Program - diagnostics", () => {
             const diags = project.program.getSemanticDiagnostics("/src/index.ts");
             const declRange = rangeOf(source, "callback", 0);
             const assignRange = rangeOf(source, "callback", 1);
-            assert.deepEqual(diags, [{
+            assert.deepEqual(withoutSourceFileHashes(diags), [{
                 fileName: "/src/index.ts",
                 ...assignRange,
                 code: 2322,
@@ -5761,7 +5762,7 @@ describe("Program - diagnostics", () => {
             const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = project.program.getSuggestionDiagnostics("/src/index.ts");
-            assert.deepEqual(diags, [{
+            assert.deepEqual(withoutSourceFileHashes(diags), [{
                 fileName: "/src/index.ts",
                 ...rangeOf(source, "_unused"),
                 code: 6133,
@@ -5785,7 +5786,7 @@ describe("Program - diagnostics", () => {
             const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = project.program.getConfigFileParsingDiagnostics();
-            assert.deepEqual(diags, [{
+            assert.deepEqual(withoutSourceFileHashes(diags), [{
                 fileName: "/tsconfig.json",
                 ...rangeOf(config, `"invalid"`),
                 code: 6046,
@@ -5862,56 +5863,58 @@ describe("Program - diagnostics", () => {
         }
     });
 
-    test("formatDiagnostics rejects diagnostics from another program", () => {
+    test("formatDiagnostics rejects diagnostics for stale source text", () => {
         const api = spawnAPI({
-            "/a/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
-            "/a/index.ts": `const x: number = "oops";`,
-            "/b/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
-            "/b/index.ts": `export const x = 1;`,
+            "/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+            "/index.ts": `const x: number = "oops";`,
         });
         try {
-            const snapshot = api.updateSnapshot({
-                openProjects: ["/a/tsconfig.json", "/b/tsconfig.json"],
-            });
-            const a = snapshot.getProject("/a/tsconfig.json")!.program;
-            const b = snapshot.getProject("/b/tsconfig.json")!.program;
-            const diagnostics = a.getSemanticDiagnostics("/a/index.ts");
+            const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
+            const program = snapshot.getProject("/tsconfig.json")!.program;
+            const diagnostics = program.getSemanticDiagnostics("/index.ts");
             const host = {
                 getCurrentDirectory: () => "/",
                 getCanonicalFileName: (fileName: string) => fileName,
                 getNewLine: () => "\n",
             };
+            const staleDiagnostics = diagnostics.map(diagnostic => ({
+                ...diagnostic,
+                sourceFileHash: "00000000000000000000000000000000",
+            }));
 
-            assert.throws(() => b.formatDiagnostics(diagnostics, host), /Diagnostic was not produced by this program/);
+            assert.throws(() => program.formatDiagnostics(staleDiagnostics, host), /source file content has changed/);
         }
         finally {
             api.close();
         }
     });
 
-    test("formatDiagnostics rejects diagnostics without origin metadata", () => {
+    test("formatDiagnostics accepts cloned diagnostics and parseConfigFile diagnostics", () => {
+        const configText = `{ "compilerOptions": { "target": "invalid" } }`;
         const api = spawnAPI({
-            "/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
+            "/tsconfig.json": configText,
             "/src/index.ts": `const x: number = "oops";`,
         });
         try {
             const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
             const program = snapshot.getProject("/tsconfig.json")!.program;
             const diagnostics = program.getSemanticDiagnostics("/src/index.ts");
+            const configDiagnostics = api.parseConfigFile("/tsconfig.json").errors;
             const host = {
                 getCurrentDirectory: () => "/",
                 getCanonicalFileName: (fileName: string) => fileName,
                 getNewLine: () => "\n",
             };
-            const diagnosticsWithoutOrigin = [
+            const clonedDiagnostics = [
                 [{ ...diagnostics[0] }],
                 structuredClone(diagnostics),
                 JSON.parse(JSON.stringify(diagnostics)),
             ];
 
-            for (const clonedDiagnostics of diagnosticsWithoutOrigin) {
-                assert.throws(() => program.formatDiagnostics(clonedDiagnostics, host), /Diagnostic was not produced by this program/);
+            for (const cloned of clonedDiagnostics) {
+                assert.ok(program.formatDiagnostics(cloned, host).includes("TS2322"));
             }
+            assert.ok(program.formatDiagnosticsWithColorAndContext(configDiagnostics, host).includes(configText));
         }
         finally {
             api.close();
@@ -5976,7 +5979,7 @@ describe("Program - diagnostics", () => {
             const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = project.program.getBindDiagnostics("/src/index.ts");
-            assert.deepEqual(diags, [
+            assert.deepEqual(withoutSourceFileHashes(diags), [
                 {
                     fileName: "/src/index.ts",
                     ...rangeOf(source, "x", 0),
@@ -6008,7 +6011,7 @@ describe("Program - diagnostics", () => {
             const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = project.program.getProgramDiagnostics();
-            assert.deepEqual(diags, [
+            assert.deepEqual(withoutSourceFileHashes(diags), [
                 {
                     fileName: "/tsconfig.json",
                     ...rangeOf(config, `"bundler"`),
@@ -6086,7 +6089,7 @@ describe("Program - diagnostics", () => {
             const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = project.program.getSyntacticDiagnostics(["/src/a.ts", "/src/b.ts"]);
-            assert.deepEqual(diags, [
+            assert.deepEqual(withoutSourceFileHashes(diags), [
                 {
                     fileName: "/src/a.ts",
                     ...rangeOf(sourceA, "="),
@@ -6843,6 +6846,10 @@ function rangeOf(source: string, searchString: string, occurrence: number = 0):
     return { pos: index, end: index + searchString.length };
 }
 
+function withoutSourceFileHashes<T>(value: T): T {
+    return JSON.parse(JSON.stringify(value, (key, item) => key === "sourceFileHash" ? undefined : item)) as T;
+}
+
 function applyTextEdits(source: string, edits: readonly TextEdit[]): string {
     const sorted = [...edits].sort((a, b) => b.pos - a.pos);
     let result = source;
diff --git a/tsc/internal/api/format_diagnostics.go b/tsc/internal/api/format_diagnostics.go
index 4f735a4a7a2bc..56e2d02a2982e 100644
--- a/tsc/internal/api/format_diagnostics.go
+++ b/tsc/internal/api/format_diagnostics.go
@@ -29,7 +29,7 @@ func (s *Session) handleFormatDiagnostics(ctx context.Context, params *FormatDia
 	resolver := newFormatFileResolver(sd, program)
 	diags := make([]diagnosticwriter.Diagnostic, len(params.Diagnostics))
 	for i, d := range params.Diagnostics {
-		diag, err := newWireDiagnostic(d, resolver, params.Snapshot, params.Project)
+		diag, err := newWireDiagnostic(d, resolver)
 		if err != nil {
 			return nil, err
 		}
@@ -124,17 +124,14 @@ type wireDiagnostic struct {
 func newWireDiagnostic(
 	resp *DiagnosticResponse,
 	resolver *formatFileResolver,
-	snapshot SnapshotID,
-	project ProjectID,
 ) (*wireDiagnostic, error) {
-	if resp.OriginSnapshot != snapshot || resp.OriginProject != project {
-		return nil, fmt.Errorf("%w: diagnostic was not produced by this program", ErrClientError)
-	}
-
 	sourceFile := resolver.resolve(resp.FileName)
 	if resp.FileName != "" && sourceFile == nil {
 		return nil, fmt.Errorf("%w: diagnostic source file not found: %s", ErrClientError, resp.FileName)
 	}
+	if sourceFile != nil && sourceFileHash(sourceFile) != resp.SourceFileHash {
+		return nil, fmt.Errorf("%w: diagnostic source file content has changed: %s", ErrClientError, resp.FileName)
+	}
 
 	pos, end := resp.Pos, resp.End
 	var file diagnosticwriter.FileLike
@@ -159,7 +156,7 @@ func newWireDiagnostic(
 	if len(resp.MessageChain) > 0 {
 		wd.chain = make([]diagnosticwriter.Diagnostic, len(resp.MessageChain))
 		for i, c := range resp.MessageChain {
-			diag, err := newWireDiagnostic(c, resolver, snapshot, project)
+			diag, err := newWireDiagnostic(c, resolver)
 			if err != nil {
 				return nil, err
 			}
@@ -169,7 +166,7 @@ func newWireDiagnostic(
 	if len(resp.RelatedInformation) > 0 {
 		wd.related = make([]diagnosticwriter.Diagnostic, len(resp.RelatedInformation))
 		for i, ri := range resp.RelatedInformation {
-			diag, err := newWireDiagnostic(ri, resolver, snapshot, project)
+			diag, err := newWireDiagnostic(ri, resolver)
 			if err != nil {
 				return nil, err
 			}
diff --git a/tsc/internal/api/proto.go b/tsc/internal/api/proto.go
index fbf7ce7ef3250..ce090dca07ebe 100644
--- a/tsc/internal/api/proto.go
+++ b/tsc/internal/api/proto.go
@@ -20,6 +20,7 @@ import (
 	"github.com/microsoft/TypeScript/tsc/internal/project"
 	"github.com/microsoft/TypeScript/tsc/internal/tsoptions"
 	"github.com/microsoft/TypeScript/tsc/internal/tspath"
+	"github.com/zeebo/xxh3"
 )
 
 var (
@@ -1419,6 +1420,8 @@ type GetProjectDiagnosticsParams struct {
 type DiagnosticResponse struct {
 	// FileName is the path of the file this diagnostic belongs to, if any.
 	FileName string `json:"fileName,omitempty"`
+	// SourceFileHash identifies the source text used to produce this diagnostic.
+	SourceFileHash string `json:"sourceFileHash,omitempty"`
 	// Pos is the start position of the diagnostic in the source file.
 	Pos int `json:"pos"`
 	// End is the end position of the diagnostic in the source file.
@@ -1439,13 +1442,18 @@ type DiagnosticResponse struct {
 	MessageChain []*DiagnosticResponse `json:"messageChain,omitempty"`
 	// RelatedInformation contains related diagnostic information, if any.
 	RelatedInformation []*DiagnosticResponse `json:"relatedInformation,omitempty"`
-	// OriginSnapshot and OriginProject identify the program that produced this diagnostic.
-	OriginSnapshot SnapshotID `json:"originSnapshot,omitzero"`
-	OriginProject  ProjectID  `json:"originProject,omitzero"`
 	// DisplayFileName is the host-formatted file name used only for diagnostic output.
 	DisplayFileName string `json:"displayFileName,omitempty"`
 }
 
+func sourceFileHash(file *ast.SourceFile) string {
+	hash := file.Hash
+	if hash == (xxh3.Uint128{}) {
+		hash = xxh3.Hash128([]byte(file.Text()))
+	}
+	return fmt.Sprintf("%016x%016x", hash.Hi, hash.Lo)
+}
+
 // NewDiagnosticResponse converts an ast.Diagnostic to a DiagnosticResponse.
 func NewDiagnosticResponse(d *ast.Diagnostic) *DiagnosticResponse {
 	pos := d.Pos()
@@ -1469,6 +1477,7 @@ func NewDiagnosticResponse(d *ast.Diagnostic) *DiagnosticResponse {
 
 	if file != nil {
 		resp.FileName = file.FileName()
+		resp.SourceFileHash = sourceFileHash(file)
 	}
 
 	if chain := d.MessageChain(); len(chain) > 0 {
diff --git a/tsc/internal/api/proto_test.go b/tsc/internal/api/proto_test.go
index 34c9dcc13fd39..32bbd8c9e6536 100644
--- a/tsc/internal/api/proto_test.go
+++ b/tsc/internal/api/proto_test.go
@@ -76,6 +76,7 @@ func TestNewDiagnosticResponseUsesUTF16Offsets(t *testing.T) {
 	diag := ast.NewDiagnostic(file, core.NewTextRange(pos, end), diagnostics.Expression_expected)
 	resp := api.NewDiagnosticResponse(diag)
 
+	assert.Equal(t, len(resp.SourceFileHash), 32)
 	assert.Equal(t, resp.Pos, 9)
 	assert.Equal(t, resp.End, 10)
 	assert.Equal(t, resp.Pos, file.GetPositionMap().UTF8ToUTF16(pos))
diff --git a/tsc/internal/api/session_format_diagnostics_test.go b/tsc/internal/api/session_format_diagnostics_test.go
index 3bea9603f9568..e3bdd0c7be019 100644
--- a/tsc/internal/api/session_format_diagnostics_test.go
+++ b/tsc/internal/api/session_format_diagnostics_test.go
@@ -2,15 +2,22 @@ package api
 
 import (
 	"context"
+	"fmt"
 	"strings"
 	"testing"
 
 	"github.com/microsoft/TypeScript/tsc/internal/bundled"
 	"github.com/microsoft/TypeScript/tsc/internal/diagnostics"
 	"github.com/microsoft/TypeScript/tsc/internal/testutil/projecttestutil"
+	"github.com/zeebo/xxh3"
 	"gotest.tools/v3/assert"
 )
 
+func sourceFileHashForText(text string) string {
+	hash := xxh3.Hash128([]byte(text))
+	return fmt.Sprintf("%016x%016x", hash.Hi, hash.Lo)
+}
+
 func setupFormatSession(t *testing.T, files map[string]any, mainFile string) (*Session, SnapshotID, ProjectID) {
 	t.Helper()
 	projectSession, _ := projecttestutil.Setup(files)
@@ -33,16 +40,6 @@ func setupFormatSession(t *testing.T, files map[string]any, mainFile string) (*S
 }
 
 func formatDiagnosticsParams(snapshot SnapshotID, project ProjectID, diagnostics []*DiagnosticResponse) *FormatDiagnosticsParams {
-	var setOrigin func([]*DiagnosticResponse)
-	setOrigin = func(diags []*DiagnosticResponse) {
-		for _, diag := range diags {
-			diag.OriginSnapshot = snapshot
-			diag.OriginProject = project
-			setOrigin(diag.MessageChain)
-			setOrigin(diag.RelatedInformation)
-		}
-	}
-	setOrigin(diagnostics)
 	return &FormatDiagnosticsParams{
 		Snapshot:    snapshot,
 		Project:     project,
@@ -201,12 +198,13 @@ func TestFormatDiagnosticsClampsOutOfRangePositions(t *testing.T) {
 	ctx := context.Background()
 
 	stale := []*DiagnosticResponse{{
-		FileName: fileName,
-		Pos:      100_000,
-		End:      200_000,
-		Code:     1234,
-		Category: diagnostics.CategoryError,
-		Text:     "Stale diagnostic.",
+		FileName:       fileName,
+		SourceFileHash: sourceFileHashForText("export const x = 1;\n"),
+		Pos:            100_000,
+		End:            200_000,
+		Code:           1234,
+		Category:       diagnostics.CategoryError,
+		Text:           "Stale diagnostic.",
 	}}
 
 	plain, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, stale), false)
@@ -220,7 +218,7 @@ func TestFormatDiagnosticsClampsOutOfRangePositions(t *testing.T) {
 	assert.Assert(t, strings.Contains(color.Output, "Stale diagnostic."))
 }
 
-func TestFormatDiagnosticsRejectsMismatchedOrMissingSources(t *testing.T) {
+func TestFormatDiagnosticsRejectsStaleOrMissingSources(t *testing.T) {
 	t.Parallel()
 	if !bundled.Embedded {
 		t.Skip("bundled files are not embedded")
@@ -233,14 +231,15 @@ func TestFormatDiagnosticsRejectsMismatchedOrMissingSources(t *testing.T) {
 	}, fileName)
 	ctx := context.Background()
 
-	mismatched := formatDiagnosticsParams(snapshot, project, []*DiagnosticResponse{{
-		Code:     1234,
-		Category: diagnostics.CategoryError,
-		Text:     "Wrong program.",
+	stale := formatDiagnosticsParams(snapshot, project, []*DiagnosticResponse{{
+		FileName:       fileName,
+		SourceFileHash: sourceFileHashForText("different content"),
+		Code:           1234,
+		Category:       diagnostics.CategoryError,
+		Text:           "Stale diagnostic.",
 	}})
-	mismatched.Diagnostics[0].OriginSnapshot++
-	_, err := session.handleFormatDiagnostics(ctx, mismatched, false)
-	assert.ErrorContains(t, err, "diagnostic was not produced by this program")
+	_, err := session.handleFormatDiagnostics(ctx, stale, false)
+	assert.ErrorContains(t, err, "diagnostic source file content has changed")
 
 	missing := formatDiagnosticsParams(snapshot, project, []*DiagnosticResponse{{
 		FileName: "/home/projects/p/src/missing.ts",
diff --git a/tsc/internal/tsoptions/tsconfigparsing.go b/tsc/internal/tsoptions/tsconfigparsing.go
index 6f4db55f300fe..32e89b5070a5b 100644
--- a/tsc/internal/tsoptions/tsconfigparsing.go
+++ b/tsc/internal/tsoptions/tsconfigparsing.go
@@ -21,6 +21,7 @@ import (
 	"github.com/microsoft/TypeScript/tsc/internal/tspath"
 	"github.com/microsoft/TypeScript/tsc/internal/vfs"
 	"github.com/microsoft/TypeScript/tsc/internal/vfs/vfsmatch"
+	"github.com/zeebo/xxh3"
 )
 
 type extendsResult struct {
@@ -298,6 +299,7 @@ func NewTsconfigSourceFileFromFilePath(configFileName string, configPath tspath.
 		FileName: configFileName,
 		Path:     configPath,
 	}, configSourceText, core.ScriptKindJSON)
+	sourceFile.Hash = xxh3.Hash128([]byte(configSourceText))
 	return &TsConfigSourceFile{
 		SourceFile: sourceFile,
 	}

From 3c5feb4e88b7f663c649d130ed6ff5dd544dda32 Mon Sep 17 00:00:00 2001
From: John Favret <64748847+johnfav03@users.noreply.github.com>
Date: Fri, 21 Aug 2026 14:46:09 -0500
Subject: [PATCH 5/6] addressed feedback

---
 tsc/internal/api/format_diagnostics.go        |  2 +-
 .../api/session_format_diagnostics_test.go    | 19 +++++++++----------
 2 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/tsc/internal/api/format_diagnostics.go b/tsc/internal/api/format_diagnostics.go
index 56e2d02a2982e..88befd0fef292 100644
--- a/tsc/internal/api/format_diagnostics.go
+++ b/tsc/internal/api/format_diagnostics.go
@@ -129,7 +129,7 @@ func newWireDiagnostic(
 	if resp.FileName != "" && sourceFile == nil {
 		return nil, fmt.Errorf("%w: diagnostic source file not found: %s", ErrClientError, resp.FileName)
 	}
-	if sourceFile != nil && sourceFileHash(sourceFile) != resp.SourceFileHash {
+	if sourceFile != nil && resp.SourceFileHash != "" && sourceFileHash(sourceFile) != resp.SourceFileHash {
 		return nil, fmt.Errorf("%w: diagnostic source file content has changed: %s", ErrClientError, resp.FileName)
 	}
 
diff --git a/tsc/internal/api/session_format_diagnostics_test.go b/tsc/internal/api/session_format_diagnostics_test.go
index e3bdd0c7be019..c547f7b5242d8 100644
--- a/tsc/internal/api/session_format_diagnostics_test.go
+++ b/tsc/internal/api/session_format_diagnostics_test.go
@@ -184,7 +184,7 @@ func TestFormatDiagnosticsWithoutFile(t *testing.T) {
 		"\x1b[91merror\x1b[0m\x1b[90m TS1234: \x1b[0mSome global problem.\n\n    Additional context.\n")
 }
 
-func TestFormatDiagnosticsClampsOutOfRangePositions(t *testing.T) {
+func TestFormatDiagnosticsAllowsUnhashedDiagnosticsAndClampsOutOfRangePositions(t *testing.T) {
 	t.Parallel()
 	if !bundled.Embedded {
 		t.Skip("bundled files are not embedded")
@@ -198,24 +198,23 @@ func TestFormatDiagnosticsClampsOutOfRangePositions(t *testing.T) {
 	ctx := context.Background()
 
 	stale := []*DiagnosticResponse{{
-		FileName:       fileName,
-		SourceFileHash: sourceFileHashForText("export const x = 1;\n"),
-		Pos:            100_000,
-		End:            200_000,
-		Code:           1234,
-		Category:       diagnostics.CategoryError,
-		Text:           "Stale diagnostic.",
+		FileName: fileName,
+		Pos:      100_000,
+		End:      200_000,
+		Code:     1234,
+		Category: diagnostics.CategoryError,
+		Text:     "Manually constructed diagnostic.",
 	}}
 
 	plain, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, stale), false)
 	assert.NilError(t, err)
 	assert.Equal(t, plain.Output,
-		"home/projects/p/src/index.ts(2,1): error TS1234: Stale diagnostic.\n")
+		"home/projects/p/src/index.ts(2,1): error TS1234: Manually constructed diagnostic.\n")
 
 	color, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, stale), true)
 	assert.NilError(t, err)
 	assert.Assert(t, strings.Contains(color.Output, "TS1234: "))
-	assert.Assert(t, strings.Contains(color.Output, "Stale diagnostic."))
+	assert.Assert(t, strings.Contains(color.Output, "Manually constructed diagnostic."))
 }
 
 func TestFormatDiagnosticsRejectsStaleOrMissingSources(t *testing.T) {

From 9d62a929405533e9c31ab96594160938296c5cdf Mon Sep 17 00:00:00 2001
From: John Favret <64748847+johnfav03@users.noreply.github.com>
Date: Fri, 21 Aug 2026 16:45:38 -0500
Subject: [PATCH 6/6] move diagnostic formatting from go to js

---
 packages/typescript/src/api/async/api.ts      |  60 +--
 .../typescript/src/api/diagnosticFormatter.ts | 196 ++++++++++
 .../typescript/src/api/proto.generated.ts     |  36 +-
 packages/typescript/src/api/sync/api.ts       |  60 +--
 packages/typescript/test/async/api.test.ts    |  68 ++--
 packages/typescript/test/sync/api.test.ts     |  70 ++--
 tsc/internal/api/format_diagnostics.go        | 206 -----------
 tsc/internal/api/proto.go                     | 270 +++++++-------
 tsc/internal/api/proto_test.go                |  24 +-
 tsc/internal/api/session.go                   |   4 -
 .../api/session_format_diagnostics_test.go    | 344 ------------------
 .../diagnosticwriter/diagnosticwriter.go      |  42 ---
 tsc/internal/tsoptions/tsconfigparsing.go     |   2 -
 13 files changed, 461 insertions(+), 921 deletions(-)
 create mode 100644 packages/typescript/src/api/diagnosticFormatter.ts
 delete mode 100644 tsc/internal/api/format_diagnostics.go
 delete mode 100644 tsc/internal/api/session_format_diagnostics_test.go

diff --git a/packages/typescript/src/api/async/api.ts b/packages/typescript/src/api/async/api.ts
index 2c903c009d724..09ec61f37439a 100644
--- a/packages/typescript/src/api/async/api.ts
+++ b/packages/typescript/src/api/async/api.ts
@@ -27,6 +27,10 @@ import {
     unescapeLeadingUnderscores,
 } from "../../ast/index.ts";
 import { assertNever } from "../../internal/utils.ts";
+import {
+    formatDiagnostics,
+    formatDiagnosticsWithColorAndContext,
+} from "../diagnosticFormatter.ts";
 import {
     encodeNode,
     uint8ArrayToBase64,
@@ -45,7 +49,6 @@ import type {
     LSPConnectionOptions,
 } from "../options.ts";
 import {
-    convertToRelativePath,
     createGetCanonicalFileName,
     toPath,
 } from "../path.ts";
@@ -208,35 +211,6 @@ export interface TranspileOutput {
     sourceMapText?: string;
 }
 
-interface FormatDiagnosticRequest extends Diagnostic {
-    readonly displayFileName?: string;
-}
-
-function toFormatDiagnosticRequest(
-    diagnostic: Diagnostic,
-    host: FormatDiagnosticsHost,
-): FormatDiagnosticRequest {
-    const { messageChain, relatedInformation, ...diagnosticData } = diagnostic;
-    return {
-        ...diagnosticData,
-        ...(diagnostic.fileName
-            ? {
-                displayFileName: convertToRelativePath(
-                    diagnostic.fileName,
-                    host.getCurrentDirectory(),
-                    fileName => host.getCanonicalFileName(fileName),
-                ),
-            }
-            : {}),
-        ...(messageChain
-            ? { messageChain: messageChain.map(d => toFormatDiagnosticRequest(d, host)) }
-            : {}),
-        ...(relatedInformation
-            ? { relatedInformation: relatedInformation.map(d => toFormatDiagnosticRequest(d, host)) }
-            : {}),
-    };
-}
-
 export class API<FromLSP extends boolean = false> {
     private client: Client;
     private sourceFileCache: SourceFileCache;
@@ -1244,13 +1218,7 @@ export class Program {
         diagnostics: readonly Diagnostic[],
         host: FormatDiagnosticsHost,
     ): Promise<string> {
-        const data = await this.client.apiRequest("formatDiagnostics", {
-            snapshot: this.snapshotId,
-            project: this.project.id,
-            diagnostics: diagnostics.map(d => toFormatDiagnosticRequest(d, host)),
-            newLine: host.getNewLine(),
-        });
-        return data.output;
+        return formatDiagnostics(diagnostics, host);
     }
 
     /**
@@ -1260,13 +1228,7 @@ export class Program {
         diagnostics: readonly Diagnostic[],
         host: FormatDiagnosticsHost,
     ): Promise<string> {
-        const data = await this.client.apiRequest("formatDiagnosticsWithColorAndContext", {
-            snapshot: this.snapshotId,
-            project: this.project.id,
-            diagnostics: diagnostics.map(d => toFormatDiagnosticRequest(d, host)),
-            newLine: host.getNewLine(),
-        });
-        return data.output;
+        return formatDiagnosticsWithColorAndContext(diagnostics, host);
     }
 
     /**
@@ -1297,7 +1259,7 @@ export class Program {
             project: this.project.id,
             ...(emitOnly !== undefined ? { emitOnly } : {}),
         });
-        return toEmitOutput(response, response.diagnostics);
+        return toEmitOutput(response);
     }
 
     /**
@@ -1309,7 +1271,7 @@ export class Program {
             project: this.project.id,
             files,
         });
-        return toEmitOutput(response, response.diagnostics);
+        return toEmitOutput(response);
     }
 
     /**
@@ -1321,18 +1283,18 @@ export class Program {
             project: this.project.id,
             files,
         });
-        return toEmitOutput(response, response.diagnostics);
+        return toEmitOutput(response);
     }
 }
 
-function toEmitOutput(response: ProtocolEmitOutputResponse, diagnostics: readonly Diagnostic[]): EmitOutput {
+function toEmitOutput(response: ProtocolEmitOutputResponse): EmitOutput {
     const outputFiles = new Map<string, EmitOutputFile>();
     for (const { fileName, ...outputFile } of response.outputFiles) {
         outputFiles.set(fileName, outputFile);
     }
     return {
         emitSkipped: response.emitSkipped,
-        diagnostics,
+        diagnostics: response.diagnostics,
         outputFiles,
     };
 }
diff --git a/packages/typescript/src/api/diagnosticFormatter.ts b/packages/typescript/src/api/diagnosticFormatter.ts
new file mode 100644
index 0000000000000..905b7d04a539a
--- /dev/null
+++ b/packages/typescript/src/api/diagnosticFormatter.ts
@@ -0,0 +1,196 @@
+import { convertToRelativePath } from "./path.ts";
+import type { DiagnosticResponse as Diagnostic } from "./proto.generated.ts";
+
+export interface FormatDiagnosticsHost {
+    getCurrentDirectory(): string;
+    getCanonicalFileName(fileName: string): string;
+    getNewLine(): string;
+}
+
+const foregroundColorEscapeGrey = "\x1b[90m";
+const foregroundColorEscapeRed = "\x1b[91m";
+const foregroundColorEscapeYellow = "\x1b[93m";
+const foregroundColorEscapeBlue = "\x1b[94m";
+const foregroundColorEscapeCyan = "\x1b[96m";
+const gutterStyleSequence = "\x1b[7m";
+const gutterSeparator = " ";
+const resetEscapeSequence = "\x1b[0m";
+const ellipsis = "...";
+const halfIndent = "  ";
+const indent = "    ";
+const fileAppearsToBeBinaryCode = 1490;
+
+function diagnosticCategoryName(category: number): string {
+    switch (category) {
+        case 0:
+            return "warning";
+        case 1:
+            return "error";
+        case 2:
+            return "suggestion";
+        case 3:
+            return "message";
+        default:
+            throw new Error(`Unknown diagnostic category: ${category}`);
+    }
+}
+
+function getCategoryFormat(category: number): string {
+    switch (category) {
+        case 0:
+            return foregroundColorEscapeYellow;
+        case 1:
+            return foregroundColorEscapeRed;
+        case 2:
+            return foregroundColorEscapeGrey;
+        case 3:
+            return foregroundColorEscapeBlue;
+        default:
+            throw new Error(`Unknown diagnostic category: ${category}`);
+    }
+}
+
+function formatColorAndReset(text: string, formatStyle: string): string {
+    return formatStyle + text + resetEscapeSequence;
+}
+
+function diagnosticPrefix(diagnostic: Diagnostic): string {
+    return diagnostic.source || "TS";
+}
+
+function flattenDiagnosticMessage(diagnostic: Diagnostic, newLine: string, indentLevel = 0): string {
+    let result = "";
+    if (indentLevel) {
+        result += newLine + "  ".repeat(indentLevel);
+    }
+    result += diagnostic.text;
+    for (const child of diagnostic.messageChain ?? []) {
+        result += flattenDiagnosticMessage(child, newLine, indentLevel + 1);
+    }
+    return result;
+}
+
+function relativeFileName(fileName: string, host: FormatDiagnosticsHost): string {
+    return convertToRelativePath(
+        fileName,
+        host.getCurrentDirectory(),
+        name => host.getCanonicalFileName(name),
+    );
+}
+
+function formatLocation(diagnostic: Diagnostic, host: FormatDiagnosticsHost): string {
+    if (!diagnostic.fileName || !diagnostic.startPosition) return "";
+    const fileName = relativeFileName(diagnostic.fileName, host);
+    const { line, character } = diagnostic.startPosition;
+    return formatColorAndReset(fileName, foregroundColorEscapeCyan) +
+        ":" +
+        formatColorAndReset(`${line + 1}`, foregroundColorEscapeYellow) +
+        ":" +
+        formatColorAndReset(`${character + 1}`, foregroundColorEscapeYellow);
+}
+
+function formatCodeSpan(
+    diagnostic: Diagnostic,
+    lineIndent: string,
+    squiggleColor: string,
+    host: FormatDiagnosticsHost,
+): string {
+    const { startPosition, endPosition, sourceLines } = diagnostic;
+    if (!startPosition || !endPosition || !sourceLines?.length) return "";
+
+    const hasMoreThanFiveLines = endPosition.line - startPosition.line >= 4;
+    const gutterWidth = hasMoreThanFiveLines
+        ? Math.max(ellipsis.length, `${endPosition.line + 1}`.length)
+        : `${endPosition.line + 1}`.length;
+    let context = "";
+    let previousLine: number | undefined;
+
+    for (const sourceLine of sourceLines) {
+        if (previousLine !== undefined && sourceLine.line > previousLine + 1) {
+            context += host.getNewLine();
+            context += lineIndent +
+                formatColorAndReset(ellipsis.padStart(gutterWidth), gutterStyleSequence) +
+                gutterSeparator;
+        }
+
+        const lineContent = sourceLine.text.trimEnd().replace(/\t/g, " ");
+        context += host.getNewLine();
+        context += lineIndent +
+            formatColorAndReset(`${sourceLine.line + 1}`.padStart(gutterWidth), gutterStyleSequence) +
+            gutterSeparator +
+            lineContent +
+            host.getNewLine();
+        context += lineIndent +
+            formatColorAndReset("".padStart(gutterWidth), gutterStyleSequence) +
+            gutterSeparator +
+            squiggleColor;
+
+        if (sourceLine.line === startPosition.line) {
+            const lastCharacter = sourceLine.line === endPosition.line
+                ? endPosition.character
+                : lineContent.length;
+            context += " ".repeat(startPosition.character);
+            context += "~".repeat(Math.max(0, lastCharacter - startPosition.character));
+        }
+        else if (sourceLine.line === endPosition.line) {
+            context += "~".repeat(endPosition.character);
+        }
+        else {
+            context += "~".repeat(lineContent.length);
+        }
+        context += resetEscapeSequence;
+        previousLine = sourceLine.line;
+    }
+
+    return context;
+}
+
+export function formatDiagnostics(diagnostics: readonly Diagnostic[], host: FormatDiagnosticsHost): string {
+    let output = "";
+    for (const diagnostic of diagnostics) {
+        const errorMessage = `${diagnosticCategoryName(diagnostic.category)} ${diagnosticPrefix(diagnostic)}${diagnostic.code}: ${flattenDiagnosticMessage(diagnostic, host.getNewLine())}${host.getNewLine()}`;
+        if (diagnostic.fileName && diagnostic.startPosition) {
+            const { line, character } = diagnostic.startPosition;
+            output += `${relativeFileName(diagnostic.fileName, host)}(${line + 1},${character + 1}): ${errorMessage}`;
+        }
+        else {
+            output += errorMessage;
+        }
+    }
+    return output;
+}
+
+export function formatDiagnosticsWithColorAndContext(
+    diagnostics: readonly Diagnostic[],
+    host: FormatDiagnosticsHost,
+): string {
+    let output = "";
+    for (const diagnostic of diagnostics) {
+        if (diagnostic.fileName && diagnostic.startPosition) {
+            output += formatLocation(diagnostic, host) + " - ";
+        }
+        output += formatColorAndReset(diagnosticCategoryName(diagnostic.category), getCategoryFormat(diagnostic.category));
+        output += formatColorAndReset(` ${diagnosticPrefix(diagnostic)}${diagnostic.code}: `, foregroundColorEscapeGrey);
+        output += flattenDiagnosticMessage(diagnostic, host.getNewLine());
+
+        if (diagnostic.fileName && diagnostic.code !== fileAppearsToBeBinaryCode) {
+            output += host.getNewLine();
+            output += formatCodeSpan(diagnostic, "", getCategoryFormat(diagnostic.category), host);
+        }
+
+        if (diagnostic.relatedInformation?.length) {
+            output += host.getNewLine();
+            for (const related of diagnostic.relatedInformation) {
+                if (related.fileName && related.startPosition) {
+                    output += host.getNewLine();
+                    output += halfIndent + formatLocation(related, host);
+                    output += formatCodeSpan(related, indent, foregroundColorEscapeCyan, host);
+                }
+                output += host.getNewLine();
+                output += indent + flattenDiagnosticMessage(related, host.getNewLine());
+            }
+        }
+        output += host.getNewLine();
+    }
+    return output;
+}
diff --git a/packages/typescript/src/api/proto.generated.ts b/packages/typescript/src/api/proto.generated.ts
index 8f49e31327626..4fde71e49fd46 100644
--- a/packages/typescript/src/api/proto.generated.ts
+++ b/packages/typescript/src/api/proto.generated.ts
@@ -125,8 +125,6 @@ export interface APIMethodInfo {
     getProgramDiagnostics: APIMethod<GetProjectDiagnosticsParams, DiagnosticResponse[] | null>;
     getGlobalDiagnostics: APIMethod<GetProjectDiagnosticsParams, DiagnosticResponse[] | null>;
     getConfigFileParsingDiagnostics: APIMethod<GetProjectDiagnosticsParams, DiagnosticResponse[] | null>;
-    formatDiagnostics: APIMethod<FormatDiagnosticsParams, FormatDiagnosticsResponse>;
-    formatDiagnosticsWithColorAndContext: APIMethod<FormatDiagnosticsParams, FormatDiagnosticsResponse>;
     printNode: APIMethod<PrintNodeParams, string>;
     formatNodeForInsertion: APIMethod<FormatNodeForInsertionParams, string>;
     emit: APIMethod<EmitParams, EmitResponse>;
@@ -761,12 +759,16 @@ export interface GetDiagnosticsParams {
 export interface DiagnosticResponse {
     /** FileName is the path of the file this diagnostic belongs to, if any. */
     fileName?: string;
-    /** SourceFileHash identifies the source text used to produce this diagnostic. */
-    sourceFileHash?: string;
     /** Pos is the start position of the diagnostic in the source file. */
     pos: number;
     /** End is the end position of the diagnostic in the source file. */
     end: number;
+    /** StartPosition is the zero-based line and UTF-16 character position of Pos. */
+    startPosition?: DiagnosticPositionResponse;
+    /** EndPosition is the zero-based line and UTF-16 character position of End. */
+    endPosition?: DiagnosticPositionResponse;
+    /** SourceLines contains the source lines needed to render this diagnostic with context. */
+    sourceLines?: DiagnosticSourceLineResponse[];
     /** Code is the diagnostic error code. */
     code: number;
     /** Category is the diagnostic category (error, warning, suggestion, message). */
@@ -783,22 +785,6 @@ export interface DiagnosticResponse {
     messageChain?: DiagnosticResponse[];
     /** RelatedInformation contains related diagnostic information, if any. */
     relatedInformation?: DiagnosticResponse[];
-    /** DisplayFileName is the host-formatted file name used only for diagnostic output. */
-    displayFileName?: string;
-}
-
-/** FormatDiagnosticsParams are parameters for diagnostic formatting methods. */
-export interface FormatDiagnosticsParams {
-    snapshot: number;
-    project: string;
-    diagnostics: readonly DiagnosticResponse[] | null;
-    newLine: string;
-}
-
-/** FormatDiagnosticsResponse is the response for diagnostic formatting methods. */
-export interface FormatDiagnosticsResponse {
-    /** Output is the fully formatted diagnostics text. */
-    output: string;
 }
 
 /** PrintNodeParams are the parameters for the printNode method. */
@@ -1056,6 +1042,16 @@ export interface CompletionEntryResponse {
     symbol?: SymbolResponse;
 }
 
+export interface DiagnosticPositionResponse {
+    line: number;
+    character: number;
+}
+
+export interface DiagnosticSourceLineResponse {
+    line: number;
+    text: string;
+}
+
 export interface EmitOutputFile {
     fileName: string;
     text: string;
diff --git a/packages/typescript/src/api/sync/api.ts b/packages/typescript/src/api/sync/api.ts
index 6934d4f86a418..47079e1de8433 100644
--- a/packages/typescript/src/api/sync/api.ts
+++ b/packages/typescript/src/api/sync/api.ts
@@ -35,6 +35,10 @@ import {
     unescapeLeadingUnderscores,
 } from "../../ast/index.ts";
 import { assertNever } from "../../internal/utils.ts";
+import {
+    formatDiagnostics,
+    formatDiagnosticsWithColorAndContext,
+} from "../diagnosticFormatter.ts";
 import {
     encodeNode,
     uint8ArrayToBase64,
@@ -53,7 +57,6 @@ import type {
     LSPConnectionOptions,
 } from "../options.ts";
 import {
-    convertToRelativePath,
     createGetCanonicalFileName,
     toPath,
 } from "../path.ts";
@@ -216,35 +219,6 @@ export interface TranspileOutput {
     sourceMapText?: string;
 }
 
-interface FormatDiagnosticRequest extends Diagnostic {
-    readonly displayFileName?: string;
-}
-
-function toFormatDiagnosticRequest(
-    diagnostic: Diagnostic,
-    host: FormatDiagnosticsHost,
-): FormatDiagnosticRequest {
-    const { messageChain, relatedInformation, ...diagnosticData } = diagnostic;
-    return {
-        ...diagnosticData,
-        ...(diagnostic.fileName
-            ? {
-                displayFileName: convertToRelativePath(
-                    diagnostic.fileName,
-                    host.getCurrentDirectory(),
-                    fileName => host.getCanonicalFileName(fileName),
-                ),
-            }
-            : {}),
-        ...(messageChain
-            ? { messageChain: messageChain.map(d => toFormatDiagnosticRequest(d, host)) }
-            : {}),
-        ...(relatedInformation
-            ? { relatedInformation: relatedInformation.map(d => toFormatDiagnosticRequest(d, host)) }
-            : {}),
-    };
-}
-
 export class API<FromLSP extends boolean = false> {
     private client: Client;
     private sourceFileCache: SourceFileCache;
@@ -1252,13 +1226,7 @@ export class Program {
         diagnostics: readonly Diagnostic[],
         host: FormatDiagnosticsHost,
     ): string {
-        const data = this.client.apiRequest("formatDiagnostics", {
-            snapshot: this.snapshotId,
-            project: this.project.id,
-            diagnostics: diagnostics.map(d => toFormatDiagnosticRequest(d, host)),
-            newLine: host.getNewLine(),
-        });
-        return data.output;
+        return formatDiagnostics(diagnostics, host);
     }
 
     /**
@@ -1268,13 +1236,7 @@ export class Program {
         diagnostics: readonly Diagnostic[],
         host: FormatDiagnosticsHost,
     ): string {
-        const data = this.client.apiRequest("formatDiagnosticsWithColorAndContext", {
-            snapshot: this.snapshotId,
-            project: this.project.id,
-            diagnostics: diagnostics.map(d => toFormatDiagnosticRequest(d, host)),
-            newLine: host.getNewLine(),
-        });
-        return data.output;
+        return formatDiagnosticsWithColorAndContext(diagnostics, host);
     }
 
     /**
@@ -1305,7 +1267,7 @@ export class Program {
             project: this.project.id,
             ...(emitOnly !== undefined ? { emitOnly } : {}),
         });
-        return toEmitOutput(response, response.diagnostics);
+        return toEmitOutput(response);
     }
 
     /**
@@ -1317,7 +1279,7 @@ export class Program {
             project: this.project.id,
             files,
         });
-        return toEmitOutput(response, response.diagnostics);
+        return toEmitOutput(response);
     }
 
     /**
@@ -1329,18 +1291,18 @@ export class Program {
             project: this.project.id,
             files,
         });
-        return toEmitOutput(response, response.diagnostics);
+        return toEmitOutput(response);
     }
 }
 
-function toEmitOutput(response: ProtocolEmitOutputResponse, diagnostics: readonly Diagnostic[]): EmitOutput {
+function toEmitOutput(response: ProtocolEmitOutputResponse): EmitOutput {
     const outputFiles = new Map<string, EmitOutputFile>();
     for (const { fileName, ...outputFile } of response.outputFiles) {
         outputFiles.set(fileName, outputFile);
     }
     return {
         emitSkipped: response.emitSkipped,
-        diagnostics,
+        diagnostics: response.diagnostics,
         outputFiles,
     };
 }
diff --git a/packages/typescript/test/async/api.test.ts b/packages/typescript/test/async/api.test.ts
index 9a7d7c9bfbfe2..51667a61df2d3 100644
--- a/packages/typescript/test/async/api.test.ts
+++ b/packages/typescript/test/async/api.test.ts
@@ -5684,8 +5684,10 @@ describe("Program - diagnostics", () => {
             const snapshot = await api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = await project.program.getSyntacticDiagnostics("/src/index.ts");
-            assert.match(diags[0].sourceFileHash!, /^[0-9a-f]{32}$/);
-            assert.deepEqual(withoutSourceFileHashes(diags), [{
+            assert.deepEqual(diags[0].startPosition, { line: 0, character: 9 });
+            assert.deepEqual(diags[0].endPosition, { line: 0, character: 10 });
+            assert.deepEqual(diags[0].sourceLines, [{ line: 0, text: source }]);
+            assert.deepEqual(withoutFormattingContext(diags), [{
                 fileName: "/src/index.ts",
                 ...rangeOf(source, "="),
                 code: 1110,
@@ -5710,7 +5712,7 @@ describe("Program - diagnostics", () => {
             const diags = await project.program.getSemanticDiagnostics("/src/index.ts");
             const declRange = rangeOf(source, "callback", 0);
             const assignRange = rangeOf(source, "callback", 1);
-            assert.deepEqual(withoutSourceFileHashes(diags), [{
+            assert.deepEqual(withoutFormattingContext(diags), [{
                 fileName: "/src/index.ts",
                 ...assignRange,
                 code: 2322,
@@ -5754,7 +5756,7 @@ describe("Program - diagnostics", () => {
             const snapshot = await api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = await project.program.getSuggestionDiagnostics("/src/index.ts");
-            assert.deepEqual(withoutSourceFileHashes(diags), [{
+            assert.deepEqual(withoutFormattingContext(diags), [{
                 fileName: "/src/index.ts",
                 ...rangeOf(source, "_unused"),
                 code: 6133,
@@ -5778,7 +5780,7 @@ describe("Program - diagnostics", () => {
             const snapshot = await api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = await project.program.getConfigFileParsingDiagnostics();
-            assert.deepEqual(withoutSourceFileHashes(diags), [{
+            assert.deepEqual(withoutFormattingContext(diags), [{
                 fileName: "/tsconfig.json",
                 ...rangeOf(config, `"invalid"`),
                 code: 6046,
@@ -5822,6 +5824,21 @@ describe("Program - diagnostics", () => {
             assert.ok(color.endsWith("\r\n"), color);
             const doubled = await project.program.formatDiagnosticsWithColorAndContext([diags[0], diags[0]], host);
             assert.equal(doubled, color + color);
+
+            const multiline = {
+                ...diags[0],
+                startPosition: { line: 0, character: 0 },
+                endPosition: { line: 6, character: 5 },
+                sourceLines: [
+                    { line: 0, text: "one\n" },
+                    { line: 1, text: "two\n" },
+                    { line: 5, text: "six\n" },
+                    { line: 6, text: "seven" },
+                ],
+            };
+            const multilineColor = await project.program.formatDiagnosticsWithColorAndContext([multiline], host);
+            assert.ok(multilineColor.includes("..."), multilineColor);
+            assert.ok(multilineColor.includes("seven"), multilineColor);
         }
         finally {
             await api.close();
@@ -5855,36 +5872,6 @@ describe("Program - diagnostics", () => {
         }
     });
 
-    test("formatDiagnostics rejects diagnostics for stale source text", async () => {
-        const api = spawnAPI({
-            "/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
-            "/index.ts": `const x: number = "oops";`,
-        });
-        try {
-            const snapshot = await api.updateSnapshot({ openProject: "/tsconfig.json" });
-            const program = snapshot.getProject("/tsconfig.json")!.program;
-            const diagnostics = await program.getSemanticDiagnostics("/index.ts");
-            const host = {
-                getCurrentDirectory: () => "/",
-                getCanonicalFileName: (fileName: string) => fileName,
-                getNewLine: () => "\n",
-            };
-            const staleDiagnostics = diagnostics.map(diagnostic => ({
-                ...diagnostic,
-                sourceFileHash: "00000000000000000000000000000000",
-            }));
-
-            // @sync: assert.throws(() =>
-            await assert.rejects( // @sync-skip
-                program.formatDiagnostics(staleDiagnostics, host),
-                /source file content has changed/,
-            );
-        }
-        finally {
-            await api.close();
-        }
-    });
-
     test("formatDiagnostics accepts cloned diagnostics and parseConfigFile diagnostics", async () => {
         const configText = `{ "compilerOptions": { "target": "invalid" } }`;
         const api = spawnAPI({
@@ -5975,7 +5962,7 @@ describe("Program - diagnostics", () => {
             const snapshot = await api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = await project.program.getBindDiagnostics("/src/index.ts");
-            assert.deepEqual(withoutSourceFileHashes(diags), [
+            assert.deepEqual(withoutFormattingContext(diags), [
                 {
                     fileName: "/src/index.ts",
                     ...rangeOf(source, "x", 0),
@@ -6007,7 +5994,7 @@ describe("Program - diagnostics", () => {
             const snapshot = await api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = await project.program.getProgramDiagnostics();
-            assert.deepEqual(withoutSourceFileHashes(diags), [
+            assert.deepEqual(withoutFormattingContext(diags), [
                 {
                     fileName: "/tsconfig.json",
                     ...rangeOf(config, `"bundler"`),
@@ -6085,7 +6072,7 @@ describe("Program - diagnostics", () => {
             const snapshot = await api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = await project.program.getSyntacticDiagnostics(["/src/a.ts", "/src/b.ts"]);
-            assert.deepEqual(withoutSourceFileHashes(diags), [
+            assert.deepEqual(withoutFormattingContext(diags), [
                 {
                     fileName: "/src/a.ts",
                     ...rangeOf(sourceA, "="),
@@ -6865,8 +6852,9 @@ function rangeOf(source: string, searchString: string, occurrence: number = 0):
     return { pos: index, end: index + searchString.length };
 }
 
-function withoutSourceFileHashes<T>(value: T): T {
-    return JSON.parse(JSON.stringify(value, (key, item) => key === "sourceFileHash" ? undefined : item)) as T;
+function withoutFormattingContext<T>(value: T): T {
+    const formattingKeys = new Set(["startPosition", "endPosition", "sourceLines"]);
+    return JSON.parse(JSON.stringify(value, (key, item) => formattingKeys.has(key) ? undefined : item)) as T;
 }
 
 function applyTextEdits(source: string, edits: readonly TextEdit[]): string {
diff --git a/packages/typescript/test/sync/api.test.ts b/packages/typescript/test/sync/api.test.ts
index b624ee2bc5f3b..e0e70e594465f 100644
--- a/packages/typescript/test/sync/api.test.ts
+++ b/packages/typescript/test/sync/api.test.ts
@@ -5692,8 +5692,10 @@ describe("Program - diagnostics", () => {
             const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = project.program.getSyntacticDiagnostics("/src/index.ts");
-            assert.match(diags[0].sourceFileHash!, /^[0-9a-f]{32}$/);
-            assert.deepEqual(withoutSourceFileHashes(diags), [{
+            assert.deepEqual(diags[0].startPosition, { line: 0, character: 9 });
+            assert.deepEqual(diags[0].endPosition, { line: 0, character: 10 });
+            assert.deepEqual(diags[0].sourceLines, [{ line: 0, text: source }]);
+            assert.deepEqual(withoutFormattingContext(diags), [{
                 fileName: "/src/index.ts",
                 ...rangeOf(source, "="),
                 code: 1110,
@@ -5718,7 +5720,7 @@ describe("Program - diagnostics", () => {
             const diags = project.program.getSemanticDiagnostics("/src/index.ts");
             const declRange = rangeOf(source, "callback", 0);
             const assignRange = rangeOf(source, "callback", 1);
-            assert.deepEqual(withoutSourceFileHashes(diags), [{
+            assert.deepEqual(withoutFormattingContext(diags), [{
                 fileName: "/src/index.ts",
                 ...assignRange,
                 code: 2322,
@@ -5762,7 +5764,7 @@ describe("Program - diagnostics", () => {
             const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = project.program.getSuggestionDiagnostics("/src/index.ts");
-            assert.deepEqual(withoutSourceFileHashes(diags), [{
+            assert.deepEqual(withoutFormattingContext(diags), [{
                 fileName: "/src/index.ts",
                 ...rangeOf(source, "_unused"),
                 code: 6133,
@@ -5786,7 +5788,7 @@ describe("Program - diagnostics", () => {
             const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = project.program.getConfigFileParsingDiagnostics();
-            assert.deepEqual(withoutSourceFileHashes(diags), [{
+            assert.deepEqual(withoutFormattingContext(diags), [{
                 fileName: "/tsconfig.json",
                 ...rangeOf(config, `"invalid"`),
                 code: 6046,
@@ -5830,6 +5832,21 @@ describe("Program - diagnostics", () => {
             assert.ok(color.endsWith("\r\n"), color);
             const doubled = project.program.formatDiagnosticsWithColorAndContext([diags[0], diags[0]], host);
             assert.equal(doubled, color + color);
+
+            const multiline = {
+                ...diags[0],
+                startPosition: { line: 0, character: 0 },
+                endPosition: { line: 6, character: 5 },
+                sourceLines: [
+                    { line: 0, text: "one\n" },
+                    { line: 1, text: "two\n" },
+                    { line: 5, text: "six\n" },
+                    { line: 6, text: "seven" },
+                ],
+            };
+            const multilineColor = project.program.formatDiagnosticsWithColorAndContext([multiline], host);
+            assert.ok(multilineColor.includes("..."), multilineColor);
+            assert.ok(multilineColor.includes("seven"), multilineColor);
         }
         finally {
             api.close();
@@ -5863,32 +5880,6 @@ describe("Program - diagnostics", () => {
         }
     });
 
-    test("formatDiagnostics rejects diagnostics for stale source text", () => {
-        const api = spawnAPI({
-            "/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
-            "/index.ts": `const x: number = "oops";`,
-        });
-        try {
-            const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
-            const program = snapshot.getProject("/tsconfig.json")!.program;
-            const diagnostics = program.getSemanticDiagnostics("/index.ts");
-            const host = {
-                getCurrentDirectory: () => "/",
-                getCanonicalFileName: (fileName: string) => fileName,
-                getNewLine: () => "\n",
-            };
-            const staleDiagnostics = diagnostics.map(diagnostic => ({
-                ...diagnostic,
-                sourceFileHash: "00000000000000000000000000000000",
-            }));
-
-            assert.throws(() => program.formatDiagnostics(staleDiagnostics, host), /source file content has changed/);
-        }
-        finally {
-            api.close();
-        }
-    });
-
     test("formatDiagnostics accepts cloned diagnostics and parseConfigFile diagnostics", () => {
         const configText = `{ "compilerOptions": { "target": "invalid" } }`;
         const api = spawnAPI({
@@ -5899,7 +5890,7 @@ describe("Program - diagnostics", () => {
             const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
             const program = snapshot.getProject("/tsconfig.json")!.program;
             const diagnostics = program.getSemanticDiagnostics("/src/index.ts");
-            const configDiagnostics = api.parseConfigFile("/tsconfig.json").errors;
+            const configDiagnostics = (api.parseConfigFile("/tsconfig.json")).errors;
             const host = {
                 getCurrentDirectory: () => "/",
                 getCanonicalFileName: (fileName: string) => fileName,
@@ -5912,9 +5903,9 @@ describe("Program - diagnostics", () => {
             ];
 
             for (const cloned of clonedDiagnostics) {
-                assert.ok(program.formatDiagnostics(cloned, host).includes("TS2322"));
+                assert.ok((program.formatDiagnostics(cloned, host)).includes("TS2322"));
             }
-            assert.ok(program.formatDiagnosticsWithColorAndContext(configDiagnostics, host).includes(configText));
+            assert.ok((program.formatDiagnosticsWithColorAndContext(configDiagnostics, host)).includes(configText));
         }
         finally {
             api.close();
@@ -5979,7 +5970,7 @@ describe("Program - diagnostics", () => {
             const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = project.program.getBindDiagnostics("/src/index.ts");
-            assert.deepEqual(withoutSourceFileHashes(diags), [
+            assert.deepEqual(withoutFormattingContext(diags), [
                 {
                     fileName: "/src/index.ts",
                     ...rangeOf(source, "x", 0),
@@ -6011,7 +6002,7 @@ describe("Program - diagnostics", () => {
             const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = project.program.getProgramDiagnostics();
-            assert.deepEqual(withoutSourceFileHashes(diags), [
+            assert.deepEqual(withoutFormattingContext(diags), [
                 {
                     fileName: "/tsconfig.json",
                     ...rangeOf(config, `"bundler"`),
@@ -6089,7 +6080,7 @@ describe("Program - diagnostics", () => {
             const snapshot = api.updateSnapshot({ openProject: "/tsconfig.json" });
             const project = snapshot.getProject("/tsconfig.json")!;
             const diags = project.program.getSyntacticDiagnostics(["/src/a.ts", "/src/b.ts"]);
-            assert.deepEqual(withoutSourceFileHashes(diags), [
+            assert.deepEqual(withoutFormattingContext(diags), [
                 {
                     fileName: "/src/a.ts",
                     ...rangeOf(sourceA, "="),
@@ -6846,8 +6837,9 @@ function rangeOf(source: string, searchString: string, occurrence: number = 0):
     return { pos: index, end: index + searchString.length };
 }
 
-function withoutSourceFileHashes<T>(value: T): T {
-    return JSON.parse(JSON.stringify(value, (key, item) => key === "sourceFileHash" ? undefined : item)) as T;
+function withoutFormattingContext<T>(value: T): T {
+    const formattingKeys = new Set(["startPosition", "endPosition", "sourceLines"]);
+    return JSON.parse(JSON.stringify(value, (key, item) => formattingKeys.has(key) ? undefined : item)) as T;
 }
 
 function applyTextEdits(source: string, edits: readonly TextEdit[]): string {
diff --git a/tsc/internal/api/format_diagnostics.go b/tsc/internal/api/format_diagnostics.go
deleted file mode 100644
index 88befd0fef292..0000000000000
--- a/tsc/internal/api/format_diagnostics.go
+++ /dev/null
@@ -1,206 +0,0 @@
-package api
-
-import (
-	"context"
-	"fmt"
-	"strings"
-
-	"github.com/microsoft/TypeScript/tsc/internal/ast"
-	"github.com/microsoft/TypeScript/tsc/internal/compiler"
-	"github.com/microsoft/TypeScript/tsc/internal/diagnostics"
-	"github.com/microsoft/TypeScript/tsc/internal/diagnosticwriter"
-	"github.com/microsoft/TypeScript/tsc/internal/locale"
-	"github.com/microsoft/TypeScript/tsc/internal/tsoptions"
-	"github.com/microsoft/TypeScript/tsc/internal/tspath"
-)
-
-// handleFormatDiagnostics formats diagnostics using source text from their snapshot.
-func (s *Session) handleFormatDiagnostics(ctx context.Context, params *FormatDiagnosticsParams, colorAndContext bool) (*FormatDiagnosticsResponse, error) {
-	sd, err := s.getSnapshotData(params.Snapshot)
-	if err != nil {
-		return nil, err
-	}
-
-	program, err := sd.getProgram(params.Project)
-	if err != nil {
-		return nil, err
-	}
-
-	resolver := newFormatFileResolver(sd, program)
-	diags := make([]diagnosticwriter.Diagnostic, len(params.Diagnostics))
-	for i, d := range params.Diagnostics {
-		diag, err := newWireDiagnostic(d, resolver)
-		if err != nil {
-			return nil, err
-		}
-		diags[i] = diag
-	}
-
-	formatOpts := &diagnosticwriter.FormattingOptions{
-		NewLine: params.NewLine,
-		ComparePathsOptions: tspath.ComparePathsOptions{
-			CurrentDirectory:          s.projectSession.GetCurrentDirectory(),
-			UseCaseSensitiveFileNames: s.projectSession.FS().UseCaseSensitiveFileNames(),
-		},
-	}
-
-	var sb strings.Builder
-	if colorAndContext {
-		diagnosticwriter.FormatDiagnosticsWithColorAndContextForAPI(&sb, diags, formatOpts)
-	} else {
-		diagnosticwriter.WriteFormatDiagnostics(&sb, diags, formatOpts)
-	}
-
-	return &FormatDiagnosticsResponse{Output: sb.String()}, nil
-}
-
-// formatFileResolver resolves source and config files from a snapshot.
-type formatFileResolver struct {
-	sd      *snapshotData
-	program *compiler.Program
-	cache   map[string]*ast.SourceFile
-}
-
-func newFormatFileResolver(sd *snapshotData, program *compiler.Program) *formatFileResolver {
-	return &formatFileResolver{
-		sd:      sd,
-		program: program,
-		cache:   make(map[string]*ast.SourceFile),
-	}
-}
-
-func (r *formatFileResolver) resolve(fileName string) *ast.SourceFile {
-	if fileName == "" {
-		return nil
-	}
-	if file, ok := r.cache[fileName]; ok {
-		return file
-	}
-	file := r.resolveUncached(fileName)
-	r.cache[fileName] = file
-	return file
-}
-
-func (r *formatFileResolver) resolveUncached(fileName string) *ast.SourceFile {
-	if file := r.program.GetSourceFile(fileName); file != nil {
-		return file
-	}
-
-	// Config files are not program source files.
-	commandLine := r.program.CommandLine()
-	if commandLine == nil || commandLine.ConfigFile == nil || commandLine.ConfigFile.SourceFile == nil {
-		return nil
-	}
-
-	requestedPath := tspath.ToPath(fileName, r.program.GetCurrentDirectory(), r.program.UseCaseSensitiveFileNames())
-	if rootConfig := commandLine.ConfigFile.SourceFile; rootConfig.Path() == requestedPath {
-		return rootConfig
-	}
-
-	for _, configFileName := range commandLine.ExtendedSourceFiles() {
-		if tspath.ToPath(configFileName, r.program.GetCurrentDirectory(), r.program.UseCaseSensitiveFileNames()) != requestedPath {
-			continue
-		}
-		configFileContent, ok := r.sd.snapshot.ReadFile(configFileName)
-		if !ok {
-			return nil
-		}
-		return tsoptions.NewTsconfigSourceFileFromFilePath(configFileName, requestedPath, configFileContent).SourceFile
-	}
-
-	return nil
-}
-
-// wireDiagnostic adapts a DiagnosticResponse to diagnosticwriter.Diagnostic.
-type wireDiagnostic struct {
-	resp    *DiagnosticResponse
-	file    diagnosticwriter.FileLike
-	pos     int // UTF-8 byte offset
-	end     int // UTF-8 byte offset
-	chain   []diagnosticwriter.Diagnostic
-	related []diagnosticwriter.Diagnostic
-}
-
-func newWireDiagnostic(
-	resp *DiagnosticResponse,
-	resolver *formatFileResolver,
-) (*wireDiagnostic, error) {
-	sourceFile := resolver.resolve(resp.FileName)
-	if resp.FileName != "" && sourceFile == nil {
-		return nil, fmt.Errorf("%w: diagnostic source file not found: %s", ErrClientError, resp.FileName)
-	}
-	if sourceFile != nil && resp.SourceFileHash != "" && sourceFileHash(sourceFile) != resp.SourceFileHash {
-		return nil, fmt.Errorf("%w: diagnostic source file content has changed: %s", ErrClientError, resp.FileName)
-	}
-
-	pos, end := resp.Pos, resp.End
-	var file diagnosticwriter.FileLike
-	if sourceFile != nil {
-		positionMap := sourceFile.GetPositionMap()
-		pos = positionMap.UTF16ToUTF8(resp.Pos)
-		end = positionMap.UTF16ToUTF8(resp.End)
-		textLength := len(sourceFile.Text())
-		pos = max(0, min(pos, textLength))
-		end = max(pos, min(end, textLength))
-		file = sourceFile
-		if resp.DisplayFileName != "" {
-			file = &diagnosticDisplayFile{
-				SourceFile: sourceFile,
-				fileName:   resp.DisplayFileName,
-			}
-		}
-	}
-
-	wd := &wireDiagnostic{resp: resp, file: file, pos: pos, end: end}
-
-	if len(resp.MessageChain) > 0 {
-		wd.chain = make([]diagnosticwriter.Diagnostic, len(resp.MessageChain))
-		for i, c := range resp.MessageChain {
-			diag, err := newWireDiagnostic(c, resolver)
-			if err != nil {
-				return nil, err
-			}
-			wd.chain[i] = diag
-		}
-	}
-	if len(resp.RelatedInformation) > 0 {
-		wd.related = make([]diagnosticwriter.Diagnostic, len(resp.RelatedInformation))
-		for i, ri := range resp.RelatedInformation {
-			diag, err := newWireDiagnostic(ri, resolver)
-			if err != nil {
-				return nil, err
-			}
-			wd.related[i] = diag
-		}
-	}
-
-	return wd, nil
-}
-
-type diagnosticDisplayFile struct {
-	*ast.SourceFile
-	fileName string
-}
-
-func (f *diagnosticDisplayFile) FileName() string {
-	return f.fileName
-}
-
-func (f *diagnosticDisplayFile) FileNameIsFormatted() bool {
-	return true
-}
-
-func (d *wireDiagnostic) File() diagnosticwriter.FileLike {
-	return d.file
-}
-
-func (d *wireDiagnostic) Pos() int                        { return d.pos }
-func (d *wireDiagnostic) End() int                        { return d.end }
-func (d *wireDiagnostic) Len() int                        { return d.end - d.pos }
-func (d *wireDiagnostic) Code() int32                     { return d.resp.Code }
-func (d *wireDiagnostic) Category() diagnostics.Category  { return d.resp.Category }
-func (d *wireDiagnostic) Source() string                  { return d.resp.Source }
-func (d *wireDiagnostic) Localize(_ locale.Locale) string { return d.resp.Text }
-
-func (d *wireDiagnostic) MessageChain() []diagnosticwriter.Diagnostic       { return d.chain }
-func (d *wireDiagnostic) RelatedInformation() []diagnosticwriter.Diagnostic { return d.related }
diff --git a/tsc/internal/api/proto.go b/tsc/internal/api/proto.go
index ce090dca07ebe..fa4418b945680 100644
--- a/tsc/internal/api/proto.go
+++ b/tsc/internal/api/proto.go
@@ -11,6 +11,7 @@ import (
 	"github.com/microsoft/TypeScript/tsc/internal/collections"
 	"github.com/microsoft/TypeScript/tsc/internal/core"
 	"github.com/microsoft/TypeScript/tsc/internal/diagnostics"
+	"github.com/microsoft/TypeScript/tsc/internal/diagnosticwriter"
 	"github.com/microsoft/TypeScript/tsc/internal/jsnum"
 	"github.com/microsoft/TypeScript/tsc/internal/json"
 	"github.com/microsoft/TypeScript/tsc/internal/locale"
@@ -18,9 +19,9 @@ import (
 	"github.com/microsoft/TypeScript/tsc/internal/lsp/lsproto"
 	"github.com/microsoft/TypeScript/tsc/internal/packagejson"
 	"github.com/microsoft/TypeScript/tsc/internal/project"
+	"github.com/microsoft/TypeScript/tsc/internal/scanner"
 	"github.com/microsoft/TypeScript/tsc/internal/tsoptions"
 	"github.com/microsoft/TypeScript/tsc/internal/tspath"
-	"github.com/zeebo/xxh3"
 )
 
 var (
@@ -182,17 +183,14 @@ const (
 	MethodGetCompletionsAtPosition Method = "getCompletionsAtPosition"
 
 	// Diagnostic methods
-	MethodGetSyntacticDiagnostics              Method = "getSyntacticDiagnostics"
-	MethodGetBindDiagnostics                   Method = "getBindDiagnostics"
-	MethodGetSemanticDiagnostics               Method = "getSemanticDiagnostics"
-	MethodGetSuggestionDiagnostics             Method = "getSuggestionDiagnostics"
-	MethodGetDeclarationDiagnostics            Method = "getDeclarationDiagnostics"
-	MethodGetProgramDiagnostics                Method = "getProgramDiagnostics"
-	MethodGetGlobalDiagnostics                 Method = "getGlobalDiagnostics"
-	MethodGetConfigFileParsingDiagnostics      Method = "getConfigFileParsingDiagnostics"
-	MethodFormatDiagnostics                    Method = "formatDiagnostics"
-	MethodFormatDiagnosticsWithColorAndContext Method = "formatDiagnosticsWithColorAndContext"
-
+	MethodGetSyntacticDiagnostics         Method = "getSyntacticDiagnostics"
+	MethodGetBindDiagnostics              Method = "getBindDiagnostics"
+	MethodGetSemanticDiagnostics          Method = "getSemanticDiagnostics"
+	MethodGetSuggestionDiagnostics        Method = "getSuggestionDiagnostics"
+	MethodGetDeclarationDiagnostics       Method = "getDeclarationDiagnostics"
+	MethodGetProgramDiagnostics           Method = "getProgramDiagnostics"
+	MethodGetGlobalDiagnostics            Method = "getGlobalDiagnostics"
+	MethodGetConfigFileParsingDiagnostics Method = "getConfigFileParsingDiagnostics"
 	// Emitter methods
 	MethodPrintNode              Method = "printNode"
 	MethodFormatNodeForInsertion Method = "formatNodeForInsertion"
@@ -469,85 +467,83 @@ var unmarshalers = map[Method]func([]byte) (any, error){
 	MethodGetThisParameterOfSignature:  unmarshallerFor[GetSignaturePropertyParams],
 	MethodGetTargetOfSignature:         unmarshallerFor[GetSignaturePropertyParams],
 
-	MethodGetContextualType:                    unmarshallerFor[GetContextualTypeParams],
-	MethodGetBaseTypeOfLiteralType:             unmarshallerFor[GetBaseTypeOfLiteralTypeParams],
-	MethodGetNonNullableType:                   unmarshallerFor[GetTypePropertyParams],
-	MethodGetTypeFromTypeNode:                  unmarshallerFor[GetTypeFromTypeNodeParams],
-	MethodGetWidenedType:                       unmarshallerFor[GetWidenedTypeParams],
-	MethodGetParameterType:                     unmarshallerFor[GetParameterTypeParams],
-	MethodGetTypeParameterAtPosition:           unmarshallerFor[GetParameterTypeParams],
-	MethodIsArrayLikeType:                      unmarshallerFor[IsArrayLikeTypeParams],
-	MethodIsTypeAssignableTo:                   unmarshallerFor[IsTypeAssignableToParams],
-	MethodGetShorthandAssignmentValueSymbol:    unmarshallerFor[GetTypeAtLocationParams],
-	MethodGetTypeOfSymbolAtLocation:            unmarshallerFor[GetTypeOfSymbolAtLocationParams],
-	MethodTypeToTypeNode:                       unmarshallerFor[TypeToTypeNodeParams],
-	MethodSignatureToSignatureDeclaration:      unmarshallerFor[SignatureToSignatureDeclarationParams],
-	MethodTypeToString:                         unmarshallerFor[TypeToTypeNodeParams],
-	MethodIsContextSensitive:                   unmarshallerFor[GetContextualTypeParams],
-	MethodGetReturnTypeOfSignature:             unmarshallerFor[GetSignaturePropertyParams],
-	MethodGetRestTypeOfSignature:               unmarshallerFor[CheckerSignatureParams],
-	MethodGetTypePredicateOfSignature:          unmarshallerFor[CheckerSignatureParams],
-	MethodGetBaseTypes:                         unmarshallerFor[CheckerTypeParams],
-	MethodGetPropertiesOfType:                  unmarshallerFor[CheckerTypeParams],
-	MethodGetApparentPropertiesOfType:          unmarshallerFor[GetTypePropertyParams],
-	MethodGetApparentType:                      unmarshallerFor[GetTypePropertyParams],
-	MethodGetReducedType:                       unmarshallerFor[GetTypePropertyParams],
-	MethodGetPropertyOfType:                    unmarshallerFor[GetPropertyOfTypeParams],
-	MethodGetIndexInfosOfType:                  unmarshallerFor[CheckerTypeParams],
-	MethodGetConstraintOfTypeParameter:         unmarshallerFor[GetTypePropertyParams],
-	MethodGetBaseConstraintOfType:              unmarshallerFor[CheckerTypeParams],
-	MethodGetDefaultFromTypeParameter:          unmarshallerFor[GetTypePropertyParams],
-	MethodGetTypeArguments:                     unmarshallerFor[CheckerTypeParams],
-	MethodGetImportAdderEdits:                  unmarshallerFor[GetImportAdderEditsParams],
-	MethodGetConstantValue:                     unmarshallerFor[CheckerNodeParams],
-	MethodGetSignatureFromDeclaration:          unmarshallerFor[CheckerNodeParams],
-	MethodGetExportSpecifierLocalTarget:        unmarshallerFor[CheckerNodeParams],
-	MethodGetAliasedSymbol:                     unmarshallerFor[CheckerSymbolParams],
-	MethodGetImmediateAliasedSymbol:            unmarshallerFor[CheckerSymbolParams],
-	MethodGetFullyQualifiedName:                unmarshallerFor[CheckerSymbolParams],
-	MethodGetExportsOfModule:                   unmarshallerFor[CheckerSymbolParams],
-	MethodGetMemberInModuleExports:             unmarshallerFor[GetMemberInModuleExportsParams],
-	MethodGetJSDocTags:                         unmarshallerFor[CheckerSymbolParams],
-	MethodGetDocumentationComment:              unmarshallerFor[CheckerSymbolParams],
-	MethodIsArrayType:                          unmarshallerFor[CheckerTypeParams],
-	MethodIsTupleType:                          unmarshallerFor[CheckerTypeParams],
-	MethodGetReferencesToSymbolInFile:          unmarshallerFor[GetReferencesToSymbolInFileParams],
-	MethodGetReferencedSymbolsForNode:          unmarshallerFor[GetReferencedSymbolsForNodeParams],
-	MethodGetSignatureUsages:                   unmarshallerFor[GetSignatureUsagesParams],
-	MethodGetCompletionsAtPosition:             unmarshallerFor[GetCompletionsAtPositionParams],
-	MethodPrintNode:                            unmarshallerFor[PrintNodeParams],
-	MethodFormatNodeForInsertion:               unmarshallerFor[FormatNodeForInsertionParams],
-	MethodEmit:                                 unmarshallerFor[EmitParams],
-	MethodEmitToString:                         unmarshallerFor[EmitParams],
-	MethodGetJavaScriptEmit:                    unmarshallerFor[SelectedFilesEmitParams],
-	MethodGetDeclarationEmit:                   unmarshallerFor[SelectedFilesEmitParams],
-	MethodGetAnyType:                           unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetStringType:                        unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetNumberType:                        unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetBooleanType:                       unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetVoidType:                          unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetUndefinedType:                     unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetNullType:                          unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetNeverType:                         unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetUnknownType:                       unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetBigIntType:                        unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetESSymbolType:                      unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetNonPrimitiveType:                  unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetWellKnownSymbols:                  unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetWellKnownSignatures:               unmarshallerFor[GetIntrinsicTypeParams],
-	MethodGetSyntacticDiagnostics:              unmarshallerFor[GetDiagnosticsParams],
-	MethodGetBindDiagnostics:                   unmarshallerFor[GetDiagnosticsParams],
-	MethodGetSemanticDiagnostics:               unmarshallerFor[GetDiagnosticsParams],
-	MethodGetSuggestionDiagnostics:             unmarshallerFor[GetDiagnosticsParams],
-	MethodGetDeclarationDiagnostics:            unmarshallerFor[GetDiagnosticsParams],
-	MethodGetProgramDiagnostics:                unmarshallerFor[GetProjectDiagnosticsParams],
-	MethodGetGlobalDiagnostics:                 unmarshallerFor[GetProjectDiagnosticsParams],
-	MethodGetConfigFileParsingDiagnostics:      unmarshallerFor[GetProjectDiagnosticsParams],
-	MethodFormatDiagnostics:                    unmarshallerFor[FormatDiagnosticsParams],
-	MethodFormatDiagnosticsWithColorAndContext: unmarshallerFor[FormatDiagnosticsParams],
-	MethodStartCPUProfile:                      unmarshallerFor[ProfileParams],
-	MethodStopCPUProfile:                       noParams,
-	MethodSaveHeapProfile:                      unmarshallerFor[ProfileParams],
+	MethodGetContextualType:                 unmarshallerFor[GetContextualTypeParams],
+	MethodGetBaseTypeOfLiteralType:          unmarshallerFor[GetBaseTypeOfLiteralTypeParams],
+	MethodGetNonNullableType:                unmarshallerFor[GetTypePropertyParams],
+	MethodGetTypeFromTypeNode:               unmarshallerFor[GetTypeFromTypeNodeParams],
+	MethodGetWidenedType:                    unmarshallerFor[GetWidenedTypeParams],
+	MethodGetParameterType:                  unmarshallerFor[GetParameterTypeParams],
+	MethodGetTypeParameterAtPosition:        unmarshallerFor[GetParameterTypeParams],
+	MethodIsArrayLikeType:                   unmarshallerFor[IsArrayLikeTypeParams],
+	MethodIsTypeAssignableTo:                unmarshallerFor[IsTypeAssignableToParams],
+	MethodGetShorthandAssignmentValueSymbol: unmarshallerFor[GetTypeAtLocationParams],
+	MethodGetTypeOfSymbolAtLocation:         unmarshallerFor[GetTypeOfSymbolAtLocationParams],
+	MethodTypeToTypeNode:                    unmarshallerFor[TypeToTypeNodeParams],
+	MethodSignatureToSignatureDeclaration:   unmarshallerFor[SignatureToSignatureDeclarationParams],
+	MethodTypeToString:                      unmarshallerFor[TypeToTypeNodeParams],
+	MethodIsContextSensitive:                unmarshallerFor[GetContextualTypeParams],
+	MethodGetReturnTypeOfSignature:          unmarshallerFor[GetSignaturePropertyParams],
+	MethodGetRestTypeOfSignature:            unmarshallerFor[CheckerSignatureParams],
+	MethodGetTypePredicateOfSignature:       unmarshallerFor[CheckerSignatureParams],
+	MethodGetBaseTypes:                      unmarshallerFor[CheckerTypeParams],
+	MethodGetPropertiesOfType:               unmarshallerFor[CheckerTypeParams],
+	MethodGetApparentPropertiesOfType:       unmarshallerFor[GetTypePropertyParams],
+	MethodGetApparentType:                   unmarshallerFor[GetTypePropertyParams],
+	MethodGetReducedType:                    unmarshallerFor[GetTypePropertyParams],
+	MethodGetPropertyOfType:                 unmarshallerFor[GetPropertyOfTypeParams],
+	MethodGetIndexInfosOfType:               unmarshallerFor[CheckerTypeParams],
+	MethodGetConstraintOfTypeParameter:      unmarshallerFor[GetTypePropertyParams],
+	MethodGetBaseConstraintOfType:           unmarshallerFor[CheckerTypeParams],
+	MethodGetDefaultFromTypeParameter:       unmarshallerFor[GetTypePropertyParams],
+	MethodGetTypeArguments:                  unmarshallerFor[CheckerTypeParams],
+	MethodGetImportAdderEdits:               unmarshallerFor[GetImportAdderEditsParams],
+	MethodGetConstantValue:                  unmarshallerFor[CheckerNodeParams],
+	MethodGetSignatureFromDeclaration:       unmarshallerFor[CheckerNodeParams],
+	MethodGetExportSpecifierLocalTarget:     unmarshallerFor[CheckerNodeParams],
+	MethodGetAliasedSymbol:                  unmarshallerFor[CheckerSymbolParams],
+	MethodGetImmediateAliasedSymbol:         unmarshallerFor[CheckerSymbolParams],
+	MethodGetFullyQualifiedName:             unmarshallerFor[CheckerSymbolParams],
+	MethodGetExportsOfModule:                unmarshallerFor[CheckerSymbolParams],
+	MethodGetMemberInModuleExports:          unmarshallerFor[GetMemberInModuleExportsParams],
+	MethodGetJSDocTags:                      unmarshallerFor[CheckerSymbolParams],
+	MethodGetDocumentationComment:           unmarshallerFor[CheckerSymbolParams],
+	MethodIsArrayType:                       unmarshallerFor[CheckerTypeParams],
+	MethodIsTupleType:                       unmarshallerFor[CheckerTypeParams],
+	MethodGetReferencesToSymbolInFile:       unmarshallerFor[GetReferencesToSymbolInFileParams],
+	MethodGetReferencedSymbolsForNode:       unmarshallerFor[GetReferencedSymbolsForNodeParams],
+	MethodGetSignatureUsages:                unmarshallerFor[GetSignatureUsagesParams],
+	MethodGetCompletionsAtPosition:          unmarshallerFor[GetCompletionsAtPositionParams],
+	MethodPrintNode:                         unmarshallerFor[PrintNodeParams],
+	MethodFormatNodeForInsertion:            unmarshallerFor[FormatNodeForInsertionParams],
+	MethodEmit:                              unmarshallerFor[EmitParams],
+	MethodEmitToString:                      unmarshallerFor[EmitParams],
+	MethodGetJavaScriptEmit:                 unmarshallerFor[SelectedFilesEmitParams],
+	MethodGetDeclarationEmit:                unmarshallerFor[SelectedFilesEmitParams],
+	MethodGetAnyType:                        unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetStringType:                     unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetNumberType:                     unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetBooleanType:                    unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetVoidType:                       unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetUndefinedType:                  unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetNullType:                       unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetNeverType:                      unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetUnknownType:                    unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetBigIntType:                     unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetESSymbolType:                   unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetNonPrimitiveType:               unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetWellKnownSymbols:               unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetWellKnownSignatures:            unmarshallerFor[GetIntrinsicTypeParams],
+	MethodGetSyntacticDiagnostics:           unmarshallerFor[GetDiagnosticsParams],
+	MethodGetBindDiagnostics:                unmarshallerFor[GetDiagnosticsParams],
+	MethodGetSemanticDiagnostics:            unmarshallerFor[GetDiagnosticsParams],
+	MethodGetSuggestionDiagnostics:          unmarshallerFor[GetDiagnosticsParams],
+	MethodGetDeclarationDiagnostics:         unmarshallerFor[GetDiagnosticsParams],
+	MethodGetProgramDiagnostics:             unmarshallerFor[GetProjectDiagnosticsParams],
+	MethodGetGlobalDiagnostics:              unmarshallerFor[GetProjectDiagnosticsParams],
+	MethodGetConfigFileParsingDiagnostics:   unmarshallerFor[GetProjectDiagnosticsParams],
+	MethodStartCPUProfile:                   unmarshallerFor[ProfileParams],
+	MethodStopCPUProfile:                    noParams,
+	MethodSaveHeapProfile:                   unmarshallerFor[ProfileParams],
 }
 
 type ParseConfigFileParams struct {
@@ -1420,12 +1416,16 @@ type GetProjectDiagnosticsParams struct {
 type DiagnosticResponse struct {
 	// FileName is the path of the file this diagnostic belongs to, if any.
 	FileName string `json:"fileName,omitempty"`
-	// SourceFileHash identifies the source text used to produce this diagnostic.
-	SourceFileHash string `json:"sourceFileHash,omitempty"`
 	// Pos is the start position of the diagnostic in the source file.
 	Pos int `json:"pos"`
 	// End is the end position of the diagnostic in the source file.
 	End int `json:"end"`
+	// StartPosition is the zero-based line and UTF-16 character position of Pos.
+	StartPosition *DiagnosticPositionResponse `json:"startPosition,omitempty"`
+	// EndPosition is the zero-based line and UTF-16 character position of End.
+	EndPosition *DiagnosticPositionResponse `json:"endPosition,omitempty"`
+	// SourceLines contains the source lines needed to render this diagnostic with context.
+	SourceLines []*DiagnosticSourceLineResponse `json:"sourceLines,omitempty"`
 	// Code is the diagnostic error code.
 	Code int32 `json:"code"`
 	// Category is the diagnostic category (error, warning, suggestion, message).
@@ -1442,27 +1442,57 @@ type DiagnosticResponse struct {
 	MessageChain []*DiagnosticResponse `json:"messageChain,omitempty"`
 	// RelatedInformation contains related diagnostic information, if any.
 	RelatedInformation []*DiagnosticResponse `json:"relatedInformation,omitempty"`
-	// DisplayFileName is the host-formatted file name used only for diagnostic output.
-	DisplayFileName string `json:"displayFileName,omitempty"`
 }
 
-func sourceFileHash(file *ast.SourceFile) string {
-	hash := file.Hash
-	if hash == (xxh3.Uint128{}) {
-		hash = xxh3.Hash128([]byte(file.Text()))
+type DiagnosticPositionResponse struct {
+	Line      int              `json:"line"`
+	Character core.UTF16Offset `json:"character"`
+}
+
+type DiagnosticSourceLineResponse struct {
+	Line int    `json:"line"`
+	Text string `json:"text"`
+}
+
+func diagnosticSourceLines(file diagnosticwriter.FileLike, firstLine int, lastLine int) []*DiagnosticSourceLineResponse {
+	lineMap := file.ECMALineMap()
+	if len(lineMap) == 0 {
+		return nil
+	}
+
+	lines := make([]int, 0, min(lastLine-firstLine+1, 4))
+	if lastLine-firstLine >= 4 {
+		lines = append(lines, firstLine, firstLine+1, lastLine-1, lastLine)
+	} else {
+		for line := firstLine; line <= lastLine; line++ {
+			lines = append(lines, line)
+		}
+	}
+
+	text := file.Text()
+	result := make([]*DiagnosticSourceLineResponse, 0, len(lines))
+	for _, line := range lines {
+		start := int(lineMap[line])
+		end := len(text)
+		if line+1 < len(lineMap) {
+			end = int(lineMap[line+1])
+		}
+		result = append(result, &DiagnosticSourceLineResponse{Line: line, Text: text[start:end]})
 	}
-	return fmt.Sprintf("%016x%016x", hash.Hi, hash.Lo)
+	return result
 }
 
 // NewDiagnosticResponse converts an ast.Diagnostic to a DiagnosticResponse.
 func NewDiagnosticResponse(d *ast.Diagnostic) *DiagnosticResponse {
-	pos := d.Pos()
-	end := d.End()
+	return newDiagnosticResponse(diagnosticwriter.WrapASTDiagnostic(d))
+}
+
+func newDiagnosticResponse(d *diagnosticwriter.ASTDiagnostic) *DiagnosticResponse {
 	file := d.File()
+	pos, end := d.Pos(), d.End()
 	if file != nil {
-		positionMap := file.GetPositionMap()
-		pos = positionMap.UTF8ToUTF16(pos)
-		end = positionMap.UTF8ToUTF16(end)
+		pos = max(0, min(pos, len(file.Text())))
+		end = max(pos, min(end, len(file.Text())))
 	}
 	resp := &DiagnosticResponse{
 		Pos:                pos,
@@ -1471,26 +1501,32 @@ func NewDiagnosticResponse(d *ast.Diagnostic) *DiagnosticResponse {
 		Category:           d.Category(),
 		Source:             d.Source(),
 		Text:               d.Localize(locale.Default),
-		ReportsUnnecessary: d.ReportsUnnecessary(),
-		ReportsDeprecated:  d.ReportsDeprecated(),
+		ReportsUnnecessary: d.Diagnostic.ReportsUnnecessary(),
+		ReportsDeprecated:  d.Diagnostic.ReportsDeprecated(),
 	}
 
 	if file != nil {
 		resp.FileName = file.FileName()
-		resp.SourceFileHash = sourceFileHash(file)
+		resp.Pos = int(core.UTF16Len(file.Text()[:pos]))
+		resp.End = int(core.UTF16Len(file.Text()[:end]))
+		startLine, startCharacter := scanner.GetECMALineAndUTF16CharacterOfPosition(file, pos)
+		endLine, endCharacter := scanner.GetECMALineAndUTF16CharacterOfPosition(file, end)
+		resp.StartPosition = &DiagnosticPositionResponse{Line: startLine, Character: startCharacter}
+		resp.EndPosition = &DiagnosticPositionResponse{Line: endLine, Character: endCharacter}
+		resp.SourceLines = diagnosticSourceLines(file, startLine, endLine)
 	}
 
 	if chain := d.MessageChain(); len(chain) > 0 {
 		resp.MessageChain = make([]*DiagnosticResponse, len(chain))
 		for i, c := range chain {
-			resp.MessageChain[i] = NewDiagnosticResponse(c)
+			resp.MessageChain[i] = newDiagnosticResponse(c.(*diagnosticwriter.ASTDiagnostic))
 		}
 	}
 
 	if related := d.RelatedInformation(); len(related) > 0 {
 		resp.RelatedInformation = make([]*DiagnosticResponse, len(related))
 		for i, r := range related {
-			resp.RelatedInformation[i] = NewDiagnosticResponse(r)
+			resp.RelatedInformation[i] = newDiagnosticResponse(r.(*diagnosticwriter.ASTDiagnostic))
 		}
 	}
 
@@ -1509,20 +1545,6 @@ func NewDiagnosticResponses(diags []*ast.Diagnostic) []*DiagnosticResponse {
 	return result
 }
 
-// FormatDiagnosticsParams are parameters for diagnostic formatting methods.
-type FormatDiagnosticsParams struct {
-	Snapshot    SnapshotID            `json:"snapshot"`
-	Project     ProjectID             `json:"project"`
-	Diagnostics []*DiagnosticResponse `json:"diagnostics"`
-	NewLine     string                `json:"newLine"`
-}
-
-// FormatDiagnosticsResponse is the response for diagnostic formatting methods.
-type FormatDiagnosticsResponse struct {
-	// Output is the fully formatted diagnostics text.
-	Output string `json:"output"`
-}
-
 func unmarshalPayload(method string, payload json.Value) (any, error) {
 	unmarshaler, ok := unmarshalers[Method(method)]
 	if !ok {
diff --git a/tsc/internal/api/proto_test.go b/tsc/internal/api/proto_test.go
index 32bbd8c9e6536..e5add0c137345 100644
--- a/tsc/internal/api/proto_test.go
+++ b/tsc/internal/api/proto_test.go
@@ -64,7 +64,7 @@ func TestDocumentIdentifierUnmarshalJSON(t *testing.T) {
 	}
 }
 
-func TestNewDiagnosticResponseUsesUTF16Offsets(t *testing.T) {
+func TestNewDiagnosticResponseIncludesFormattingContext(t *testing.T) {
 	t.Parallel()
 
 	text := "const 💩 = 1;"
@@ -76,9 +76,29 @@ func TestNewDiagnosticResponseUsesUTF16Offsets(t *testing.T) {
 	diag := ast.NewDiagnostic(file, core.NewTextRange(pos, end), diagnostics.Expression_expected)
 	resp := api.NewDiagnosticResponse(diag)
 
-	assert.Equal(t, len(resp.SourceFileHash), 32)
 	assert.Equal(t, resp.Pos, 9)
 	assert.Equal(t, resp.End, 10)
+	assert.DeepEqual(t, resp.StartPosition, &api.DiagnosticPositionResponse{Line: 0, Character: 9})
+	assert.DeepEqual(t, resp.EndPosition, &api.DiagnosticPositionResponse{Line: 0, Character: 10})
+	assert.DeepEqual(t, resp.SourceLines, []*api.DiagnosticSourceLineResponse{{Line: 0, Text: text}})
 	assert.Equal(t, resp.Pos, file.GetPositionMap().UTF8ToUTF16(pos))
 	assert.Equal(t, resp.End, file.GetPositionMap().UTF8ToUTF16(end))
 }
+
+func TestNewDiagnosticResponseTruncatesLongFormattingContext(t *testing.T) {
+	t.Parallel()
+
+	text := "one\ntwo\nthree\nfour\nfive\nsix\nseven"
+	file := parser.ParseSourceFile(ast.SourceFileParseOptions{FileName: "/multiline.ts"}, text, core.ScriptKindTS)
+	diag := ast.NewDiagnostic(file, core.NewTextRange(0, len(text)), diagnostics.Expression_expected)
+	resp := api.NewDiagnosticResponse(diag)
+
+	assert.DeepEqual(t, resp.StartPosition, &api.DiagnosticPositionResponse{Line: 0, Character: 0})
+	assert.DeepEqual(t, resp.EndPosition, &api.DiagnosticPositionResponse{Line: 6, Character: 5})
+	assert.DeepEqual(t, resp.SourceLines, []*api.DiagnosticSourceLineResponse{
+		{Line: 0, Text: "one\n"},
+		{Line: 1, Text: "two\n"},
+		{Line: 5, Text: "six\n"},
+		{Line: 6, Text: "seven"},
+	})
+}
diff --git a/tsc/internal/api/session.go b/tsc/internal/api/session.go
index 1e2893e2a3b62..d5c668385b849 100644
--- a/tsc/internal/api/session.go
+++ b/tsc/internal/api/session.go
@@ -861,10 +861,6 @@ func (s *Session) HandleRequest(ctx context.Context, method string, params json.
 		return s.handleGetGlobalDiagnostics(ctx, parsed.(*GetProjectDiagnosticsParams))
 	case string(MethodGetConfigFileParsingDiagnostics):
 		return s.handleGetConfigFileParsingDiagnostics(ctx, parsed.(*GetProjectDiagnosticsParams))
-	case string(MethodFormatDiagnostics):
-		return s.handleFormatDiagnostics(ctx, parsed.(*FormatDiagnosticsParams), false /*colorAndContext*/)
-	case string(MethodFormatDiagnosticsWithColorAndContext):
-		return s.handleFormatDiagnostics(ctx, parsed.(*FormatDiagnosticsParams), true /*colorAndContext*/)
 	case string(MethodStartCPUProfile):
 		return s.handleStartCPUProfile(ctx, parsed.(*ProfileParams))
 	case string(MethodStopCPUProfile):
diff --git a/tsc/internal/api/session_format_diagnostics_test.go b/tsc/internal/api/session_format_diagnostics_test.go
deleted file mode 100644
index c547f7b5242d8..0000000000000
--- a/tsc/internal/api/session_format_diagnostics_test.go
+++ /dev/null
@@ -1,344 +0,0 @@
-package api
-
-import (
-	"context"
-	"fmt"
-	"strings"
-	"testing"
-
-	"github.com/microsoft/TypeScript/tsc/internal/bundled"
-	"github.com/microsoft/TypeScript/tsc/internal/diagnostics"
-	"github.com/microsoft/TypeScript/tsc/internal/testutil/projecttestutil"
-	"github.com/zeebo/xxh3"
-	"gotest.tools/v3/assert"
-)
-
-func sourceFileHashForText(text string) string {
-	hash := xxh3.Hash128([]byte(text))
-	return fmt.Sprintf("%016x%016x", hash.Hi, hash.Lo)
-}
-
-func setupFormatSession(t *testing.T, files map[string]any, mainFile string) (*Session, SnapshotID, ProjectID) {
-	t.Helper()
-	projectSession, _ := projecttestutil.Setup(files)
-	t.Cleanup(projectSession.Close)
-	session := NewSession(projectSession, nil)
-	t.Cleanup(session.Close)
-
-	ctx := context.Background()
-	snap, err := session.handleUpdateSnapshot(ctx, &UpdateSnapshotParams{
-		OpenFiles: []DocumentIdentifier{{FileName: mainFile}},
-	})
-	assert.NilError(t, err)
-	proj, err := session.handleGetDefaultProjectForFile(ctx, &GetDefaultProjectForFileParams{
-		Snapshot: snap.Snapshot,
-		File:     DocumentIdentifier{FileName: mainFile},
-	})
-	assert.NilError(t, err)
-	assert.Assert(t, proj != nil, "file should resolve to a default project")
-	return session, snap.Snapshot, proj.Id
-}
-
-func formatDiagnosticsParams(snapshot SnapshotID, project ProjectID, diagnostics []*DiagnosticResponse) *FormatDiagnosticsParams {
-	return &FormatDiagnosticsParams{
-		Snapshot:    snapshot,
-		Project:     project,
-		Diagnostics: diagnostics,
-		NewLine:     "\n",
-	}
-}
-
-func TestFormatDiagnostics(t *testing.T) {
-	t.Parallel()
-	if !bundled.Embedded {
-		t.Skip("bundled files are not embedded")
-	}
-
-	const fileName = "/home/projects/p/src/index.ts"
-	const content = "const x: number = \"oops\";\n"
-	session, snapshot, project := setupFormatSession(t, map[string]any{
-		"/home/projects/p/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
-		fileName:                         content,
-	}, fileName)
-	ctx := context.Background()
-
-	diags, err := session.handleGetSemanticDiagnostics(ctx, &GetDiagnosticsParams{
-		Snapshot: snapshot,
-		Project:  project,
-		Files:    []DocumentIdentifier{{FileName: fileName}},
-	})
-	assert.NilError(t, err)
-	assert.Equal(t, len(diags), 1)
-
-	plain, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, diags), false /*colorAndContext*/)
-	assert.NilError(t, err)
-	assert.Equal(t, plain.Output,
-		"home/projects/p/src/index.ts(1,7): error TS2322: Type 'string' is not assignable to type 'number'.\n")
-
-	color, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, diags), true /*colorAndContext*/)
-	assert.NilError(t, err)
-	assert.Assert(t, strings.Contains(color.Output, "home/projects/p/src/index.ts"))
-	assert.Assert(t, strings.Contains(color.Output, "error"))
-	assert.Assert(t, strings.Contains(color.Output, "TS2322: "))
-	assert.Assert(t, strings.Contains(color.Output, "Type 'string' is not assignable to type 'number'."))
-	assert.Assert(t, strings.Contains(color.Output, "const x: number = \"oops\";"))
-	assert.Assert(t, strings.Contains(color.Output, "~"))
-	assert.Assert(t, strings.Contains(color.Output, "\x1b["))
-}
-
-func TestFormatDiagnosticsPreservesHostFormattedAbsolutePath(t *testing.T) {
-	t.Parallel()
-	if !bundled.Embedded {
-		t.Skip("bundled files are not embedded")
-	}
-
-	const fileName = "/home/projects/p/src/index.ts"
-	session, snapshot, project := setupFormatSession(t, map[string]any{
-		"/home/projects/p/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
-		fileName:                         `const x: number = "oops";`,
-	}, fileName)
-	ctx := context.Background()
-
-	diags, err := session.handleGetSemanticDiagnostics(ctx, &GetDiagnosticsParams{
-		Snapshot: snapshot,
-		Project:  project,
-		Files:    []DocumentIdentifier{{FileName: fileName}},
-	})
-	assert.NilError(t, err)
-	assert.Equal(t, len(diags), 1)
-	diags[0].DisplayFileName = "/different/root/index.ts"
-
-	params := formatDiagnosticsParams(snapshot, project, diags)
-	plain, err := session.handleFormatDiagnostics(ctx, params, false)
-	assert.NilError(t, err)
-	assert.Assert(t, strings.HasPrefix(plain.Output, "/different/root/index.ts(1,7): "))
-
-	color, err := session.handleFormatDiagnostics(ctx, params, true)
-	assert.NilError(t, err)
-	assert.Assert(t, strings.Contains(color.Output, "\x1b[96m/different/root/index.ts\x1b[0m:"))
-}
-
-func TestFormatDiagnosticsConfigFileContext(t *testing.T) {
-	t.Parallel()
-	if !bundled.Embedded {
-		t.Skip("bundled files are not embedded")
-	}
-
-	const configFileName = "/home/projects/p/tsconfig.json"
-	const config = "{ \"compilerOptions\": { \"target\": \"invalid\" } }"
-	const mainFile = "/home/projects/p/src/index.ts"
-	session, snapshot, project := setupFormatSession(t, map[string]any{
-		configFileName: config,
-		mainFile:       "export const x = 1;\n",
-	}, mainFile)
-	ctx := context.Background()
-
-	diags, err := session.handleGetConfigFileParsingDiagnostics(ctx, &GetProjectDiagnosticsParams{
-		Snapshot: snapshot, Project: project,
-	})
-	assert.NilError(t, err)
-	assert.Equal(t, len(diags), 1)
-	assert.Equal(t, diags[0].FileName, configFileName)
-
-	plain, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, diags), false)
-	assert.NilError(t, err)
-	assert.Assert(t, strings.HasPrefix(plain.Output, "home/projects/p/tsconfig.json(1,34): error TS6046: "))
-
-	color, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, diags), true)
-	assert.NilError(t, err)
-	assert.Assert(t, strings.Contains(color.Output, "\"target\": \"invalid\""))
-	assert.Assert(t, strings.Contains(color.Output, "~~~~~~~~~"))
-}
-
-func TestFormatDiagnosticsWithoutFile(t *testing.T) {
-	t.Parallel()
-	if !bundled.Embedded {
-		t.Skip("bundled files are not embedded")
-	}
-
-	const fileName = "/home/projects/p/src/index.ts"
-	session, snapshot, project := setupFormatSession(t, map[string]any{
-		"/home/projects/p/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
-		fileName:                         "export const x = 1;\n",
-	}, fileName)
-	ctx := context.Background()
-
-	fileless := []*DiagnosticResponse{{
-		Code:     1234,
-		Category: diagnostics.CategoryError,
-		Text:     "Some global problem.",
-		RelatedInformation: []*DiagnosticResponse{{
-			Code:     5678,
-			Category: diagnostics.CategoryMessage,
-			Text:     "Additional context.",
-		}},
-	}}
-
-	plain, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, fileless), false)
-	assert.NilError(t, err)
-	assert.Equal(t, plain.Output, "error TS1234: Some global problem.\n")
-
-	color, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, fileless), true)
-	assert.NilError(t, err)
-	assert.Equal(t, color.Output,
-		"\x1b[91merror\x1b[0m\x1b[90m TS1234: \x1b[0mSome global problem.\n\n    Additional context.\n")
-}
-
-func TestFormatDiagnosticsAllowsUnhashedDiagnosticsAndClampsOutOfRangePositions(t *testing.T) {
-	t.Parallel()
-	if !bundled.Embedded {
-		t.Skip("bundled files are not embedded")
-	}
-
-	const fileName = "/home/projects/p/src/index.ts"
-	session, snapshot, project := setupFormatSession(t, map[string]any{
-		"/home/projects/p/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
-		fileName:                         "export const x = 1;\n",
-	}, fileName)
-	ctx := context.Background()
-
-	stale := []*DiagnosticResponse{{
-		FileName: fileName,
-		Pos:      100_000,
-		End:      200_000,
-		Code:     1234,
-		Category: diagnostics.CategoryError,
-		Text:     "Manually constructed diagnostic.",
-	}}
-
-	plain, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, stale), false)
-	assert.NilError(t, err)
-	assert.Equal(t, plain.Output,
-		"home/projects/p/src/index.ts(2,1): error TS1234: Manually constructed diagnostic.\n")
-
-	color, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, stale), true)
-	assert.NilError(t, err)
-	assert.Assert(t, strings.Contains(color.Output, "TS1234: "))
-	assert.Assert(t, strings.Contains(color.Output, "Manually constructed diagnostic."))
-}
-
-func TestFormatDiagnosticsRejectsStaleOrMissingSources(t *testing.T) {
-	t.Parallel()
-	if !bundled.Embedded {
-		t.Skip("bundled files are not embedded")
-	}
-
-	const fileName = "/home/projects/p/src/index.ts"
-	session, snapshot, project := setupFormatSession(t, map[string]any{
-		"/home/projects/p/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
-		fileName:                         "export const x = 1;\n",
-	}, fileName)
-	ctx := context.Background()
-
-	stale := formatDiagnosticsParams(snapshot, project, []*DiagnosticResponse{{
-		FileName:       fileName,
-		SourceFileHash: sourceFileHashForText("different content"),
-		Code:           1234,
-		Category:       diagnostics.CategoryError,
-		Text:           "Stale diagnostic.",
-	}})
-	_, err := session.handleFormatDiagnostics(ctx, stale, false)
-	assert.ErrorContains(t, err, "diagnostic source file content has changed")
-
-	missing := formatDiagnosticsParams(snapshot, project, []*DiagnosticResponse{{
-		FileName: "/home/projects/p/src/missing.ts",
-		Code:     1234,
-		Category: diagnostics.CategoryError,
-		Text:     "Missing source.",
-	}})
-	_, err = session.handleFormatDiagnostics(ctx, missing, false)
-	assert.ErrorContains(t, err, "diagnostic source file not found")
-}
-
-func TestFormatDiagnosticsNonASCIIPositions(t *testing.T) {
-	t.Parallel()
-	if !bundled.Embedded {
-		t.Skip("bundled files are not embedded")
-	}
-
-	const fileName = "/home/projects/p/src/index.ts"
-	// "é" is 2 UTF-8 bytes and 1 UTF-16 code unit.
-	const content = "const café = 1;\nconst x: number = \"oops\";\n"
-	session, snapshot, project := setupFormatSession(t, map[string]any{
-		"/home/projects/p/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
-		fileName:                         content,
-	}, fileName)
-	ctx := context.Background()
-
-	diags, err := session.handleGetSemanticDiagnostics(ctx, &GetDiagnosticsParams{
-		Snapshot: snapshot, Project: project, Files: []DocumentIdentifier{{FileName: fileName}},
-	})
-	assert.NilError(t, err)
-	assert.Equal(t, len(diags), 1)
-
-	plain, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, diags), false)
-	assert.NilError(t, err)
-	assert.Equal(t, plain.Output,
-		"home/projects/p/src/index.ts(2,7): error TS2322: Type 'string' is not assignable to type 'number'.\n")
-
-	color, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, diags), true)
-	assert.NilError(t, err)
-	assert.Assert(t, strings.Contains(color.Output, "const x: number = \"oops\";"))
-	assert.Assert(t, strings.Contains(color.Output, "~"))
-}
-
-func TestFormatDiagnosticsAstralPositions(t *testing.T) {
-	t.Parallel()
-	if !bundled.Embedded {
-		t.Skip("bundled files are not embedded")
-	}
-
-	const fileName = "/home/projects/p/src/index.ts"
-	// "😀" is 4 UTF-8 bytes and 2 UTF-16 code units.
-	const content = "const emoji = \"😀\";\nconst x: number = \"oops\";\n"
-	session, snapshot, project := setupFormatSession(t, map[string]any{
-		"/home/projects/p/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
-		fileName:                         content,
-	}, fileName)
-	ctx := context.Background()
-
-	diags, err := session.handleGetSemanticDiagnostics(ctx, &GetDiagnosticsParams{
-		Snapshot: snapshot, Project: project, Files: []DocumentIdentifier{{FileName: fileName}},
-	})
-	assert.NilError(t, err)
-	assert.Equal(t, len(diags), 1)
-
-	plain, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, diags), false)
-	assert.NilError(t, err)
-	assert.Equal(t, plain.Output,
-		"home/projects/p/src/index.ts(2,7): error TS2322: Type 'string' is not assignable to type 'number'.\n")
-
-	color, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, diags), true)
-	assert.NilError(t, err)
-	assert.Assert(t, strings.Contains(color.Output, "const x: number = \"oops\";"))
-	assert.Assert(t, strings.Contains(color.Output, "~"))
-}
-
-func TestFormatDiagnosticsMessageChainAndRelatedInformation(t *testing.T) {
-	t.Parallel()
-	if !bundled.Embedded {
-		t.Skip("bundled files are not embedded")
-	}
-
-	const fileName = "/home/projects/p/src/index.ts"
-	const content = "interface Props { callback: (x: string) => void }\nconst p: Props = { callback: (x: number) => {} };\n"
-	session, snapshot, project := setupFormatSession(t, map[string]any{
-		"/home/projects/p/tsconfig.json": `{ "compilerOptions": { "strict": true } }`,
-		fileName:                         content,
-	}, fileName)
-	ctx := context.Background()
-
-	diags, err := session.handleGetSemanticDiagnostics(ctx, &GetDiagnosticsParams{
-		Snapshot: snapshot, Project: project, Files: []DocumentIdentifier{{FileName: fileName}},
-	})
-	assert.NilError(t, err)
-	assert.Equal(t, len(diags), 1)
-	assert.Assert(t, len(diags[0].MessageChain) > 0, "expected a message chain")
-	assert.Assert(t, len(diags[0].RelatedInformation) > 0, "expected related information")
-
-	color, err := session.handleFormatDiagnostics(ctx, formatDiagnosticsParams(snapshot, project, diags), true)
-	assert.NilError(t, err)
-	assert.Assert(t, strings.Contains(color.Output, "is not assignable to type"))
-	assert.Assert(t, strings.Contains(color.Output, "Types of parameters 'x' and 'x' are incompatible."))
-	assert.Assert(t, strings.Contains(color.Output, "The expected type comes from property 'callback'"))
-}
diff --git a/tsc/internal/diagnosticwriter/diagnosticwriter.go b/tsc/internal/diagnosticwriter/diagnosticwriter.go
index 7abd29ad063c7..b4d00fafa2835 100644
--- a/tsc/internal/diagnosticwriter/diagnosticwriter.go
+++ b/tsc/internal/diagnosticwriter/diagnosticwriter.go
@@ -245,48 +245,6 @@ func FormatDiagnosticWithColorAndContext(output io.Writer, diagnostic Diagnostic
 	}
 }
 
-func FormatDiagnosticsWithColorAndContextForAPI(output io.Writer, diags []Diagnostic, formatOpts *FormattingOptions) {
-	for _, diagnostic := range diags {
-		formatDiagnosticWithColorAndContextForAPI(output, diagnostic, formatOpts)
-	}
-}
-
-func formatDiagnosticWithColorAndContextForAPI(output io.Writer, diagnostic Diagnostic, formatOpts *FormattingOptions) {
-	if diagnostic.File() != nil {
-		file := diagnostic.File()
-		pos := diagnostic.Pos()
-		WriteLocation(output, file, pos, formatOpts, writeWithStyleAndReset)
-		fmt.Fprint(output, " - ")
-	}
-
-	writeWithStyleAndReset(output, diagnostic.Category().Name(), getCategoryFormat(diagnostic.Category()))
-	fmt.Fprintf(output, "%s %s%d: %s", foregroundColorEscapeGrey, diagnosticPrefix(diagnostic), diagnostic.Code(), resetEscapeSequence)
-	WriteFlattenedDiagnosticMessage(output, diagnostic, formatOpts.NewLine, formatOpts.Locale)
-
-	if diagnostic.File() != nil && diagnostic.Code() != diagnostics.File_appears_to_be_binary.Code() {
-		fmt.Fprint(output, formatOpts.NewLine)
-		writeCodeSnippet(output, diagnostic.File(), diagnostic.Pos(), diagnostic.Len(), getCategoryFormat(diagnostic.Category()), "", formatOpts)
-	}
-
-	if len(diagnostic.RelatedInformation()) > 0 {
-		fmt.Fprint(output, formatOpts.NewLine)
-		for _, relatedInformation := range diagnostic.RelatedInformation() {
-			file := relatedInformation.File()
-			if file != nil {
-				fmt.Fprint(output, formatOpts.NewLine)
-				fmt.Fprint(output, "  ")
-				pos := relatedInformation.Pos()
-				WriteLocation(output, file, pos, formatOpts, writeWithStyleAndReset)
-				writeCodeSnippet(output, file, pos, relatedInformation.Len(), foregroundColorEscapeCyan, "    ", formatOpts)
-			}
-			fmt.Fprint(output, formatOpts.NewLine)
-			fmt.Fprint(output, "    ")
-			WriteFlattenedDiagnosticMessage(output, relatedInformation, formatOpts.NewLine, formatOpts.Locale)
-		}
-	}
-	fmt.Fprint(output, formatOpts.NewLine)
-}
-
 func writeCodeSnippet(writer io.Writer, sourceFile FileLike, start int, length int, squiggleColor string, indent string, formatOpts *FormattingOptions) {
 	firstLine, firstLineChar := scanner.GetECMALineAndUTF16CharacterOfPosition(sourceFile, start)
 	lastLine, lastLineChar := scanner.GetECMALineAndUTF16CharacterOfPosition(sourceFile, start+length)
diff --git a/tsc/internal/tsoptions/tsconfigparsing.go b/tsc/internal/tsoptions/tsconfigparsing.go
index 32e89b5070a5b..6f4db55f300fe 100644
--- a/tsc/internal/tsoptions/tsconfigparsing.go
+++ b/tsc/internal/tsoptions/tsconfigparsing.go
@@ -21,7 +21,6 @@ import (
 	"github.com/microsoft/TypeScript/tsc/internal/tspath"
 	"github.com/microsoft/TypeScript/tsc/internal/vfs"
 	"github.com/microsoft/TypeScript/tsc/internal/vfs/vfsmatch"
-	"github.com/zeebo/xxh3"
 )
 
 type extendsResult struct {
@@ -299,7 +298,6 @@ func NewTsconfigSourceFileFromFilePath(configFileName string, configPath tspath.
 		FileName: configFileName,
 		Path:     configPath,
 	}, configSourceText, core.ScriptKindJSON)
-	sourceFile.Hash = xxh3.Hash128([]byte(configSourceText))
 	return &TsConfigSourceFile{
 		SourceFile: sourceFile,
 	}