From 050804001d356266d13f56829ed1c3a0f173ddbc Mon Sep 17 00:00:00 2001
From: Shaurya Singh <sshaurya914@gmail.com>
Date: Wed, 27 May 2026 11:53:17 -0700
Subject: [PATCH] [api-extractor] Surface bundledPackages no-op when packageId
 is missing (#5730)
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When `bundledPackages` is configured but TypeScript could not assign a
`packageId` to a resolved module, the lookup in `_isExternalModulePath`
silently failed via optional chaining and the module was bundled as
external. The most common cause is a local workspace package whose
`package.json` lacks a `"version"` field — TypeScript does not assign
a `packageId` without one (microsoft/TypeScript#63307).

Throw an `InternalError` with a remediation message in that exact
combination (`packageId` undefined AND `_bundledPackageNames.size > 0`)
so users see the cause instead of staring at an unexpectedly-not-bundled
`from "foo"` in their `.d.ts` rollup.

The non-bundled case (`_bundledPackageNames.size === 0`) is unchanged
— the missing `packageId` flows through to the existing
`isExternalLibraryImport` check that already handles ambiguous modules.

Matches the fix suggested by the issue reporter in microsoft/rushstack#5730.
---
 .../src/analyzer/ExportAnalyzer.ts            | 22 +++++++++++++++++++
 ...ages-missing-version_2026-05-27-19-00.json | 10 +++++++++
 2 files changed, 32 insertions(+)
 create mode 100644 common/changes/@microsoft/api-extractor/fix-bundled-packages-missing-version_2026-05-27-19-00.json

diff --git a/apps/api-extractor/src/analyzer/ExportAnalyzer.ts b/apps/api-extractor/src/analyzer/ExportAnalyzer.ts
index 0bc6236aa4d..a8c8326b134 100644
--- a/apps/api-extractor/src/analyzer/ExportAnalyzer.ts
+++ b/apps/api-extractor/src/analyzer/ExportAnalyzer.ts
@@ -309,6 +309,28 @@ export class ExportAnalyzer {
       );
     }
 
+    // If the user configured `bundledPackages` but TypeScript could not produce a `packageId` for this
+    // *external* module, the bundled-package lookup above is guaranteed to miss it and the module will be
+    // silently treated as external (issue #5730). The most common cause is a package whose `package.json`
+    // lacks a `"version"` field, since TypeScript does not assign a `packageId` without one
+    // (microsoft/TypeScript#63307). Surface the cause with a remediable error rather than producing a
+    // confusing bundling result. Internal (relative) imports legitimately have no `packageId`, so this
+    // check is scoped to external library imports only.
+    if (
+      resolvedModule.isExternalLibraryImport &&
+      packageName === undefined &&
+      this._bundledPackageNames.size > 0
+    ) {
+      throw new InternalError(
+        `Cannot determine the package name for the external module ${JSON.stringify(moduleSpecifier)}, ` +
+          `but "bundledPackages" is configured. This is usually because the resolved package's ` +
+          `package.json is missing a "version" field, since TypeScript does not assign a packageId ` +
+          `without one (microsoft/TypeScript#63307), so the bundledPackages lookup cannot match it. ` +
+          `Add a "version" field (any value works) to the package's package.json and re-run.\n` +
+          SourceFileLocationFormatter.formatDeclaration(importOrExportDeclaration)
+      );
+    }
+
     return resolvedModule.isExternalLibraryImport;
   }
 
diff --git a/common/changes/@microsoft/api-extractor/fix-bundled-packages-missing-version_2026-05-27-19-00.json b/common/changes/@microsoft/api-extractor/fix-bundled-packages-missing-version_2026-05-27-19-00.json
new file mode 100644
index 00000000000..44d84268fae
--- /dev/null
+++ b/common/changes/@microsoft/api-extractor/fix-bundled-packages-missing-version_2026-05-27-19-00.json
@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@microsoft/api-extractor",
+      "comment": "Throw an actionable InternalError instead of silently failing to bundle when bundledPackages is configured but TypeScript could not assign a packageId to the resolved module (most often because the package's package.json is missing a \"version\" field).",
+      "type": "patch"
+    }
+  ],
+  "packageName": "@microsoft/api-extractor"
+}
\ No newline at end of file