From 33271abbbb1eaa6c4602c17a06fe7edadb79be4d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Efe=20G=C3=B6kdemir?= <gokdemirefe1903@gmail.com>
Date: Sun, 18 Oct 2026 11:54:24 +0300
Subject: [PATCH] fix(vscode): handle ESM Prettier config

---
 .changeset/tidy-config-loads.md               |  5 ++
 .../src/node/formatter.spec.ts                | 46 +++++++++++++++++++
 .../vscode-extension/src/node/formatter.ts    | 38 ++++++++++++++-
 3 files changed, 87 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/tidy-config-loads.md

diff --git a/.changeset/tidy-config-loads.md b/.changeset/tidy-config-loads.md
new file mode 100644
index 000000000..45b6ca194
--- /dev/null
+++ b/.changeset/tidy-config-loads.md
@@ -0,0 +1,5 @@
+---
+'theme-check-vscode': patch
+---
+
+The VS Code formatter now supports ESM Prettier config exports and falls back with a warning when a config cannot be loaded.
diff --git a/packages/vscode-extension/src/node/formatter.spec.ts b/packages/vscode-extension/src/node/formatter.spec.ts
index a8282814e..dce154e3c 100644
--- a/packages/vscode-extension/src/node/formatter.spec.ts
+++ b/packages/vscode-extension/src/node/formatter.spec.ts
@@ -1,4 +1,5 @@
 import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { window } from 'vscode';
 import type * as vscode from 'vscode';
 import * as prettier from 'prettier';
 import { vscodePrettierFormat, nodePrettierFormat } from './formatter';
@@ -15,6 +16,9 @@ vi.mock('vscode', () => ({
       uri: { fsPath: '/workspace' },
     })),
   },
+  window: {
+    showWarningMessage: vi.fn(),
+  },
 }));
 
 describe('formatter', () => {
@@ -48,11 +52,17 @@ describe('formatter', () => {
     });
 
     it('should format local files with config options', async () => {
+      vi.mocked(prettier.getFileInfo).mockResolvedValue({
+        ignored: false,
+      } as prettier.FileInfoResult);
+      vi.mocked(prettier.resolveConfig).mockResolvedValue({ liquidSingleQuote: false });
+
       await vscodePrettierFormat(localFile);
 
       expect(prettier.getFileInfo).toHaveBeenCalled();
       expect(prettier.resolveConfig).toHaveBeenCalled();
       expect(prettier.format).toHaveBeenCalledWith('<div>{{ product.title }}</div>', {
+        liquidSingleQuote: false,
         parser: 'liquid-html',
         plugins: [expect.anything()],
       });
@@ -70,5 +80,41 @@ describe('formatter', () => {
       expect(prettier.format).not.toHaveBeenCalled();
       expect(result).toBe('<div>{{ product.title }}</div>');
     });
+
+    it('should unwrap ESM Prettier config exports', async () => {
+      vi.mocked(prettier.getFileInfo).mockResolvedValue({
+        ignored: false,
+      } as prettier.FileInfoResult);
+      const esmConfig = { default: { liquidSingleQuote: false } } as unknown as prettier.Options;
+      Object.defineProperty(esmConfig, '__esModule', { value: true });
+      vi.mocked(prettier.resolveConfig).mockResolvedValue(esmConfig);
+
+      await nodePrettierFormat(localFile);
+
+      expect(prettier.format).toHaveBeenCalledWith('<div>{{ product.title }}</div>', {
+        liquidSingleQuote: false,
+        parser: 'liquid-html',
+        plugins: [expect.anything()],
+      });
+      expect(window.showWarningMessage).not.toHaveBeenCalled();
+    });
+
+    it('should fall back to default options when the Prettier config cannot be loaded', async () => {
+      vi.mocked(prettier.getFileInfo).mockResolvedValue({
+        ignored: false,
+      } as prettier.FileInfoResult);
+      vi.mocked(prettier.resolveConfig).mockRejectedValue(new Error('Unsupported ESM config'));
+      vi.mocked(prettier.format).mockReturnValue('formatted');
+
+      const result = await nodePrettierFormat(localFile);
+      await nodePrettierFormat(localFile);
+
+      expect(result).toBe('formatted');
+      expect(prettier.format).toHaveBeenCalledWith('<div>{{ product.title }}</div>', {
+        parser: 'liquid-html',
+        plugins: [expect.anything()],
+      });
+      expect(window.showWarningMessage).toHaveBeenCalledTimes(1);
+    });
   });
 });
diff --git a/packages/vscode-extension/src/node/formatter.ts b/packages/vscode-extension/src/node/formatter.ts
index b1685e011..e06ec7904 100644
--- a/packages/vscode-extension/src/node/formatter.ts
+++ b/packages/vscode-extension/src/node/formatter.ts
@@ -1,9 +1,11 @@
 import path from 'node:path';
-import { workspace } from 'vscode';
+import { window, workspace } from 'vscode';
 import LiquidPrettierPlugin from '@shopify/prettier-plugin-liquid';
 import * as prettier from 'prettier';
 import { Format } from '../common/formatter';
 
+const warnedConfigFolders = new Set<string>();
+
 export const vscodePrettierFormat: Format = async (textDocument) => {
   if (textDocument.uri.scheme === 'file') {
     return nodePrettierFormat(textDocument);
@@ -32,10 +34,42 @@ export const nodePrettierFormat: Format = async (textDocument) => {
     return text;
   }
 
-  const options = await prettier.resolveConfig(textDocument.uri.fsPath, { useCache: false });
+  const warningScope = workspaceFolder?.uri.fsPath ?? path.dirname(textDocument.uri.fsPath);
+  let options: prettier.Options | null;
+  try {
+    options = await prettier.resolveConfig(textDocument.uri.fsPath, { useCache: false });
+    warnedConfigFolders.delete(warningScope);
+  } catch (error) {
+    console.error('Could not load the Prettier configuration; using default options.', error);
+    options = null;
+
+    if (!warnedConfigFolders.has(warningScope)) {
+      warnedConfigFolders.add(warningScope);
+      void window.showWarningMessage(
+        'Could not load the Prettier configuration. Formatting with default options.',
+      );
+    }
+  }
+
+  options = unwrapPrettierConfig(options);
   return prettier.format(text, {
     ...options,
     parser: 'liquid-html',
     plugins: [LiquidPrettierPlugin as any],
   });
 };
+
+function unwrapPrettierConfig(options: prettier.Options | null): prettier.Options | null {
+  const moduleConfig = options as (prettier.Options & Record<string, unknown>) | null;
+  const defaultConfig = moduleConfig?.default;
+
+  if (
+    moduleConfig?.['__esModule'] === true &&
+    defaultConfig !== null &&
+    typeof defaultConfig === 'object'
+  ) {
+    return defaultConfig as prettier.Options;
+  }
+
+  return options;
+}