fix(core): Treat .mts files as TypeScript modules instead of video files (#5492)

Co-authored-by: Jacob Richman <[email protected]>

2 files changed, 9 insertions, 4 deletions

diff --git a/packages/core/src/utils/fileUtils.test.ts b/packages/core/src/utils/fileUtils.test.ts
index bcdf3fe7..fb6b6820 100644
--- a/packages/core/src/utils/fileUtils.test.ts
+++ b/packages/core/src/utils/fileUtils.test.ts
@@ -196,9 +196,13 @@ describe('fileUtils', () => {
       vi.restoreAllMocks(); // Restore spies on actualNodeFs
     });
 
-    it('should detect typescript type by extension (ts)', async () => {
+    it('should detect typescript type by extension (ts, mts, cts, tsx)', async () => {
       expect(await detectFileType('file.ts')).toBe('text');
       expect(await detectFileType('file.test.ts')).toBe('text');
+      expect(await detectFileType('file.mts')).toBe('text');
+      expect(await detectFileType('vite.config.mts')).toBe('text');
+      expect(await detectFileType('file.cts')).toBe('text');
+      expect(await detectFileType('component.tsx')).toBe('text');
     });
 
     it('should detect image type by extension (png)', async () => {
diff --git a/packages/core/src/utils/fileUtils.ts b/packages/core/src/utils/fileUtils.ts
index 96f4b36c..a153d205 100644
--- a/packages/core/src/utils/fileUtils.ts
+++ b/packages/core/src/utils/fileUtils.ts
@@ -122,9 +122,10 @@ export async function detectFileType(
 ): Promise<'text' | 'image' | 'pdf' | 'audio' | 'video' | 'binary' | 'svg'> {
   const ext = path.extname(filePath).toLowerCase();
 
-  // The mimetype for "ts" is MPEG transport stream (a video format) but we want
-  // to assume these are typescript files instead.
-  if (ext === '.ts') {
+  // The mimetype for various TypeScript extensions (ts, mts, cts, tsx) can be
+  // MPEG transport stream (a video format), but we want to assume these are
+  // TypeScript files instead.
+  if (['.ts', '.mts', '.cts'].includes(ext)) {
     return 'text';
   }