QLTextView

QuickLook Text Viewer for multiple files types

Known limitations

.ts files are not previewed

TypeScript source files (.ts) collide with MPEG-2 transport-stream video, which macOS binds to the .ts extension system-wide as public.mpeg-2-transport-stream. Quick Look then routes the file to the legacy /System/Library/QuickLook/Movie.qlgenerator, which claims the parent type public.movie. That generator wins selection over our app extension, fails to produce a preview for what is actually text, and Quick Look does not fall through to other candidates — so the file shows the generic "no preview" panel.

There is no clean third-party workaround:

• A third-party app cannot override the system's .ts → public.mpeg-2-transport-stream UTI binding. We declare .ts in the host app's UTExportedTypeDeclarations, but mdls confirms the file still resolves to public.mpeg-2-transport-stream.
• Declaring public.mpeg-2-transport-stream in the extension's QLSupportedContentTypes doesn't help either — Movie.qlgenerator beats our app extension on the routing.
• Disabling Movie.qlgenerator system-wide would require disabling SIP and would break Quick Look for genuine video files.

The relevant declarations are left in place (public.mpeg-2-transport-stream in QLTextViewExtension/Info.plist, ts in the UTExportedTypeDeclarations filename-extension list, and ts in TextDetection.defaultExtensions) so that if Apple retires Movie.qlgenerator — it has long been deprecated — .ts previews will start working without a code change.

File size cap

Files larger than 100 KB are previewed truncated, ending with a [truncated — file exceeds 100 KB preview limit] notice. The cap is TextDetection.defaultMaxBytes.