[Bug]: iOS file viewer can't select text in files without a Preview mode (JSON, YAML, code)#33178

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Related

• #30178 reports the same file-viewer selection problem on Android: selection can't go past a single line.
• PR #31286 fixes #30178. Long-pressing a source line opens the whole file as selectable text. It is limited to Android on purpose (Platform.OS === "android", and its description says "iOS keeps its existing renderer"), so this iOS case stays open after it merges.
• This is likely the same underlying problem on the other platform. Extending #31286's long-press flow to iOS, where SourceFileSurface already has a document-wide selectable text view, would probably fix this too. Happy to fold this into that work rather than a separate fix if maintainers prefer.
• Not the same as #15927, which is about partial copies in the desktop/web Files panel.

Area

apps/mobile

Steps to reproduce

1. In the iOS app, open a workspace file that has no Preview mode, for example a .json file linked from a thread.
2. Long-press or drag over a value to select part of it.
3. Optionally, turn on word wrap from the file's ⋯ menu and repeat.

Expected behavior

Being able to select part of the file's text and copy it, as in Markdown Preview or in chat attachments, for example to copy a single value out of a JSON file.

Actual behavior

• With word wrap off, no text can be selected at all.
• With word wrap on, long-pressing a line shows a Copy menu for that whole line, but there are no selection handles to narrow it to part of the line or extend it across lines.
• The only other option is ⋯ → Copy contents, which copies the whole file.

Markdown files are fine in practice, because switching them to Preview gives selectable text. Files without a Preview mode (JSON, YAML, .env, source code) only have this Source view. It doesn't matter whether the app is connected to a local or a remote server.

Likely cause (reading main at d0f1f7200d):

• SourceFileSurface already supports a selectable mode: a single native text view that allows selection across the whole document, with boundedSelectableSourceTokens keeping highlighting bounded.
• Attachments use it: apps/mobile/src/features/files/AttachmentDocumentBody.tsx:82 passes selectable.
• The workspace file screen doesn't: apps/mobile/src/features/files/ThreadFilesRouteScreen.tsx:311 renders <SourceFileSurface> without selectable. On iOS with word wrap off this picks NativeSourceFileSurface (the native review-diff view), which has no text selection. With word wrap on it uses the virtualized FlatList, where each line is its own selectable Text, which matches the whole-line Copy shown below.

A possible fix is letting the file screen turn on selectable, either from a "Select text" item next to "Copy contents" or automatically for small files. I'm glad to send a small PR if maintainers agree on the direction.

Impact

Minor bug or occasional failure

Version or commit

iOS TestFlight build as of 2026-11-08; server 0.1.6. Code references are from main at d0f1f7200d.

Environment

iPhone (iOS, dark theme), app connected to a remote T3 server.

Logs or stack traces

None, since nothing errors.

Screenshots, recordings, or supporting files

Values and paths in the screenshots are redacted.