feat(mobile): make chat text selectable on Android

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Android chat messages could only use the whole-message copy action. Long-press selection was unavailable because the Android entry point disabled the existing selectable Markdown renderer.

This enables that renderer on Android for both user and agent messages. The renderer already falls back to React Native selectable Text outside iOS, so Markdown stays chunked around rich blocks while Android supplies its native selection handles and Copy/Share/Select all menu. Code spans and blocks now choose Android's monospace family instead of the iOS-only ui-monospace name.

Verification

• pnpm exec vp lint apps/mobile/src/native/SelectableMarkdownText.android.tsx apps/mobile/modules/t3-markdown-text/src/NativeMarkdownSelectableText.ios.tsx apps/mobile/modules/t3-markdown-text/src/NativeMarkdownBlock.ios.tsx
• pnpm --filter @t3tools/mobile typecheck
• pnpm exec vp test run apps/mobile/src/lib/nativeMarkdownText.test.ts apps/mobile/src/features/threads/markdownImageSize.test.ts (37 tests)
• pnpm --filter @t3tools/mobile exec expo export --platform android
• Pixel 9 Pro Android 16/API 36 emulator: native range selection confirmed in both message roles
• Galaxy S25 Ultra Android 16/API 36: fresh native build installed and file-icon range copied into the composer without U+FFFC
• Android UI dump after paste: selected text was media labels\n\nOpen README.md; no object-replacement character remained

Android emulator evidence

User message	Agent Markdown

Galaxy S25 Ultra copy evidence

Built with GPT-5.6-sol through the Codex harness in T3 Code.

---

Note

Medium Risk
Touches chat rendering and clipboard behavior on Android via a new native module and platform branches in shared markdown code; scope is localized but user-visible copy/selection regressions are possible.

Overview
Enables long-press text selection for chat Markdown on Android by adding a platform SelectableMarkdownText entry that routes through the shared renderer (with Shiki highlighting), so ThreadFeed and similar callers that gate on hasNativeSelectableMarkdownText() now get native selection handles instead of whole-message copy only.

Android-specific rendering and clipboard behavior in the markdown module: file links render as inline Image children (not iOS object-replacement placeholders), skill chips show as $skillName, and code uses a platform MONO_FONT_FAMILY. A new Expo Android module hooks each relevant TextView's selection action mode so Copy strips U+FFFC / inline-image replacement spans from the clipboard; JS installs it via a new nativeTextRef on MarkdownTextPrimitive. Horizontal code-block and table scroll views turn on nestedScrollEnabled on Android.

Package metadata adds the Android native sources and an expo peer dependency for the optional native module loader.

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Note

Make chat text selectable on Android with sanitized copy

• Adds an Android SelectableMarkdownText entrypoint that renders through the shared markdown renderer with highlightCodeSnippet injected as the code highlighter
• Adds an Expo native module (T3MarkdownTextSelectionModule) that wraps a TextView's selection callback so copied text strips inline-image replacement characters from Spanned selections
• Renders file icons as inline Image children on Android (instead of the iOS object-replacement placeholder) and skills as dollar-prefixed names; installs the copy sanitizer on text views containing file icons
• Switches hardcoded ui-monospace to a platform-selected MONO_FONT_FAMILY constant and enables nestedScrollEnabled on horizontal ScrollViews for code blocks and tables on Android
• Behavioral Change: Android selectable markdown now uses inline images for file icons and a sanitizing copy callback; native IDs for file/skill icons are emitted only on iOS

^{Macroscope summarized d3e1d62.}

Summary by CodeRabbit

• New Features

  • Added native selectable Markdown text support on Android.
  • Added syntax highlighting for code blocks in selectable Markdown content.
  • Improved rendering of file icons and skill labels across platforms.

• Improvements

  • Copied Markdown selections on Android are now cleaned up for easier reuse.
  • Updated code blocks to use platform-appropriate monospace fonts.
  • Improved scrolling behavior for code blocks and tables on Android.

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📝 Walkthrough

Walkthrough

The mobile markdown renderer adds Android selectable markdown with Shiki highlighting and copy sanitization. Native markdown components now select platform-specific monospace fonts, enable Android nested scrolling, and adjust inline file and skill rendering by platform.

Changes

Native markdown rendering

Layer / File(s)	Summary
Enable Android selectable markdown apps/mobile/src/native/SelectableMarkdownText.android.tsx	The Android wrapper renders selectable markdown with highlightCodeSnippet, reports native support, and re-exports related markdown types.
Sanitize Android selectable text apps/mobile/modules/t3-markdown-text/android/*, apps/mobile/modules/t3-markdown-text/src/T3MarkdownTextSelectionModule.ts, apps/mobile/modules/t3-markdown-text/src/NativeMarkdownSelectableText.ios.tsx, apps/mobile/modules/t3-markdown-text/src/MarkdownTextPrimitive.tsx, apps/mobile/modules/t3-markdown-text/src/package.json	The Android Expo module removes object replacement characters from copied selections. The selectable renderer passes a native text ref and installs the sanitizer when inline file icons are present.
Select platform monospace fonts apps/mobile/modules/t3-markdown-text/src/NativeMarkdownBlock.ios.tsx, apps/mobile/modules/t3-markdown-text/src/NativeMarkdownSelectableText.ios.tsx	Code, highlighted token, and language-label styles use ui-monospace on iOS and monospace on Android or other platforms.
Adjust platform-specific scrolling and inline content apps/mobile/modules/t3-markdown-text/src/NativeMarkdownBlock.ios.tsx, apps/mobile/modules/t3-markdown-text/src/NativeMarkdownSelectableText.ios.tsx	Code and table scroll views enable nested scrolling on Android. File-icon prefixes, native IDs, skill labels, and inline file images vary by platform.

Estimated code review effort: 3 (Moderate) | ~25 minutes

Merge Risk: 🟡 Moderate · up to 4f7c4

This PR enables Android text selection and sanitizes copied inline file content, but the new copy behavior currently has no cleanup path when a view no longer needs sanitization. That can leave stale copy handling on reused message views, so merge should wait for lifecycle cleanup or explicit owner acceptance.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 9.52% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 21 functions across 7 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the primary change: enabling selectable chat text on Android.
Description check	✅ Passed	The description explains what changed, why it changed, the Android UI behavior, copy sanitization, verification steps, and UI evidence. It does not use the template headings exactly and omits the chec…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

Full details: Description check

Explanation

The description explains what changed, why it changed, the Android UI behavior, copy sanitization, verification steps, and UI evidence. It does not use the template headings exactly and omits the checklist, but it provides the required information and is mostly complete.

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Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This PR enables a new default Android Markdown rendering and selection path for existing chat messages, including native TextView clipboard handling, inline image behavior, and rich-block scrolling. The cross-platform renderer changes and production native-module integration warrant human review.

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Actionable comments posted: 1

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Inline comments:
In
`@apps/mobile/modules/t3-markdown-text/android/src/main/java/expo/modules/t3markdowntext/T3MarkdownTextSelectionModule.kt`:
- Line 21: Fix the Ktlint violations in the T3MarkdownTextSelectionModule
declaration and resolveView call: remove the trailing comma after the delegate
parameter and normalize the indentation of the wrapped resolveView arguments.

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📒 Files selected for processing (7)

• apps/mobile/modules/t3-markdown-text/android/build.gradle
• apps/mobile/modules/t3-markdown-text/android/src/main/java/expo/modules/t3markdowntext/T3MarkdownTextSelectionModule.kt
• apps/mobile/modules/t3-markdown-text/expo-module.config.json
• apps/mobile/modules/t3-markdown-text/package.json
• apps/mobile/modules/t3-markdown-text/src/MarkdownTextPrimitive.tsx
• apps/mobile/modules/t3-markdown-text/src/NativeMarkdownSelectableText.ios.tsx
• apps/mobile/modules/t3-markdown-text/src/T3MarkdownTextSelectionModule.ts

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Actionable comments posted: 1

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Inline comments:
In
`@apps/mobile/modules/t3-markdown-text/android/src/main/java/expo/modules/t3markdowntext/T3MarkdownTextSelectionModule.kt`:
- Line 76: Add cleanup and installation-state operations alongside
installCopySanitizer, using the same reactTag-to-TextView lookup and callback
tracking to restore the original customSelectionActionModeCallback, report
whether sanitization is installed, and invoke cleanup when the view no longer
requires sanitization.

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Cursor Bugbot has reviewed your changes using default effort and found 1 potential issue.

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Share still exports image markers

Medium Severity

The sanitizer only handles the action-mode copy item. Share from the same toolbar, and other onTextContextMenuItem copy paths, still export the inline-image U+FFFC marker that this module exists to strip.

 

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