[juliusmarminge]

Windows drive paths in mobile messages lose their backslashes before punctuation, so C:\Users\me\.t3\_build\shot.png displays as C:\Users\me.t3_build\shot.png. CommonMark reads each \. or \_ as an escape.

The native fix now lives in our Enriched Markdown fork and is going upstream, not in a pnpm patch:

• Upstream: software-mansion/enriched-markdown#1105 adds an opt-in md4cFlags.preserveWindowsPaths. It needs software-mansion-labs/md4c#5, an opt-in ENRMRKD_TEXT_ESCAPED that lets the wrapper tell \. from ., because Enriched Markdown vendors md4c unchanged.
• Fork: pingdotgg/enriched-markdown#10 cherry-picks the upstream commit onto fork/t3-mobile and rebuilds the web bundle. Merge it together with this PR.
• T3 Code: ships the archive packed from fork commit 4b18620c and turns the flag on in the mobile renderer. The pnpm patch, its patchedDependencies/allowBuilds entries, and the build-script workaround are gone.

The JS document parser (PR descriptions, image sources) keeps prose paths too, through a prose-only remarkKeepWindowsProsePaths split out of the shared plugin. #25802 already escapes Windows destinations before both mobile parsers, so the prose-only plugin skips buffered destinations, titles and labels. Web keeps using the full plugin and behaves as before.

Rebuilds the remaining mobile part of #15582, with credit to OhadC.

Verification:

• Native parser, from the upstream golden AST fixture:

  flag off: Saved to C:\Users\me.t3_build\shot.png and C:/work.config and C:\folder(draft.
  flag on:  Saved to C:\Users\me\.t3\_build\shot.png and C:/work\.config and C:\folder\(draft.
  

  Ordinary escapes after whitespace, code spans, link destinations/titles and image alt text are unchanged. The upstream core parser and web-bundle checks pass, and no existing fixture's AST changed.
• One mobile regression test for prose paths. It fails on main and passes here. Mobile src/lib (704 tests), shared markdown and web ChatMarkdown suites pass, and so does vp run check:changed.
• Both native dev clients were built from source for this fingerprint: iOS simulator (installed on an iPhone 17 Pro simulator) and Android. The iOS build caught a missing codegen field in the fork; it's fixed upstream and in the archive. I did not check the rendered message visually on a device.

Needs rebuilt native clients; a JS OTA alone does not carry the native change.

Model: Claude Opus 5.5. Harness: Claude Code in T3 Code.

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	5.0 KiB	5.0 KiB	+6 B (+0.1%)	6.8 KiB	✅
Codex	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Codex	Live turn WebSocket wire	1.2 KiB	1.3 KiB	+6 B (+0.5%)	2.0 KiB	✅
Codex	Live turn WebSocket decoded	21.6 KiB	21.6 KiB	0 B (0.0%)	24.4 KiB	✅
Codex	Live turn messages	2	2	0 (0.0%)	8	✅
Claude	Total thread wire	5.0 KiB	5.0 KiB	0 B (0.0%)	6.8 KiB	✅
Claude	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Claude	Live turn WebSocket wire	1.3 KiB	1.3 KiB	0 B (0.0%)	2.0 KiB	✅
Claude	Live turn WebSocket decoded	21.9 KiB	21.9 KiB	0 B (0.0%)	24.4 KiB	✅
Claude	Live turn messages	2	2	0 (0.0%)	8	✅

Baseline: b88da91 · PR result: 7edcc0e · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 108.5 KiB
• Claude decoded thread snapshot: 108.8 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.

[macroscopeapp]

Approvability

Verdict: Needs Human Approval

Macroscope's review found this PR requires human approval — Windows drive paths will retain their backslashes in mobile Markdown by default. This changes existing rendering behavior without user opt-in and requires human confirmation.

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Walkthrough

The shared Markdown pipeline and mobile parser now preserve Windows drive paths during parsing. A native parser patch handles escaped punctuation in those paths. Tests cover paths in prose, code, links, images, and reference syntax.

Changes: Windows Drive-Path Parsing

Layer / File(s)	Summary
Extract and wire the shared remark plugin packages/shared/src/markdownWindowsPaths.ts, packages/shared/src/markdownPipeline.ts, packages/shared/package.json, packages/shared/src/markdownPipeline.test.ts	The shared package exports a remark plugin that preserves Windows drive paths in destinations and prose. The Markdown pipeline uses the plugin, and tests check parsed text, escapes, and code nodes.
Apply path handling in mobile Markdown apps/mobile/src/lib/markdownDocument.ts, apps/mobile/src/lib/markdownHtml.test.ts	The mobile Markdown parser applies the shared plugin after remark-gfm. Tests cover paths in prose, Markdown escapes, code, links, images, titles, and reference syntax.
Preserve paths in native parsing patches/react-native-enriched-markdown@1.2.0-t3.15.patch, pnpm-workspace.yaml, apps/mobile/deps/README.md, scripts/build-desktop-artifact.test.ts	The native parser patch identifies escaped punctuation and restores backslashes within Windows drive paths. The workspace registers the patch, and the README documents its retention and rebuild requirements. The desktop artifact test strips pnpm patch-hash suffixes from tarball keys before checking the referenced path.

Priority: Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

Suggested reviewers: t3dotgg

Merge Risk: Minimal · previous review 90b75

Mobile Markdown aims to preserve backslashes in Windows paths. The reviewed change only normalizes the patched-tarball key for an existence check, and the referenced tarball is present in a clean checkout; no concrete merge-blocking risk was found.

Pre-merge checks: 4

Check name	Status	Explanation
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Title check		The title clearly and concisely describes the main change: preserving backslashes in Windows paths in mobile messages.
Description check		The description covers the problem, implementation, scope, native-client requirement, and focused verification. It does not clearly provide explicit maintainer approval or explain an approval exemptio…

Full details: Description check

Explanation

The description covers the problem, implementation, scope, native-client requirement, and focused verification. It does not clearly provide explicit maintainer approval or explain an approval exemption, but it links the related upstream and fork work and is otherwise mostly complete.

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Inline comments:
Review comments at @apps/mobile/deps/README.md:
- Line 5: Update the Enriched Markdown tarball replacement steps to include
changing the exact-version patchedDependencies key from 1.2.0-t3.15 to the
replacement version, and verify that the patch applies during installation.

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• packages/shared/src/markdownPipeline.test.ts
• packages/shared/src/markdownPipeline.ts
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