docs(mobile): record agent conventions for tests, variants, and file modules

[juliusmarminge]

The problem

apps/mobile has no AGENTS.md (the repository root has the only one, and CLAUDE.md is just @AGENTS.md), so agents relearn the same small mobile conventions from scratch: the Node-environment test setup and vi.mock pattern, the @effect/vitest / vite-plus/test split, Platform.OS vs file-variant divergence, naming, relative imports, and the pnpm file: module reinstall gotcha.

The fix

A short, factual apps/mobile/AGENTS.md. This is now an ordinary single-commit PR against current main (68607c5); #13150 was closed unmerged, so all renderer/test-host guidance was removed and every statement was re-verified against origin/main:

• Tests: vp test run uses the repository-root Vitest config (test.environment: "node"; focused runs report environment 0ms). On main, 33 files under src import @effect/vitest (13 mixing it with vite-plus/test for vi), 160 use vite-plus/test, and only the standalone .mjs config-plugin test under plugins/ imports vitest. The vi.hoisted + vi.mock + import-under-test-after pattern matches existing files. The two .test.tsx files under src render via renderToStaticMarkup with react-native mocked — recorded as what exists, and the doc says to follow a local modules/* package's own setup there (e.g. react-dom/client + DOM shims in t3-markdown-text).
• Platform divergence: styling differences use Platform.OS className branches. Uniwind ios:/android: class variants are documented as must-not-use: unguarded in this repo's Metro pipeline (Android classes apply on iOS and vice versa); revert(mobile): git sheets back to Platform.OS ternaries (un-guarded uniwind variants broke both platforms) #13169 reverted refactor(mobile): git sheets use uniwind platform variants instead of className ternaries #13161 (ec28eefa0d0) for exactly this reason, and the ban stands until the pipeline is fixed/upgraded and platform isolation is proved on both devices. Verified on current main: the revert removed the git-sheet usages, but a few remain in src (settings rows/screens, NewTaskDraftScreen, worktree-setup-card); the doc states they still leak, need remediation, and no more should be added. Behavior differences branch on Platform.OS; file variants (.ios/.android/.native over the extensionless base, Name.shared.tsx re-export per AndroidHomeFab) for wholesale UI differences.
• Naming: 28 *RouteScreen.tsx files, PascalCase components vs kebab-case logic modules; hook files split roughly evenly between useCamelCase.ts and use-kebab-case.ts, so the doc says to match the surrounding directory.
• Imports: no @/ alias or baseUrl in apps/mobile/tsconfig.json (zero @/ imports in src); @t3tools/client-runtime has no root export and a root lint rule (RESTRICTED_IMPORT_PATHS in vite.config.ts) forces explicit subpaths.
• file: modules: restates the existing explanation in docs/internals/mobile-development.md (pnpm copies modules/*; edit → vp i before Metro sees it) instead of re-deriving it.

The earlier docs/internals/mobile-navigation.md audit item did not reproduce: all six links and the README.md#development anchor resolve on main, the three cited Swift media-presentation files exist under t3-native-controls/ios/ (which is where the AVKit/Quick Look implementations live; t3-markdown-text has no Swift at all), so that file is unchanged.

No runtime code touched. Screenshots n/a (docs only).

Verification

• vp test run src/features/home/thread-dismissal.test.ts → 4 passed (environment 0ms, confirming the documented Node environment)
• vp test run src/native/voiceTranscription.ios.test.ts → 4 passed (confirms the platform-variant test convention)
• Docs-only change; commit hooks ran vp fmt clean.

Model: callstack/Apex via pi (T3 Code).

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — The requested range includes substantial authentication and credential-flow changes, new RPC/schema and session-management behavior, production settings changes for project defaults, and other runtime UI changes—not only documentation. Sensitive auth changes and the product-default change require human review, with an unresolved documentation finding also present.

Not approved because:

• 1 blocking correctness issue found at or above your repo's Minimum Blocking Severity

^{Adjust the Minimum Blocking Severity for this repo — including turning it Off — in Settings. You can add or adjust custom eligibility rules. Learn more.}

[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	13.5 KiB	13.5 KiB	+13 B (+0.1%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.1 KiB	7.1 KiB	+3 B (+0.0%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.5 KiB	6.5 KiB	+10 B (+0.2%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	56.3 KiB	56.3 KiB	0 B (0.0%)	66.4 KiB	✅
Codex	Live turn messages	10	10	0 (0.0%)	21	✅
Claude	Total thread wire	13.5 KiB	13.5 KiB	0 B (0.0%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.1 KiB	7.1 KiB	−2 B (−0.0%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.4 KiB	6.4 KiB	+2 B (+0.0%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	57.0 KiB	57.0 KiB	0 B (0.0%)	66.4 KiB	✅
Claude	Live turn messages	9	9	0 (0.0%)	21	✅

Baseline: b954af6 · PR result: 17f9a12 · 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: 114.0 KiB
• Claude decoded thread snapshot: 114.6 KiB

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📝 Walkthrough

Walkthrough

Added mobile development guidance for testing, validation, file organization, platform variants, imports, and copied file: dependencies.

Changes

Mobile development guidance

Layer / File(s)	Summary
Mobile testing and development workflow apps/mobile/AGENTS.md	Documents Vitest testing, native and Expo fakes, validation commands, platform-specific behavior, naming and directory conventions, import rules, and reinstalling copied file: dependencies after TypeScript edits.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~4 minutes

Change: Other

Merge Risk: ⚪ Minimal · up to 17f9a

The documented import example does not vary by test directory depth, so the previously identified path-resolution risk is not present.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
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.
Title check	✅ Passed	The title clearly identifies the documentation change and the mobile conventions it records. It is concise and related to the main change.
Description check	✅ Passed	The description clearly explains the problem, the documentation fix, scope, verification, and why UI screenshots are not applicable. It does not use the template headings or include the checklist, but…

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Actionable comments posted: 1

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Inline comments:
In `@apps/mobile/AGENTS.md`:
- Around line 32-33: Update the vi.mock guidance for react-native and
react-native-reanimated to clarify that their relative host imports resolve from
each importing test file; state the expected test-file location or instruct
readers to adjust each relative path accordingly.

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[juliusmarminge]

Superseded by #13173. #13150 was closed unmerged, so this docs PR was re-scoped to facts on current main (react-test-renderer/test-host guidance removed). GitHub kept this PR head pinned at 17f9a12 after the force-push collided with the base retarget (branch ref is 8593dee), so the work continues as a fresh PR from the same branch rather than fighting the stale ref. Review history and thread resolutions stay here.