fix(mobile): restore file viewer insets and glass header

[juliusmarminge]

Source files could render line 1 behind the native header and leave their final rows against the screen corners. The Files list applied an extra scroll-indicator inset and displayed folder child counts.

Remove the counts, let UIKit adjust the list indicator, and give source files scroll-content insets rather than shrinking their viewport. Use the transparent native header so content scrolls underneath its blur. Native row jumps account for the insets; wrapped and selectable source views use UIKit's automatic adjustment. Truncated files reserve space for their fixed warning below the header. Embedded HTML/Styles previews opt out of screen reservations in both native and wrapped modes.

Scope and approval

Maintainer-requested follow-up to the navigation changes in #16733. Julius reported the folder counts, misplaced scroll indicator, clipped first line, and bottom-corner overlap, then explicitly requested the transparent header and native blur. Scope is limited to those file-viewer fixes and their full-screen, truncated, and embedded variants.

The PR author, juliusmarminge, is explicitly listed in the trusted upstream triage exemptions. This records the existing maintainer request and triage exemption; normal correctness and merge review still apply.

Validation: mobile TypeScript check, 10 focused file-tree/source tests, and Xcode simulator build pass. React Doctor reports one complexity warning in the JavaScript source renderer and no errors. Verified first and last lines, native and wrapped source scrolling, folder-list scrolling, and a real truncated file on iPhone 17 Pro Max, iOS 26.5. All CI jobs that ran passed on ff02e76. Review threads are resolved; CodeRabbit is refreshing its description check.

Same 180-line fixture at rest, native canvas:

Before	After

Recording: transparent at rest, blur during scrolling, then return to rest

Bottom clearance and truncated-file warning

Requires a new native build for the source canvas inset props.

Model: GPT-6.1 Sol. Harness: Codex in T3 Code.

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — The file viewer now uses a glass header by default and changes native and JavaScript scrolling/inset behavior across mobile surfaces. These are user-visible runtime and product-default changes, alongside a native build change, so they warrant human review.

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[coderabbitai]

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 0563347 and ff02e76.

📒 Files selected for processing (2)

• apps/mobile/src/components/ComposerContextSheet.tsx
• apps/mobile/src/features/files/SourceFileSurface.tsx

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📝 Walkthrough

Walkthrough

Mobile file surfaces now support inset-aware native diff scrolling and updated safe-area handling. Embedded surfaces disable their own inset adjustment. File-tree rows no longer use loaded-directory state or display loaded child counts. Thread file screens use glass-header options.

Changes

Mobile file viewers

Layer / File(s)	Summary
Native diff content insets apps/mobile/modules/t3-review-diff/ios/T3ReviewDiffModule.swift, apps/mobile/modules/t3-review-diff/ios/T3ReviewDiffView.swift, apps/mobile/src/features/diffs/nativeReviewDiffSurface.ts	The native diff surface accepts top and bottom content insets. The view applies them to reset, programmatic, and initial-row scroll positioning.
File content inset handling apps/mobile/src/features/files/SourceFileSurface.tsx, apps/mobile/src/features/files/ThreadFilesRouteScreen.tsx, apps/mobile/src/components/ComposerContextSheet.tsx	Source surfaces use native column safe-area metrics when available and accept a top-inset override. Embedded surfaces use zero native insets and disable automatic JavaScript inset adjustment. On iOS, truncated file content reserves top spacing based on the column metric or safe-area inset.
File tree and header updates apps/mobile/src/Stack.tsx, apps/mobile/src/features/files/FileTreeBrowser.tsx, apps/mobile/src/features/files/ThreadFilesRouteScreen.tsx, apps/mobile/src/features/files/thread-file-navigator-pane.tsx	ThreadFile uses glass-header options. The file tree uses native column safe-area metrics for its iOS header inset and automatic scroll-indicator adjustment. Loaded-directory state and child counts are removed from file-tree rows and callers.

Priority: ➖ Normal

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

Change: Bug fix

Suggested reviewers: chrisdeeming

Merge Risk: 🔵 Low · up to ff02e

Some file jumps can show “All files” instead of the selected file, although the content still scrolls into position. This is a bounded navigation-state issue; the change is mergeable with owner awareness, but correcting the selection state is advisable.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
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 summarizes the primary changes: restoring file viewer insets and using the glass header.
Description check	✅ Passed	The description provides the problem, implementation details, scope and approval context, verification results, and required UI evidence. The Problem, Change, and Verification headings are not used ex…

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[coderabbitai]

Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

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Inline comments:
Review comments at
@apps/mobile/modules/t3-review-diff/ios/T3ReviewDiffView.swift:
- Line 896: Update emitVisibleFileIfNeeded() to determine the visible file using
the inset-aware content position rather than treating every offset at or below
0.5 as “All files.” Keep the “All files” state distinct from offsets reached by
scrollToFile, including headers within the top inset.

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ℹ️ Review info

⚙️ Run configuration

• Configuration used: Path: .coderabbit.config.ts
• Review profile: CHILL
• Plan: Team
• Run ID: 8af95db5-41a3-450b-b3e5-e390591589af

📥 Commits

Reviewing files that changed from the base of the PR and between 0bfd9dd and 0563347.

📒 Files selected for processing (8)

• apps/mobile/modules/t3-review-diff/ios/T3ReviewDiffModule.swift
• apps/mobile/modules/t3-review-diff/ios/T3ReviewDiffView.swift
• apps/mobile/src/Stack.tsx
• apps/mobile/src/features/diffs/nativeReviewDiffSurface.ts
• apps/mobile/src/features/files/FileTreeBrowser.tsx
• apps/mobile/src/features/files/SourceFileSurface.tsx
• apps/mobile/src/features/files/ThreadFilesRouteScreen.tsx
• apps/mobile/src/features/files/thread-file-navigator-pane.tsx

💤 Files with no reviewable changes (1)

• apps/mobile/src/features/files/thread-file-navigator-pane.tsx

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[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	4.9 KiB	−23 B (−0.5%)	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	1.2 KiB	−23 B (−1.9%)	2.0 KiB	✅
Codex	Live turn WebSocket decoded	20.9 KiB	20.8 KiB	−41 B (−0.2%)	29.3 KiB	✅
Codex	Live turn messages	2	1	−1 (−50.0%)	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	1.2 KiB	1.2 KiB	0 B (0.0%)	2.0 KiB	✅
Claude	Live turn WebSocket decoded	21.2 KiB	21.2 KiB	0 B (0.0%)	29.3 KiB	✅
Claude	Live turn messages	2	2	0 (0.0%)	8	✅

Baseline: 0bfd9dd · PR result: ff02e76 · 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.

[github-actions]

🚀 Expo continuous deployment is ready!

• Project → t3-code
• Platforms → android, ios
• Scheme → t3code-preview

	🤖 Android	🍎 iOS
Fingerprint	cc64b89b3964de7f7d53a74c3fb993282ba49370	4926076389f4374b31cb0c7548960266cfb6ba3f
Build Details	Build Permalink Details Distribution: INTERNAL Build profile: preview:dev Runtime version: cc64b89b3964de7f7d53a74c3fb993282ba49370 App version: 2.0.0 Git commit: ffd8a3c947cc777817cb1ab936c5e1fa99de1472	Build Permalink Details Distribution: INTERNAL Build profile: preview:dev Runtime version: 4926076389f4374b31cb0c7548960266cfb6ba3f App version: 2.0.0 Git commit: ffd8a3c947cc777817cb1ab936c5e1fa99de1472
Update Details	Update Permalink Details Branch: pr-17073 Runtime version: cc64b89b3964de7f7d53a74c3fb993282ba49370 Git commit: ffd8a3c947cc777817cb1ab936c5e1fa99de1472	Update Permalink Details Branch: pr-17073 Runtime version: 4926076389f4374b31cb0c7548960266cfb6ba3f Git commit: ffd8a3c947cc777817cb1ab936c5e1fa99de1472
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