fix(mobile): read display scale and width from the view's scene, not UIScreen.main

[juliusmarminge]

Stacked on #12049. iOS 27 makes iPhone apps resizable and SDK 58 stops reading UIScreen.main across Expo. Our terminal, review diff, and composer views still did, for hairline widths, Metal content scale, and the fallback chip width.

They now take the display scale from the view's trait collection and the fallback width from the window they sit in, so hairlines and chip truncation stay right when the app is not full screen or is on another display.

Validation: the full stack compiles on Xcode 27 (Debug simulator build). No behavior change on a full-screen phone.

Model: Claude Fable 5. Harness: Claude Code.

Review fix: chip labels rendered before initial measurement are rebuilt on the first non-zero composer layout; an unmeasured width no longer permanently truncates them. The initial image retains a finite width cap while awaiting measurement, so long labels cannot allocate unbounded images. Swift parsing passes.

Landing preparation: GPT-6.1 Sol in the Codex harness.

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

ℹ️ No successful main baseline artifact is available yet. This run establishes the initial measurement.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	—	13.5 KiB	—	15.1 KiB	✅
Codex	Thread snapshot wire	—	7.1 KiB	—	7.3 KiB	✅
Codex	Live turn WebSocket wire	—	6.4 KiB	—	7.8 KiB	✅
Codex	Live turn WebSocket decoded	—	56.2 KiB	—	66.4 KiB	✅
Codex	Live turn messages	—	9	—	21	✅
Claude	Total thread wire	—	13.5 KiB	—	15.1 KiB	✅
Claude	Thread snapshot wire	—	7.1 KiB	—	7.3 KiB	✅
Claude	Live turn WebSocket wire	—	6.5 KiB	—	7.8 KiB	✅
Claude	Live turn WebSocket decoded	—	57.1 KiB	—	66.4 KiB	✅
Claude	Live turn messages	—	10	—	21	✅

Baseline: unavailable · PR result: 240417a · 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: 114.7 KiB

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

[macroscopeapp]

Approvability

Verdict: Approved at 240417a

Macroscope's review found this PR approvable — This is a focused iOS scene-geometry bug fix that updates existing rendering and layout paths without adding capabilities, changing defaults, or suppressing static-analysis diagnostics. Full-screen behavior remains unchanged while resizable and external-display scenarios receive view-local sizing and scale handling.

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• apps/mobile/modules/t3-composer-editor/ios/T3ComposerEditorView.swift

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📝 Walkthrough

Walkthrough

Composer chip sizing now uses view-specific width sources and defers measurement when no positive width is available. Review row hairlines and terminal content scaling use the view’s trait collection display scale.

Changes

View-Specific Layout and Display Scale

Layer / File(s)	Summary
Composer chip measurement apps/mobile/modules/t3-composer-editor/ios/T3ComposerEditorView.swift	Chip sizing uses the text-container width, then the window or view width. If the width is not positive, layout retries measurement when the view has positive bounds width.
View-specific display scale apps/mobile/modules/t3-review-diff/ios/T3ReviewDiffView.swift, apps/mobile/modules/t3-terminal/ios/T3TerminalView.swift	Review row hairlines and terminal content scaling use traitCollection.displayScale.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~8 minutes

Change: Bug fix

Suggested reviewers: chrisdeeming

Merge Risk: ⚪ Minimal · up to 24041

No actionable merge-blocking risk remains in the reviewed changes.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 6 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ 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 main change: replacing UIScreen.main usage with view-scene display scale and width sources.
Description check	✅ Passed	The description explains the problem, affected components, implementation, validation results, and review fixes. It does not include explicit approval evidence or UI screenshots, but it is mostly comp…

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Actionable comments posted: 1

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Inline comments:
In `@apps/mobile/modules/t3-composer-editor/ios/T3ComposerEditorView.swift`:
- Line 973: Update the width calculation in setControlledDocumentJson so zero
window and view bounds are treated as unmeasured rather than valid chip widths;
defer or trigger makeAttributedDocument after the text container receives a
non-zero width, ensuring long chips are not permanently truncated.

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Reviewing files that changed from the base of the PR and between ae1f238 and 1ae47e5.

📒 Files selected for processing (3)

• apps/mobile/modules/t3-composer-editor/ios/T3ComposerEditorView.swift
• apps/mobile/modules/t3-review-diff/ios/T3ReviewDiffView.swift
• apps/mobile/modules/t3-terminal/ios/T3TerminalView.swift

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Dismissing prior approval to re-evaluate 4cc300b