[saphid]

Problem

Scrolling the mobile terminal accessory schedules React state updates for each accepted horizontal offset even when both edge fades stay the same. React Compiler already caches the ScrollView and its children, but the parent scroller still executes for unchanged fade output.

Change

Keep accepted scroll/layout metrics in an event-only ref and publish state only when a fade flag changes. Retain the existing 1px accepted-offset filter, strict 4px edge comparisons, content/viewport recomputation and native scroll event cadence. Keyboard, modifier buttons, accessibility, layout and scrolling props are unchanged.

Scope and approval

This is a focused redundant-update correction in the existing terminal accessory scroller, with no new setting or product behavior. Only ComposerToolbar.tsx changes. Related #24628 changes terminal toolbar placement and #22161 changes modifier input; their inspected patches do not address fade-state publication.

Verification

• A dynamic production-compiled React harness executes the actual baseline/candidate component, including React Compiler caches, using native host stand-ins. The baseline optimization assertion fails; candidate passes. For 300 interior scroll events, parent executions and setter calls fall 300→0, while ScrollView/child executions are 0→0. Across 868 events, all 863 observed outputs match per platform, including fractional thresholds, overscroll, resize/content changes, batched events and remounts. iOS and Android Expo production callers compile; execution uses React DOM/jsdom, not native Android.
• Scoped React Compiler test and CI=true vp run check:changed refs/heads/battery/upstream-main: exit 0. Fresh read-only GPT-6.1 Sol/high review independently reran the dynamic harness and scoped test, with no actionable findings on the exact one-file patch. Base: 53896ae.

Native compatibility: actual iPhone 16 Pro / iOS 27 Simulator base/candidate runs used the same existing terminal, left/interior/right toolbar scrolling, modifier toggles, arrow keys, retained keyboard and terminal reopen. No visible regression was observed. Exact reviewed JS overlay hashes were verified before/after; eight prior JS fixes and the native row-decode fix were held constant. Native Android was not run: the Device host selected an incomplete SDK despite a full SDK existing elsewhere. Counts establish reduced parent React/state work during scrolling, not fewer native redraws or physical battery/energy savings. No visible behavior change; unchanged-UI GIFs are omitted.

Implementation and fresh read-only review: GPT-6.1 Sol (high reasoning), Codex harness through T3 Code. Review used a fresh session of the same requested model.

Current-main verification (2026-10-29)

Integrated upstream dac8b11. Fresh independent Codex/GPT-6.1 Sol high review found no actionable source findings. The compiler case passes; the current-main production comparison preserves 863 outputs across 868 events per platform and reduces 300 interior parent executions/setter calls to zero. These are React DOM/native-host fixtures, not a native-client runtime run. CI=true vp run check:changed dac8b11ddc25bd5da62a367fdb6c3de777ae2986 passed after the merge commit, covering only this contribution.

The iOS screenshots and gestures above are historical and were not recaptured on this integrated head. Current native keyboard/modifier/accessibility behavior and Android runtime remain unverified. All eight required checks now pass on 372c9d9. GitHub reports CLEAN/MERGEABLE; Macroscope approved that exact head, and CodeRabbit found no actionable source issues with all four pre-merge checks passing. These results do not replace the current native verification limits above.

Implemented and independently reviewed in separate GPT-6.1 Sol/high sessions through Codex in T3 Code.

[macroscopeapp]

Approvability

Verdict: Approved at 372c9d9

Macroscope's review found this PR approvable — This reduces toolbar rerenders by updating state only when scroll-edge fade visibility changes. Its effects are confined to visual overlays, with no changes to product defaults or toolbar actions.

Notes:

• All code in this push has already been reviewed. Approvability was decided on eligibility alone.

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[coderabbitai]

Important

Review skipped

Review was skipped as selected files did not have any reviewable changes.

Run configuration

• Source mode: Auto
• Repository: pingdotgg/t3code
• Branch: main
• File: .coderabbit.config.ts
• Commit: 961026c
• Layers: Repository TS config
• Review profile: CHILL
• Plan: Advanced
• Run ID: 5deab8be-7440-44b7-813e-b9701bf8d51d

Commits

Reviewing files that changed from the base of the PR and between 372c9d9 and b17e917.

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Recent review info

Run configuration

• Source mode: Auto
• Repository: pingdotgg/t3code
• Branch: main
• File: .coderabbit.config.ts
• Commit: dac8b11
• Layers: Repository TS config
• Review profile: CHILL
• Plan: Advanced
• Run ID: 873a1d1f-e8d8-4cfc-9fc7-c977936fd36b

Commits

Reviewing files that changed from the base of the PR and between 9bf3158 and 372c9d9.

Files selected for processing: 1

• apps/mobile/src/components/ComposerToolbar.tsx

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Walkthrough

ComposerToolbarScroller stores content width, scroll offset, and viewport width in a ref. It keeps left and right fade visibility in state and recalculates visibility when layout, content size, or scroll position changes.

Changes: Composer toolbar fades

Layer / File(s)	Summary
Scroll metrics and fade recalculation apps/mobile/src/components/ComposerToolbar.tsx	The component stores scroll metrics in a ref and fade visibility in state. Layout and content-size handlers skip unchanged measurements. The scroll handler ignores offset changes smaller than 1 pixel. Fade visibility uses the existing 4-pixel epsilon.

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Refactor

Suggested reviewers: t3dotgg, juliusmarminge, maria-rcks

Merge Risk: Minimal · previous review 372c9

The toolbar now skips unchanged fade updates; no merge-blocking issue was established.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title is concise, specific, and accurately describes the primary performance change: skipping unchanged terminal toolbar fade updates.
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.
Description check		The description includes all required sections and clearly explains the problem, implementation, scope, verification results, limitations, and agent details. The scope section does not provide a direc…

Full details: Description check

Explanation

The description includes all required sections and clearly explains the problem, implementation, scope, verification results, limitations, and agent details. The scope section does not provide a direct maintainer approval comment, but it gives a focused-fix justification and relevant related PRs.

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Dismissing prior approval to re-evaluate 372c9d9