fix(mobile): expanded tool-call groups keep following new calls

[nekohasekai]

Expanded tool-call groups on mobile stop following appended calls when LegendList reports a new height before the parent layout effect refreshes its callback ref. The follow decision consequently sees previous rows.

The merged change uses an Effect Event for the content-size callback and subscribes in a layout effect. It keeps current main's callback simplification. Credit to @nekohasekai for the diagnosis, original fix, and reproduction in #15747.

Fixes #15704.

Validation of the merged callback fix: the existing 27 follow tests pass, mobile TypeScript passes, scoped lint has zero errors and three existing warnings, and formatting passes. A reviewer also ran the mobile React Compiler coverage and follow suites: 904 tests passed across two files. One independent parallel Opus/Sol review round found no code blockers.

This PR was merged externally while the requested native verification was in progress. Subsequent EAS Android verification with production JS found another native-content race: the merged version can dispatch scroll-to-end before native content grows, leaving Call 10 hidden. That bug is addressed on the separately reviewed maintainer follow-up branch, with fix bf94273fba. That follow-up is not included in this merged PR. Its evidence and remaining publication state are recorded below.

Native verification of the shipping component and follow-up used the real internal list with synthetic fixed-height rows, production JS, and compatible EAS dev clients. Android reproduced the additional bug; iOS baseline already followed and the follow-up passed the same comparison. Follow-up streaming, scroll-away, detail-growth, resume, and rapid append controls passed on both platforms. The follow-up has 31 passing tests (27 → 31 in the existing file), passing mobile TypeScript, and three additional parallel review rounds; earlier pending-intent races were fixed and the final round found no confirmed code blockers. Follow-up PR publication awaits maintainer scope approval because this original PR is already merged.

Android before: merged version leaves Call 10 hidden	Android after: separately pushed follow-up shows Call 10

iOS before: merged version	iOS after: separately pushed follow-up

Android controls recording · iOS controls recording.

These are component-level native checks, with synthetic rows and no enclosing app navigation, real tool details, backend/provider, font-scaling, physical device, remote/relay, or native Release verification. An instrumented Android follow-up run also qualified the pending native-arrival race; its intermediate-before comparator was inconclusive and is not claimed as a native reproduction. Temporary fixtures/probes are not committed, both simulator sessions are stopped, and the Metro tunnel is stopped.

Implemented with Codex GPT-6.1-Sol; test assessment with Codex GPT-6-Astra; independent reviews by Claude Opus 5.5 and Codex GPT-6-Sol. Harness: Codex in T3 Code.

[macroscopeapp]

Approvability

Verdict: Approved at 804c543

Macroscope's review found this PR approvable — This is a small, isolated mobile bug fix that updates callback timing for existing work-log scrolling and append-follow behavior. It introduces no new capability, product default, schema, infrastructure, security, or static-analysis configuration change.

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 020b03d and 804c543.

📒 Files selected for processing: 1

• apps/mobile/src/features/threads/thread-work-log.tsx

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📝 Walkthrough

ThreadWorkGroupList now handles content-size updates with useEffectEvent. A layout effect subscribes to LegendList’s totalSize, processes the current content length, and assigns listRef directly to the list.

Changes: Thread work group content-size handling

Layer / File(s)	Summary
Content-size handling and subscription apps/mobile/src/features/threads/thread-work-log.tsx	The content-size handler uses useEffectEvent. A layout effect subscribes to totalSize, processes the current content length, and unsubscribes on cleanup. The list receives listRef directly.

Priority: ⬇️ Low

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

Change: Bug fix · Severity of issue fixed: Low

Suggested reviewers: juliusmarminge

Merge Risk: 🟡 Moderate · up to 804c5

The source-level subscription appears lifecycle-safe, but the current head has not yet demonstrated that expanded groups follow new calls on iOS or Android. Complete the stated native readiness pass before merging.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title clearly and concisely describes the main mobile fix: expanded tool-call groups continue following new calls.
Description check		The description covers the problem, change, linked issue, scope, validation results, limitations, and implementation attribution. It also clearly states that current-head native verification remains o…
Linked Issues check		[#15704] requires an expanded mobile tool-call group at its end to keep new calls visible. ThreadWorkGroupList now uses useEffectEvent for the totalSize callback and subscribes in `useLayoutEffe…
Out of Scope Changes check		The whole-PR diff changes only apps/mobile/src/features/threads/thread-work-log.tsx. The changes replace stale callback-ref synchronization with an effect event and a layout-effect subscription. The…

Full details: Description check

Explanation

The description covers the problem, change, linked issue, scope, validation results, limitations, and implementation attribution. It also clearly states that current-head native verification remains outstanding.

Full details: Linked Issues check

Explanation

[#15704] requires an expanded mobile tool-call group at its end to keep new calls visible. ThreadWorkGroupList now uses useEffectEvent for the totalSize callback and subscribes in useLayoutEffect, so the callback reads current committed rows when LegendList reports a size change. The existing append and follow rules remain in place. The reported follow suite passes 27 tests. Native re-recording is pending, but that is validation evidence and not a separate coding requirement in the issue.

Full details: Out of Scope Changes check

Explanation

The whole-PR diff changes only apps/mobile/src/features/threads/thread-work-log.tsx. The changes replace stale callback-ref synchronization with an effect event and a layout-effect subscription. These changes directly address [#15704]. No unrelated changes appear in the reviewed diff.

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Dismissing prior approval to re-evaluate 020b03d

[juliusmarminge]

Taking over this one for batch mobile-02. I’ll update it against current main, keep the useful coverage, and run independent reviews before publishing. The contributor’s commits will be preserved; no merge is planned.

Dismissing prior approval to re-evaluate 804c543