fix(clients): a steer splits the settled work fold

[Gigioxx]

Problem

When you steer a running turn, the settled thread shows one "Worked for …" fold under the first prompt, then the steer, then the answer. That fold hides the work done after the steer too, so it reads as if the agent did all the work before the steer and then answered it instantly.

Fixes #15279.

Fix

A steer now splits the settled fold, the same way an automatic wake already does: prompt → "Worked for 6m 11s" → steer → "Worked for 49m 8s" → answer.

• deriveTurnFolds (web) and deriveThreadFeedRunFolds (mobile) still group work by run. They also record where each steer falls in that same run and emit one fold per section that hides work. Queued prompts and other runs' entries don't split a fold.
• Each fold's duration ends at the steer after it. The first starts at the run start, and the last ends at the run end. Time with no folded work joins the next fold, so the folds still add up to the run's total and nothing relies on first-activity timestamps.
• Each fold expands on its own: a split run keys its folds ${runId}:${anchorEntryId}. A run with one fold keeps the run id as its key and row id. A bare run id (from an interrupt or a citation) still expands every fold of the run.
• The live "Working" row is unchanged. It stays under the first prompt, as fix(web): keep the active-run header with the prompt that started it on steer #11828 intended. Only settled folds split.

Scope and approval

One problem: steered turns fold their work in the wrong place. #15279 was triaged by @juliusmarminge, who confirmed the cause and suggested this direction ("split only the settled fold into sections at each steer"). Mobile has the same per-run grouping, so it gets the same change.

Verification

• Reproduced on main (c5bc98db03) with real data: I copied a read-only snapshot of my own database into the worktree's .t3 and opened a Claude thread with a steer in an isolated Playwright browser. It showed one "Worked for 55m 19s" fold above the steer. With the fix, it shows "Worked for 6m 11s" above the steer and "Worked for 49m 8s" below it (6m 11s + 49m 8s = 55m 19s). Expanding the second fold shows only the post-steer work, and the row stays in place.
• vp test run apps/web/src/components/chat/MessagesTimeline.logic.test.ts apps/mobile/src/lib/threadActivity.test.ts: 225 passed. The new web and mobile tests fail without the fix. The old "keeps the duration header at the initiating prompt" test now expects the settled fold below the steer. Its live-header assertions are unchanged.
• Web and mobile tsc --noEmit pass. Scoped lint has 0 errors (all warnings already exist on main). Format passes.
• Not checked: a native mobile device (covered only by the unit test), the desktop shell, and remote connections. The change is client-only presentation logic, with no contract or server changes.

Before:

After:

After, with the second fold expanded (only post-steer work shows):

Model: Claude Opus 5.5. Harness: Claude Code in T3 Code.

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This cross-platform change introduces substantial per-steer folding, timing, and disclosure-state behavior on existing web and mobile paths. Several unresolved medium-severity findings also identify concrete edge cases around steer boundaries, interruption expansion, queued prompts, and summary placement.

Not approved because:

• 5 blocking correctness issues 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.}

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📥 Commits

Reviewing files that changed from the base of the PR and between d2f1d15 and 90b0a2c.

📒 Files selected for processing (6)

• apps/mobile/src/features/threads/ThreadFeed.tsx
• apps/mobile/src/lib/threadActivity.test.ts
• apps/mobile/src/lib/threadActivity.ts
• apps/web/src/components/chat/MessagesTimeline.logic.test.ts
• apps/web/src/components/chat/MessagesTimeline.logic.ts
• apps/web/src/components/chat/MessagesTimeline.tsx

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📝 Walkthrough

Walkthrough

Settled run folds in web and mobile timelines now split at steer messages. Each section has its own duration, anchor, and expansion key. Users can expand a section or all sections in a run.

Changes

Steer-aware run folds

Layer / File(s)	Summary
Derive fold sections apps/web/src/components/chat/MessagesTimeline.logic.ts, apps/mobile/src/lib/threadActivity.ts, apps/web/src/components/chat/MessagesTimeline.logic.test.ts, apps/mobile/src/lib/threadActivity.test.ts	Both timeline implementations record steer boundaries and derive folds for eligible sections. Each section gets its own duration and anchor; interrupted-run wording applies only to the final section. Tests cover fold placement, durations, and independent expansion.
Track fold expansion keys apps/web/src/components/chat/MessagesTimeline.tsx, apps/web/src/components/chat/timelineScrollAnchoring.ts, apps/mobile/src/features/threads/ThreadFeed.tsx, apps/web/src/components/chat/MessagesTimeline.logic.ts, apps/mobile/src/lib/threadActivity.ts	Web and mobile disclosure state and callbacks use string expansion keys. Fold rows use those keys for their identifiers and expanded state. Remembered web disclosure state also accepts string keys.

Priority: ⬇️ Low

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

Change: Bug fix · Severity of issue fixed: Low

Suggested reviewers: juliusmarminge

Merge Risk: ⚪ Minimal · up to 90b0a

The previous fold-expansion cleanup issue is addressed, and no merge-blocking behavior was established. The change is ready for normal merge checks.

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Out of Scope Changes check	⚠️ Warning	The PR also changes server pull-request provider error handling. PullRequestProviderError adds a not-found reason, and provider mappings and tests handle that reason. These changes do not implemen…	Remove the unrelated server pull-request provider changes and their tests from this PR, or establish a directly linked issue that requires them.
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 9 functions across 7 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: a steer splits the settled work fold.
Description check	✅ Passed	The description covers the problem, change, scope and approval, and verification. It includes focused test results, limitations, and before-and-after screenshots. The "Fix" heading serves the template…
Linked Issues check	✅ Passed	Issue #15279 requires each steer to separate the settled work fold for its run. The web and mobile fold logic emits a fold for each section and preserves independent expansion. The tests cover steer b…

Full details: Out of Scope Changes check

Explanation

The PR also changes server pull-request provider error handling. PullRequestProviderError adds a not-found reason, and provider mappings and tests handle that reason. These changes do not implement or verify the fold behavior in #15279.

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Actionable comments posted: 1

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Inline comments:
Review comments at @apps/web/src/components/chat/MessagesTimeline.tsx:
- Around line 666-673: Update the run-change effect in MessagesTimeline and the
corresponding effect in ThreadFeed to remove every expanded key equal to
previous.runId or prefixed by previous.runId plus a colon. Preserve other runs’
expanded keys.

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📥 Commits

Reviewing files that changed from the base of the PR and between 237d51e and d2f1d15.

📒 Files selected for processing (7)

• apps/mobile/src/features/threads/ThreadFeed.tsx
• apps/mobile/src/lib/threadActivity.test.ts
• apps/mobile/src/lib/threadActivity.ts
• apps/web/src/components/chat/MessagesTimeline.logic.test.ts
• apps/web/src/components/chat/MessagesTimeline.logic.ts
• apps/web/src/components/chat/MessagesTimeline.tsx
• apps/web/src/components/chat/timelineScrollAnchoring.ts

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[maria-rcks]

Note

Written by gpt-6.1-sol on behalf of Maria

Thanks for investigating the misplaced work fold after a steer. The 609-line change across seven files exceeds what we can take over from an unvouched contributor under our current review-capacity policy. Right now we are only taking focused bug fixes from outside contributors. Please add your findings to #15279 and coordinate a smaller fix there for reconsideration.