fix(mac): AppKit timeline P0s — revision adoption, disclosure height, scroll contract, SwiftUI seam - #444
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A selectionOrStatus/environment refresh rebuilt semantic rows from the previous timeline but stamped the presentation snapshot with the whole canonical revision read from the bridge — including timeline lanes it never applied. When one 33ms batch flush carried a metadata publish plus a timeline write, the controller's metadata fetch already saw the newer timeline revision, adopted it, and the buffered timeline mutation was then discarded as a duplicate: the appended row or streamed text never appeared until an unrelated structural rebuild. The refresh now stamps (held timeline lanes, applied metadata/environment lanes), so the buffered mutation applies normally. Also: a tool row's expandability now counts its parsed detail, not just its output — the expanded body shows both. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Scroll contract (docs/architecture/appkit-renderer.md): - ScrollAnchor repins on a user scroll that lands within 48pt of the tail (the doc's repin rule; previously only the dock action could repin, so a user who scrolled back down never re-followed the stream). - Scroller-knob drags and assistive scrolls are classified as user scrolling (unattributed clip scrolls in TimelineTrackingScrollView), so they finally unpin instead of being yanked back on the next delta. - scrollToBottom/jumpToTurn account for the bottom content inset; pinned streams no longer sit 10pt short of the actual tail. - The Fenwick height index rebuilds from the same measured-height source the table delegate uses, so anchor restores and turn-rail jumps stop landing off by the accumulated measured-vs-estimated delta. - The live streaming Markdown row is re-measured after every in-place update instead of keeping a byte-count estimate for the whole stream. Disclosure (P0): toggling any tool/reasoning/group/subagent disclosure now invalidates the row's cached height through a controller-installed store callback, re-queries the row height under anchor capture, and re-measures the expanded cell; the height-cache key also carries the disclosure bit so a cached collapsed height can never answer for the expanded state. Previously expanded output was clipped to the collapsed frame forever. Chevrons render only when a row has expandable content. SwiftUI seam: - ChatTimelineHost gains a Coordinator that defers pin/activity callbacks past the current SwiftUI update (mirrors SidebarListHost), removing modify-during-update hazards that dropped writes. - ChatScreen no longer stomps controller-owned pin state and activity on thread switch: returning to a thread keeps its restored viewport and the activity dock stays visible mid-run. - The pinned activity dock's measured height is reserved as bottom content inset so it stops occluding the transcript tail; the material slab behind the composer fades with a keyed animation instead of popping. - updateExternalPinState re-attaches only on a genuine transition, ending a programmatic scroll per body evaluation while pinned. Rows/chrome: the turn rail forwards wheel events to the transcript and hit-tests only its notch buttons (it swallowed scrolling over a 22pt strip); subagent command elapsed labels respect the settled-thread guard so idle threads own no ticking clock; row action failures are routed to the app's error surface instead of a DEBUG-only field. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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15 tasks
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Summary
The AppKit timeline batch from the 2026-08-02 bug hunt — both P0s plus the scroll-contract and seam defects.
P0 — chat stops updating: a metadata-only presentation refresh (status flip, context-window tick, plan progress) stamped the store with the whole canonical revision including timeline lanes it never applied; the timeline mutation buffered behind it in the same 33 ms flush was then discarded as a duplicate — appended rows/streamed text silently never appeared until an unrelated rebuild. The refresh now claims only the lanes it applied (regression test included).
P0 — clipped disclosures: expanding any tool/reasoning/group/subagent row never invalidated the cached row height, so 40 lines of output rendered inside a 44 pt collapsed frame, permanently (the cache key ignored disclosure, so scrolling away and back replayed the stale height). Toggles now route through a controller-installed store callback that drops the cache entry, re-measures under anchor capture; the cache key carries the disclosure bit. Chevrons render only for rows that actually have expandable content.
Scroll contract (per
docs/architecture/appkit-renderer.md):SwiftUI seam:
ChatTimelineHostgains a Coordinator deferring pin/activity callbacks past the current update (mirrorsSidebarListHost) — removes modify-during-update undefined behavior.Also: subagent command elapsed labels respect the settled-thread guard (no immortal 1 Hz clock on idle threads); row action failures (approve/deny/retry/stop) surface in the app's error UI instead of a DEBUG-only field.
Area
apps/mac— native macOS appapps/windowsapps/mobileapps/serverRelease size
size:XSsize:Ssize:Msize:Lsize:XLVerification
pnpm run verify --allafter merging current main: 5/5 steps pass, exit 0🤖 Generated with Claude Code