Calm the iOS shell-geometry handler and the timeline resize cascade - #2385
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vburojevic wants to merge 4 commits into
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Calm the iOS shell-geometry handler and the timeline resize cascade#2385vburojevic wants to merge 4 commits into
vburojevic wants to merge 4 commits into
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On every iOS visual-viewport tick (keyboard animation, URL-bar collapse, momentum settling) the shell hook forced a full-document layout via document.body.clientHeight and rewrote shell top/height plus the inherited --bb-shell-height, invalidating computed style for the whole app tree at animation cadence. - Skip all style writes when a pass recomputes the geometry it already applied, and make clearViewportOverride a no-op while nothing is set. - Cache the containing-block height; re-read it only on triggers that can resize the layout viewport (window resize, orientationchange, focusin) — never on visualViewport ticks, which move only the visual viewport. - Gate visualViewport scroll ticks on keyboard focus or an applied override: keyboard-less URL-bar pans need no compensation, while embedded-browser overrides (applied without a keyboard) keep tracking. The focusout fast-restore, the native-layout early-exit, the pinch-zoom guard, and rAF coalescing are preserved; programmatic focus (composer autofocus) still triggers one freshly measured pass, covered by a new test. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Every timeline size change re-entered layout up to five times: the scroll body's ResizeObserver delivery did a live scrollHeight/clientHeight refresh, the observed frame's bottom restore read again, and each of the three rAF settle-tail frames forced another layout — at streaming cadence on an unwindowed tree. - bottom-anchored-scroll-body: refresh the cached max offset from the ResizeObserver's own box sizes when the delivery carries entries (the scroll port's content box + the content wrapper's border box), falling back to the live read for entry-less deliveries (test stubs). The observed frame's restoreBottomOnce keeps its deliberate live read; the settle-tail frames now reuse the cache, and a tail frame that corrected drift arms exactly one live verification read on the next frame. - height-transition: size the wrapper from the entry's borderBoxSize (the same border-box metric as the offsetHeight used by the mount and snap paths) instead of the content rect; non-observer paths keep offsetHeight. The scroll-preservation contract suite passes unmodified. New settle-tail tests count geometry reads per tail frame and cover the entry-derived cache; a height-transition test pins the border-box sizing. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Every scroll event wrote data-scrollbar-scrolling (matched only by desktop ::-webkit-scrollbar rules) — a pure style invalidation on touch — and each throttled scroll-anchor sample re-ran querySelectorAll over the scroll subtree at 10 Hz while the browser was busy scrolling. - Skip the transient-scrollbar attribute when (pointer: coarse) matches. - Cache the scroll-anchor row NodeList in a ref; the existing ResizeObserver invalidates it, and an end-connectivity check covers windowed row swaps that keep the content size constant. - Raise the scroll-anchor capture throttle to 250ms on coarse pointers — restore-on-return needs the resting position (always carried by the trailing write), not mid-flick samples. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The previous comment credited Android's resizes-content path, but the focusin listener only exists on iOS WebKit. The real reason: the pass that sizes the shell for the arriving keyboard must start from the real containing block, and focus changes are rare enough to afford the read. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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This was referenced Aug 25, 2026
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Closing in favor of #2435, which integrates this PR on current Fix landed there for this PR:
Thanks for the work: the design held up under review; only the items above needed changing.
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This was referenced Aug 25, 2026
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SawyerHood
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Aug 25, 2026
…iew fixes (#2435) ## Human comments ## What was wrong Five of the mobile-perf2 PRs by @vburojevic (#2385, #2386, #2388, #2389, #2392) were each sound in design but carried one or two confirmed defects that an adversarial review found: the touch scrollbar thumb never showed after the per-scroll trim, the cached scroll-anchor row list went stale on windowed timelines, the deferred expander body blanked its preview and animated toward an empty region, the host-disconnect status fan-out ran ~5–7 synchronous queries for every thread on the host, a status change that raced an in-flight search was never refetched, the `max-age=300` app shell let browsers and the Electron window boot a stale shell whose hashed assets 404 for up to five minutes after an update, and the shared action-bar width was 16 px wider than the assistant column. This PR integrates the five on current `main` and fixes each finding, so the set can land together instead of one at a time. Credit: every original commit keeps @vburojevic as author, and every fix commit carries a `Co-authored-by` trailer for them. A squash merge credits them through those trailers; a merge or rebase keeps the authorship as-is. ## What changed Original work (21 commits, cherry-picked in PR order, unchanged): - #2385 Calm the iOS shell-geometry handler and the timeline resize cascade. - #2386 Let taps paint: transition-priority navigation, deferred expanders and sidebar realization. - #2392 Consolidate per-row ResizeObservers into shared read/write-phased observers. - #2388 Realtime round 2: status-change metadata everywhere, reconnect gating, coalesced fallback refetches. - #2389 Boot and delivery quick wins for the relayed mobile path. Fixes (13 commits; each names the finding it closes): - `bottom-anchored-scroll-body.tsx`: the `data-scrollbar-scrolling` write is back on every pointer, idempotent (one write per scroll burst); `.thread-scrollbar`/`.transient-scrollbar` are not pointer-gated, so skipping it on touch hid the thumb. The scroll-anchor row cache is bypassed when the top-level list holds a `[data-timeline-virtual-spacer]`; unwindowed timelines keep it. The scroll-preservation suite now exercises the entries-derived resize path and the scroll-gate test pins the keyboard-pan compensation. - `disclosure.tsx`: the region's content branch, height sync, transition classes, deadline and in-flight accounting key on the deferred expanded value, so the collapsed preview stays until the body exists and the tween starts from the real body; re-expanding inside the 200 ms close window keeps the retained body. - `session-owner-side-effects.ts` + `packages/db` (`listActiveHostThreads`): daemon close, disconnect grace and host removal build `statusChange` metadata only for active threads, fetched in batched queries; idle threads keep the pre-PR bare push. - `realtime-cache-registry.ts`: the `statusChange` search invalidation keeps `cancelRefetch: false` and schedules one trailing refetch after the in-flight search settles; the same two-line gap in the completed-turn path is fixed in its own commit. The coarse-pointer debounce test moved to its own file so the 65-test suite runs in the shared vitest worker again. - `server.ts`: the app shell is served `Cache-Control: no-cache` + weak build-id ETag again; the If-None-Match → 304 path is unchanged. `apps/connect/src/cache.ts`: the worker's revalidated-shell contract is now `no-cache` + ETag; the edge copy is stored with an internal 300 s bound, served only after the origin's 304, and the visitor always receives the origin's `no-cache`. `no-store`/`private`/set-cookie still bypass; the plain asset path still rejects `no-cache`. Known limit (unchanged from #2389): the edge document copy is rarely served in the mobile flow because browsers keep their own copy. - `document-cache.test.ts`: each test stores its own edge copy. `bundle-budget.json`: `maxBootBrotliBytes` 479,067 → 429,072 (10% above the measured boot payload); `maxBootBytes` unchanged. `vite-font-preload.test.ts`: head order pinned against a synthetic document, since the dist-gated suite is skipped in CI. - `MessageActionBar.tsx` / `ThreadTimelineRows.tsx` / `ConversationMessageContent.tsx`: the shared list width subtracts the assistant column's `px-2` inset; the class and the 16 px constant are declared together. No wire change between server and host daemon (`HOST_DAEMON_PROTOCOL_VERSION` unchanged; #2388's one-line `daemon-protocol.ts` edit adds no field). No CLI, guide, or doc surface changes. Not addressed, by decision: a deferred expander body can lag behind heavy streaming updates until React's transition expiry (a timeout fallback changes when the expensive render blocks the main thread, which is the trade-off #2386 is about); the transition-priority navigation in #2386 is a no-op because react-router already transitions (harmless, left as-is). ## How you verified Review: two independent multi-agent passes over each PR (correctness, claims audit with the PR's tests run, repo-rule/contract audit, one PR-specific lens), every finding checked by three refuters (code trace, a throwaway experiment against the real code, an impact judge); only findings that survived at least two of three were fixed. Fixes: each fix commit came with a test proven to fail before and pass after, and passed two independent verifiers (a diff reviewer and a runner that re-proved fail-before by restoring the pre-fix sources and ran the package suite) in one round. Final branch (`3388bcb45`): - `pnpm exec turbo run typecheck --filter=@bb/app --filter=@bb/server --filter=@bb/connect --filter=@bb/db --filter=@bb/desktop --filter=@bb/mobile --filter=@bb/cli --filter=@bb/sdk --continue` — exit 0. - `pnpm exec turbo run lint --filter=@bb/app --filter=@bb/server --filter=@bb/connect --continue` — 0 errors. - Full suites: `@bb/db` 409/409, `@bb/connect` 120/120 (the document-cache suite runs the real worker in workerd: cold store, 304-only repeat, new build on next navigation, visitor 304 relayed, pre-contract server proxied uncached), `@bb/server` 2,047/2,047, `@bb/app` 3,404 passed / 4 skipped / 0 failed. - `pnpm exec turbo run build --filter=@bb/app` + `node apps/app/scripts/check-bundle-budget.mjs` — OK: boot 1,547.5 KB raw / 381.1 KB brotli, 3 boot chunks. - EAP codename scan: clean for the working tree, tracked files, and the added lines and commit messages of `origin/main..HEAD`. Still to do by hand before merge: a physical iPhone and Android pass for #2385/#2392 (keyboard open/close, URL-bar collapse, rotation with many expanded rows); the CI iOS-simulator job is skipped. The `@bb/mobile`, `@bb/cli`, `@bb/sdk`, `@bb/integration-tests` suites and the packaged tarball smoke were green on an earlier nine-PR merge tree, not yet re-run on this exact branch. Supersedes #2385, #2386, #2388, #2389, #2392. > AGENT GENERATED --------- Co-authored-by: Vedran Burojevic <vedran.burojevic@gmail.com> Co-authored-by: Claude Fable 5 <noreply@anthropic.com> Co-authored-by: Sawyer Hood <kirbyhood@gmail.com>
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What was wrong
Two independent audits traced the worst mobile hangs (38.9s/30.7s/28.5s traces on
div[app-layout-content-shell]) to the same mechanism: on every iOS visual-viewport tick (keyboard animation, URL-bar collapse) the shell hook forced a full-document layout (document.body.clientHeight) inside a rAF and rewrote shelltop/heightplus the inherited--bb-shell-heighton an app-root ancestor, invalidating computed style for the entire 2,000–5,200-node tree at animation cadence. Each content-size change then re-entered a second cascade: the scroll body's ResizeObserver refreshed geometry live, the observed frame's bottom restore read again, and each of the three rAF settle-tail frames forced another layout — up to five forced layouts per size change at streaming cadence. Every scroll event also wrotedata-scrollbar-scrolling(desktop-scrollbar-only CSS) and 100ms anchor samples re-ranquerySelectorAllover the scroll subtree.What changed
useMobileVisualViewportHeight.ts: style writes skipped when a pass recomputes unchanged geometry;document.body.clientHeightcached and re-read only onwindow.resize/orientationchange/focusin(never on visualViewport ticks);visualViewport.scrollticks gated to run only when an override is applied or a keyboard-focusable element is focused. Embedded-browser overrides keep tracking pans; the focus-reveal pan compensation, native-layout early-exit, focusout fast-restore, pinch-zoom guard, and rAF coalescing are unchanged; programmatic focus still triggers one freshly measured pass (new test).bottom-anchored-scroll-body.tsx: the ResizeObserver path refreshes the cached max offset from the observer's own box sizes when entries are present; settle-tail frames reuse the cache with at most one live verification read after a corrected drift. Coarse pointers skip the scrollbar-attribute write, capture anchors at 250ms with a cached row NodeList invalidated by the ResizeObserver.height-transition.tsx: observer callbacks size the wrapper from the entry'sborderBoxSize.How you verified
setPropertyspy), containing-block read-count, scroll-tick gating, settle-tail read-count, entry-derived cache, border-box sizing, coarse-pointer trims, cached-NodeList invalidation; a programmatic-focus guard passes in both states by design.bottom-anchored-scroll-body.scroll-preservation.test.tsx(the Stop forced layout reads in the bottom-anchored scroll hot path #2280/Land the mobile-performance batch (#2277-#2281) and fix a scroll re-attach edge #2300 contract) passes with zero diff.pnpm exec turbo run typecheck --filter=@bb/appexit 0; full@bb/appsuite 433 files / 3,352 passed.