Commit Graph
2 Commits
Author SHA1 Message Date
Mohamed Boudra 8dd4da6ee0 Keep mobile streaming and panel motion stable under JS stalls (#4190)
* fix(app): activate mobile panels after motion settles

Gesture previews were publishing React presentation state and activating retained content before the native motion finished. Keep transient motion on the UI thread and publish the active panel only from the accepted animation completion.

* perf(app): re-render only changed history rows

Every coalesced stream tick re-rendered all mounted history rows because the inverted FlatList recreates each cell with a new index and ref. Keep layout item identity for unchanged rows and memoize the row on it, and resolve tool-call groups through a stable event so the render callbacks stop churning.

* perf(app): count replica row bytes once

Budget accounting measured every stored row of a touched host on each persist through the Buffer polyfill. Cache the UTF-8 length per immutable row and count without materialising bytes.

* fix(app): settle mobile panels on position

Activity now follows the UI-thread position reaching the canonical anchor instead of an animation completion callback. A successful gesture keeps its finishing motion and the matching command adopts it; settlement and command acceptance may arrive in either order.

* fix(app): keep settled panel props across JS stalls

Turn off Reanimated's FORCE_REACT_RENDER_FOR_SETTLED_ANIMATIONS. Its settled-props collector drops entries older than two seconds before React receives them, so a JS stall across a settle left the overlay display and backdrop opacity reverted on the next commit while the store held the new panel.

* fix(app): reconcile hidden keyboard end on iOS

Only a hidden end event resets the keyboard shift. A late visible end no longer resurrects a keyboard that already dismissed.

* fix(app): focus the replacement input through autoFocus after clearing

Clearing swaps the native input for a fresh instance. Focusing the doomed instance asked Android for the keyboard and then tore the focused view down, which cancelled the show; a JS focus command sent alongside the remount reached a view that was not attached yet and the IME ignored it. Focus and blur requested while the replacement is pending now decide the replacement's autoFocus, which native applies once the view is attached.

* fix(app): revise history rows in every viewport

The history row memo boundary bails out until its item identity changes, but only the native viewport cloned rows flagged by historyRowRevision. On web and desktop a history host whose tool-call group kept updating from the live head rendered stale. Move the revision into useRevisedHistoryRows and run both viewports' history through it. Regression test renders the web strategy with a memoized row and asserts only the revised host re-renders.
2026-09-02 00:52:44 +02:00
e22ad117fd Stream assistant text at a steady rate instead of in arrival lumps (#3612)
* Stream assistant text at a steady rate instead of in arrival lumps

Assistant text arrived in lumps and was painted that way. The daemon
coalesces one message per 60ms window, and that window carries however
many characters the model produced in it, which swings by an order of
magnitude within a turn. Painting each delta as it landed made the size
of those lumps visible.

Three changes:

- The agent stream coalescer is now leading + trailing. The first delta
  after an idle window flushes synchronously instead of waiting a full
  window, matching the invariant TerminalOutputCoalescer already
  documents. The window stays at 60ms; shrinking it would raise message
  rate on a loop that already contends with terminal frames and relay
  encryption, without making the stream smoother.

- The client reducer queue commits on a frame instead of an arbitrary
  48ms timer, with the timer kept as a ceiling so a hidden tab still
  advances.

- Assistant and reasoning text are revealed at a rate derived from the
  backlog rather than from arrival timing. Arrival changes the target,
  not the rate. The store keeps the full text and only the rendered
  slice is paced, so copy, selection, the chat outline, and scroll
  geometry all stay consistent with what is on screen.

The leading flush means a burst's first chunk lands as its own timeline
row. The projection already merges contiguous same-turn rows and clients
read the projected timeline, so history is unchanged; the server tests
that assert on raw rows were updated for the extra row.

Measured on Expo web against a local dev daemon. Mock bursty-stream
provider, 6s samples, paint-on-arrival vs paced: frames that advanced
the text 55 -> 244, chars-per-frame CV 2.66 -> 1.44, gap p50 100ms ->
17ms. Real Claude Haiku agent over 52s: 84% of frames advance the text,
CV 1.29, gap p50 and p95 both 17ms (one frame at 60Hz).

Adds a bursty-stream mock model with seeded burst sizes, a gated browser
perf spec, and docs/agent-stream-performance.md.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* Address review: safe reveal boundaries and a testable seam

Two findings from the PR review.

Unicode boundaries. Slicing the revealed text at an arbitrary index could
strand a lone surrogate, which paints as a replacement glyph, or split an
emoji ZWJ sequence so a family briefly rendered as its members. Both were
visible for a frame or two mid-stream — the exact flicker the paced reveal
exists to remove. The rendered cut is now pulled back off surrogate pairs,
combining marks, variation selectors, skin tone modifiers, and ZWJ joins.
The reveal counter stays monotonic and only the painted boundary moves, so
a long cluster cannot stall the reveal.

Test placement. The hook test used JSDOM, @testing-library renderHook, and
monkey-patched requestAnimationFrame, all of which docs/testing.md rules
out; it prescribes fixing the missing seam instead. The reveal policy is
now a pure state machine in text-reveal.ts (begin/retarget/advance/
complete/visible) covered by plain unit tests with no environment, and the
hook is reduced to the frame-clock binding. Rendered behavior is left to
the browser spec, which no longer carries frame sampling and statistics in
its body — those moved to e2e/support/helpers/stream-smoothness.ts.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* Measure total painted text, not the tail message

The smoothness sampler read the length of the last assistant-message
element. A real turn emits many assistant messages, so that element keeps
changing identity and its length is not monotonic — handovers read as
resets, and a stream that was plainly moving on screen reported almost no
growth at all. Sampling the total across every assistant message fixes it.

This invalidated the numbers previously recorded for the real-agent run,
so the doc table is replaced with a fresh A/B taken with the corrected
sampler against a Claude Haiku agent: frames that advanced the text 6% ->
87%, chars-per-frame CV 4.11 -> 1.86, gap p50 317ms -> 17ms, p95 383ms ->
17ms. The paced column also reported zero Unicode defects across a stream
containing emoji, which exercises the reveal boundary clamp end to end.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* perf(agent-stream): harden paced text reveal

Use standards-compliant grapheme segmentation when available and preserve full arrivals on older runtimes. Cap reveal commits at 60Hz and measure the real browser rendering path so high-refresh displays stay smooth without rendering at hardware frame rate.

* Hold back trailing fragments split by arrival boundaries

The reveal boundary is not the only place a grapheme gets cut. The
daemon's coalescing window ends a delta wherever the window closes, so a
caught-up reveal can be handed half a cluster and paint it. Measured on a
mixed-script Haiku stream: five frames in ~350 ending in a single regional
indicator, i.e. half a flag on screen for a frame.

While the turn is streaming, a trailing fragment that cannot stand alone —
a dangling high surrogate, a trailing joiner, an odd regional indicator —
now waits for the rest of its cluster. Once the turn ends everything
received is painted, because nothing more is coming. Complements the
grapheme-boundary clamp, which handles the reveal cut; this handles the
arrival cut.

The same stream now measures one such frame in ~400 rather than five. The
remainder is a flush boundary that coincides with the end of an assistant
message, putting the two halves in different messages, which the client
cannot rejoin — that one belongs in the coalescer.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
Co-authored-by: Mohamed Boudra <boudra.moha@gmail.com>
2026-08-25 23:37:46 +02:00