1 Commits

Author	SHA1	Message	Date
Aari	f090f01806	perf(frontend): coalesce streaming renders to a frame budget instead of per chunk (#4425) ... * perf(frontend): coalesce streaming renders to a frame budget instead of per chunk While a run streams, the merge/group/render pipeline consumed every SSE chunk as its own React update (~60/s), re-rendering the whole thread tree per token. Enable the SDK's same-tick batching (throttle: true) and publish the render-facing messages snapshot at most once per 80 ms with a leading edge and a trailing flush, keyed through a memoized merge so identities stay stable between flushes. Lifecycle consumers (optimistic clearing, summarization capture, usage baselines) keep reading the per-chunk array. * perf(frontend): keep the transient bridge order array identity stable mergeTransientHistoryBridgeOrder cloned unconditionally, so the render-time call handed the coalesced merge memo a fresh array identity on every render while the transient history bridge was open, re-running mergeMessages between flushes. Clone lazily and return the input order when nothing is appended; the merge only ever appends, so an unchanged length means unchanged content. Consumers only read the returned order, so reusing the input is safe. * perf(frontend): drive the render coalescer from a monotonic clock The coalescing interval was measured with Date.now(). A backward wall-clock step (NTP correction, sleep/wake) turns the elapsed term negative, so the scheduled delay becomes interval + jump and the rendered snapshot stalls for the length of the jump. Read performance.now() once per effect invocation instead; the timer callback re-reads it because timers fire late and the next interval must start from the real flush. Seed the last-flush marker with -Infinity so the first update of a stream still takes the leading edge under a page-load-relative clock. * perf(frontend): reset the coalescer flush baseline when a stream ends The leading-edge flush was scoped to the hook instance rather than to each stream: a run starting within one interval of the previous one found a recent flush baseline and deferred its first frame. Drop the baseline when leaving the streaming state so every stream opens on the leading edge. * perf(frontend): disarm the trailing flush when the leading edge wins decideCoalesce checks the elapsed interval before the pending-timer flag, so an update arriving past the interval takes the leading edge while a trailing timer is still armed. Timers fire late under main-thread load -- exactly the regime this coalescer targets -- so that timer then publishes a second time and slips the flush baseline forward, breaking the at-most-one-flush-per- interval property when it matters most. Disarm the pending timer in the flush-now branch, and cover the previously untested elapsed >= interval && hasPendingTimer quadrant. * perf(frontend): stop syncing the render snapshot while idle The snapshot is only read while streaming, so keeping it current on every idle messages change costs one wasted render per history refetch or thread navigation. Dropping that publish outright is not safe either: the leading edge runs in a passive effect, but the render where isStreaming flips true paints first and returns the snapshot, so a stale one would be painted -- after a thread switch, another thread's messages, since the chat page deliberately avoids re-mounting on navigation. Make the snapshot nullable, where null means no snapshot belongs to the current stream, and return the live array while it is null. The idle branch then writes state once per stream end instead of once per idle update, and the stale-frame window does not exist rather than being short.	2026-07-26 08:19:13 +08:00