hataa 56454af931
perf(frontend): cache settled copy-data derivation across streaming chunks (#5095)
* perf(frontend): cache settled copy-data derivation across streaming chunks

Every SSE values chunk re-renders MessageList, and the re-render re-derived
copy/toolbar text for every settled row: getAssistantTurnCopyData re-ran the
O(turn bytes) content extraction per settled group, and MessageListItem's
toolbar recomputed getMessageCopyData per message. Settled group arrays keep
their identity across chunks (deriveStableMessageGroups), so both derivations
now cache on that stable reference: a WeakMap keyed on the messages array for
turn copy data, and a useMemo on message identity for the toolbar copy text.

Fixes #5094

* fix(frontend): gate row copy-data memo and correct cache win claim

Address review: derive one memoized copy value only when
isHuman || (!isLoading && showCopyButton) and reuse it for both editing
and the toolbar, so settled assistant rows (whose toolbar never renders)
skip the derivation and human rows derive once, not twice; correct the
assistantTurnCopyDataCache comment — the regex/trim split is already
cached per message, the cache's win is the traversal/allocations for
string turns and the uncached O(bytes) map/join/trim for array-content
turns (benchmarked: 5.1x / 17.2x per settled history sweep).

* style(frontend): expand single-line messages array for Prettier
2026-08-30 14:28:43 +08:00
..