Addresses bot review feedback on commit 224cab6.
## Performance: liveSegmentChars O(n²) → O(n)
The memo had three inner loops scanning all props.segments per unique
messageId. Added a single O(n) pre-pass building a
segmentsByMessageId Map, then replaced all three inner loops with
map lookups. Total complexity: O(n) instead of O(m×n).
File: packages/ui/src/components/message-timeline.tsx
## Performance: selectedTokenTotal O(n²) → O(n)
For each selected messageId, the memo scanned all segments to sum
chars. On "Select all" this was O(selected × segments). Now builds a
charsByMessageId map in one O(n) pass and does O(1) lookups per
selected message. Same pattern as aggregateTokensByMessageId.
File: packages/ui/src/components/message-section.tsx
## SSR guard: resize listener
window.addEventListener("resize", computeBadgeLayout) lacked a
typeof window !== "undefined" guard. Other window usage in the file
was guarded. Wrapped the addEventListener, requestAnimationFrame, and
onCleanup block in the guard.
File: packages/ui/src/components/message-timeline.tsx
## i18n: mirror selectionHint key in 5 locale files
messageSection.bulkDelete.selectionHint was only defined in
en/messaging.ts. Added the key (English string, since Ctrl/Shift/Esc
are universal keyboard labels) to es, fr, ja, ru, and zh-Hans.
Files: packages/ui/src/lib/i18n/messages/{es,fr,ja,ru,zh-Hans}/messaging.ts
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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