Every ReadReceiptAvatars row and every useMemberAvatar registered its own global
RoomStateEvent.Members listener — ~6 per receipt row — each firing on any
membership / display-name / avatar change in ANY room.
Add a module-level MemberChangeStore (mirroring the PERF-1 presence store) that
registers exactly ONE global Members listener and fans out to subscribers keyed
by roomId|userId. Two hooks: useRoomMemberChange (single) and
useRoomMembersChange (multi, one effect). useMemberAvatar and ReadReceiptAvatars
use them; behavior (re-render triggers) is byte-for-byte equivalent. Unsubscribe
is idempotent via a set-identity guard; the multi-hook key is order-independent.
Unit-tested (key-scoped fan-out, single shared listener, idempotent unsubscribe).
Reviewed by two passes (lifecycle/closure + behavioral equivalence) — clean.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Add a reactive `useMemberAvatar(room, userId, w?, h?, resize?)` hook
returning { name, avatarUrl }, standardizing the member name + avatar
trio and the RoomStateEvent.Members reactivity pattern (N6). Convert
ReadReceiptAvatars and EventReaders to render per-user avatars via a
small child component using the hook, preserving exact sizes, fallback
rendering, TDS pill/tooltip styling and behavior.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>