cb9a0b9250
- contract: SendOpts.mentions (opaque userId notify-list) + optional listMembers(threadId) for autocomplete/highlight (capability-degrading) - mock: listMembers; KernelClientAdapter.send forwards mentions to the socket (which already carries them → inbox MENTION items) - composer: type @ → member/@channel/@here autocomplete; Enter picks the first; on send, mentions resolve to ids; message bodies highlight @mentions - useMembers hook; mentions.tsx helpers (trailingMentionQuery/insertMention/ resolveMentions/highlightMentions) - 4 mention tests (helpers + render autocomplete→send carries id); 56 total green Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>