Show who else is on a post right now via small overlapping avatars; show typing indicator on the comment composer; live-update vote_count and comment_count without a refresh. Powered by Supabase Realtime broadcast + presence channels (one channel per post id). Lightweight - no new tables required, presence state is ephemeral.

UI surfaces: post detail header (presence row), feedback list (live vote count ticking), team chat composer (typing dots). Tight scope - no edit conflict resolution, no "user X is editing" locks; just visibility primitives. Pairs nicely with team chat to make collaborative triage feel alive.