The room you land in after Join. Host-moderated — messages post live, the host can remove, mute, kick or ban. Private users appear under a per-event alias to non-friends.
Notes. Chat is not pre-approved — messages post live and the host
moderates after the fact. Visibility is watermarked by joined_at: you see the room from
the moment you joined, not its whole history. The alias tag is shown
honestly, so nobody mistakes a masked stranger for a real name. Realtime channel authorization is
configured and tested separately from table RLS — the two are different gates.