Since the unread rooms stream was scoped per user, posting a message
publishes the room id once to each member of the room. Each publish is a
round trip to Redis, made one after another inside the request, so the time
to post a message grows with the size of the room and in a big room is far
more than the rest of the request.
The fanout now runs in Message::BroadcastUnreadRoomJob, so the poster no
longer waits for it. Who gets the notice and what it says are unchanged.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NuTtwJKhb77Dv7EQqv2C3C
UnreadRoomsChannel streamed from a hardcoded global name, and every message
published its room id to it. Any authenticated user, including one with no
memberships at all, could subscribe and watch which rooms were active and exactly
when, across every closed room and direct conversation on the account. The browser
filters ids it doesn't recognise, but that happens after delivery.
Its sibling ReadRoomsChannel is already scoped per user; this mirrors it, and
message creation fans the notice out to the room's members instead of broadcasting
it to everyone. No message content was exposed either way, only the timing.
Marcello Costagliola
Jeremy Daer
Kevin McConnell