Short answer: gate channel deletion on an authoritative presence check, preserve the quiz session's stable identifiers outside the channel, and make reconnect recovery a normal state transition rather than an exception path.

The page fires after the host ends round 12. The dashboard says the quiz session is closed, yet three players still appear active and two reconnecting phones no longer agree on the current score. On-call does not need a generic "realtime error" alert here. The useful page names the session, the requested teardown transition, the last observed subscriber count, and the age of that observation.

Don't delete on the host's button press alone.

For a multiplayer quiz, presence accuracy is the primary decision axis because channel membership and business membership are different records. A player can be entitled to the session while temporarily disconnected; a socket can also remain visible after the player has left the game.…