Root cause: SoundController compared LiveKit participant p.userId
(which is homeUserId from the home instance) against currentUser.id
(local snowflake on the current instance). For federated users these
are different IDs, so the controller thought the user's own presence
was a stranger — playing user_join/user_leave for self.
Fix: use homeUserId || id for the self-check. This matches the
LiveKit identity format used in federated calls.
Jannis Braun
5ab1f7b89d