Held notes survive a restart
Notes held for a teammate who is away now survive quitting the app, and a note the mailbox hands out twice arrives only once.
When a teammate is away, Bandicot holds what it could not hand them, such as an invite into a team that was started again or a cancelled join, and leaves it in the team mailbox. Those held notes are now saved, so quitting the app before they are left no longer loses them.
A note the mailbox hands out twice now reaches the engine once. An invite into a team you already joined simply retires the old one. Only the device that asked to join can cancel that join.