I haven't fully determined why, but when the Music Assistant server
restarts, it marks the _shairport-sync_ players as offline and will not
allow playing to them. The only way I have found to work around this is
to restart the players after the server restarts. As that's pretty
cumbersome and annoying, I naturally want to automate it, so I've
created this rudimentary synchronization technique using _ntfy_: each
player listens for notifications on a specific topic, and upon receiving
one, tells _shairport-sync_ to exit. With the `Restart=` property
configured on the _shairport-sync.service_ unit, _systemd_ will restart
the service, which causes Music Assistant to discover the player again.