Get hls playlist
One HLS playlist, and the tick that says somebody is still listening to it
Read fetcher authorization
What the track fetcher holds by way of a Spotify login, and whether an authorization is already waiting to be finished
Start fetcher authorization
Starts the fetcher's one-time authorization and answers with the URL to open. Starting another replaces whichever was pending
Finish fetcher authorization
Finishes an authorization from the address the operator's browser ended up at