If a Fetch in my ServiceWorker receives a 401 from the server how do I re-authenticate with the server if I have no focused or foregrounded client?
NB: I’m talking about POST requests updating the server and not just reading from cache until the network is back.
Bring the client back into focus? Scary for user with no action causing that reaction and they may not be there to login again anyway.
What does Background-Synch do if it gets a 401?
If navigator.credentials was surfaced in a ServiceWorker that would be enough!
Sessions that never expire?
What are other people doing?
Yet again I’m banned from W3C/IETF Github 
If someone could add the following to ServiceWorker issues https://github.com/w3c/ServiceWorker/issues/new that would help: - Please see Use-Case https://stackoverflow.com/questions/47320790/how-to-handle-session-expiry-in-serviceworker
If a User Session has expired a ServiceWorker currently has no mechanisms available to re-authenticate with the server as there is no heuristic mechanism available for determining credentials.
If the credentials.get() was available then re-authentication could take place transparently. If federated (say Google) then if the user had logged out then that state would be honoured.
The idea has some support from the ServiceWorker people