Not sure if that's what you are asking but there's a `withCredentials` option (which IIRC is the only possible option)
I was looking at : https://stackoverflow.com/questions/61041389/managing-server...
Shared worker would actually allow for SSE in a service worker ! That's nice.
plus you now have to handle multiplexing and demultiplexing for different tabs on both server and client.
By the time that arrived and HTTP/2 had wide enough adoption, everyone's already used to building atop Websocket...
Also the EventSource in the browser is heavily gimped. GET only, No custom headers, and last I checked you can forget about configuring any CORS stuff for credential passing.