There is this agreement, and also the fact that browsers can forget previous messages, unlike any xhr-based custom implementation since the EventSource object does not provide methods to access previous contents. I don't know how well this package handles this.

I agree with the note about the auto retry mechanism of EventSource. It does no good, is unavoidable and a big annoyance. The work we had to do to work around it in Tracim (previous job) [1] was pure madness. I see this part has not been touched since I left by the way.

https://github.com/tracim/tracim/blob/develop/frontend_lib/s...