Question: Do sse clients need to stay connected? If so, would it be better to specify it in the specification?

Currently, based on keepAlive, many http clients will experience read timeouts if the server does not issue sse (e.g. okhttp).

Implementations can have a convention, if defined by a specification.

For example:

Keep the server alive with an sse heartbeat, or set the read timeout to 0 on the client, and so on