How to make a state available to all beans in a “session”?

Question

I have the following design. When a client makes a request to the server, the server creates a state that holds all sorts of info. There are various stateless and stateful beans

Answer 1

I can't inject a stateful bean into a stateless bean.

You can absolutely inject dependencies this way.

If the stateful bean is @RequestScoped, any call into the stateless bean on that thread that hits a CDI injected contextual reference (iow proxy) will find its way to the right instance of the stateful bean.

As long as you use CDI, you don't need to trouble yourself with trying to stash things away in your own threadlocals.