I'm open to feedback, particularly about the ephemeral option. Not sure that's the right name/structure, especially since there are other state related parameters (eg. sqlite-pragma) that might make sense to be exposed.

Would this be better compared to the current ephemeral option?

{
    state = {
        ephemeral = true|false;
        sqlite-pragma = {
            # ...
        };
    };
}

I added a separate section for state config matching the above.

Hm, that bind: address already in use error is weird. Any chance these tests run in parallel on those machines? Would it make sense to randomize ports?

Maybe it just needs a retry.

Does temporal run in foreground so it can be properly stopped?

It does, but the shutdown process may not be instantaneous.

I tried changing the port, maybe there is a collision.

Apparently, there is something running on that port. Changing the port fixes the problem. I also fixed the script, so hopefully it's going to work now.

Breaking jobs seem unrelated to me. I think this is ready.

seems related to NixOS/nixpkgs#233265

Can I get a review on this? Since the breaking builds are unrelated, any chance this can get merged?