A possible cheap win for servers would be to support the systemd "here's an fd number you get exec'ed with" model - that way server code that's only written to do read/write on a normal fd should be trivial to wire up to unix sockets, TCP sockets, etc.

(and then having a smol node/bun/go/whatever app that can sit in front of any server that handles stdio - or a listening socket for a server that can handle multiple clients - and translates the protocol over to SSE or websockets or [pick thing you want here] lets you support all such servers with a single binary to install)

Not that there aren't advantages to having such things baked into the server proper, but making 'writing a new connector that works at all' as simple as possible while still having access to multiple approaches to talk to it seems like something worthy of consideration.

[possibly I should've put this into the discussion, but I have to head out in a minute or two; anybody who's reading this and engaging over there should feel free to copy+paste anything I've said they think is relevant]