[chrisshroba]

Processes by default get stdin and stdout. If you run a command interactively from your tty, the tty shows your stdout and collects stdin from you to pass to the process. But nothing about Unix prevents you from hooking something else up to stdin and stdout. As another commenter said, you could use sockets and have a completely generic input and output stream which an arbitrary tool could read and write to. Or you could spin up a websocket server that spawns the process and converts between websocket messages and stdin/stdout bytes. Or http requests and long polled responses. Or read input from a speech to text stream and push output into a text to speech stream.

I feel like OP’s main gripe is that persistent interactive sessions should be supported without a third party tool like tmux or screen or zellij, but one of the main strengths of Unix is that it provides platform building blocks which can be composed to create whatever experience you’re looking for.