Haven't tried tried swarm. I just run a single instance or two in different windows and it's basically what you describe: a partner you can have a conversation with.

It's an idiot savant, though. You can ask for advice but ultimate understanding and direction must come from you. The biggest gains are in the really time consuming aspects of development like searching the codebase for the root cause of a bug, writing a complex algorithm, writing unit tests. It's also great for general advice in an unfamiliar area like best practices for the db interface layer, api design, etc.

I haven't tried other languages but it really shines in rust where the compiler is your other best friend.