I tried many packages for interacting with AI agents in Emacs, and eventually, as AI became better, I settled on just running them in terminals inside Emacs (ghostel, which is fantastic).

As for AI doing the coding in my Emacs, I simply use Claude Code or codex with the emacs-direct package which exposes the Emacs REPL via MCP. That allows the AI to do quick iteration passes and try things out in my running Emacs. Or start another one for testing.