It's not just Zed, Emacs has has a thriving ACP implementation in agent-shell[0], and allows for some very cool integrations[1]. There are a fair number of other clients[2] as well.

[0]: https://github.com/xenodium/agent-shell

[1]: https://www.youtube.com/watch?v=HJQ86HuSIJI

[2]: https://agentclientprotocol.com/get-started/clients