Initially I was using that extension but I ran into its limitations pretty quickly. Sometimes the agent wouldn't reply over XMPP, it didn't have any support for typing indicators or status messages, and it had no way to support inter-agent communication, the agent could only ever speak to the configured owner account. I also had no way of running system commands like /new over XMPP.

The headless pi + xmpp wrapper ended up working much better because the XMPP bridge is the only interface and I get full control over its capabilities.

This is my wrapper: https://github.com/zachpmanson/pi-msg