OpenClaw (formerly ClawdBot) is built on https://github.com/badlogic/pi-mono
It's a really nice, simple, very hackable coding agent. I've been trying it out today and really enjoy it.
This is a nice article from the creator about Pi if you want to learn more. His blog is great in general. https://mariozechner.at/posts/2025-11-30-pi-coding-agent/