Pi is a LLM agent harness similar to OpenCode, claude code CLI, OpenAI Codex.

It's a minimal TUI to "talk" to an AI. Mostly for coding. And it's build in a way where it's minimal and user can extend or write plugin without restarting.

Given the client and it being open source, they get (too) many bug reports and pull requests. So much so that every bug and PR gets auto closed, unless you are known to the developers.