I have nothing against Codex's cli or OpenCode. I just found pi is sufficient for me and it's easy to understand what's going on under the hood.

By ChatGPT I mean the subscription plan, not the web UI. I only use gpt-5.3-codex with pi.

https://github.com/badlogic/pi-mono/tree/main/packages/codin...

> how are you using it with ChatGPT for agentic coding?

OpenAI has publically blessed people using their subscriptions with different harnesses, like OpenCode and Pi.

Extensible coding agent written in typescript. It’s exactly what you (I’m projecting) want out of Claude Code if you’re okay investing time into building your harness or prompting an agent to build it.