How to use GitHub Action with ChatGPT plan?

What is the type of issue?

Documentation is confusing

What is the issue?

I would like to use the GitHub Action with my ChatGPT plan but it's unclear how to do this (an API key seems to be required).

Claude Code's GitHub Action supports this functionality with my Max subscription and I'd like Codex's to work with ChatGPT Pro in similar fashion.

Where did you find it?

https://github.com/openai/codex/tree/main/.github/actions/codex