For Codex there is no need to decompile because unlike Claude Code, Codex is open source [1] and written in Rust.

There are lot of other amazing open source agent harnesses like OpenCode [2] and Pi [3].

[1] https://github.com/openai/codex

[2] https://github.com/anomalyco/opencode

[3] https://github.com/earendil-works/pi