Comment by jascha_eng

huh? because im curious what they used? Claude Code and codex take completely different approaches. The core loop of feeding generation and having a bash tool is entirely the same. If you want to start building your own thing I'm sure there is good setups out there to start from rather than going from zero.

Ofc I can just fork gemini-cli if I want my own version but like I don't think that's what OP meant by build your own thing and customize it.