Nice! 
I particularly like the way you can check single commands against the policy.
For me it’s always one of two cases:
- Let it rip (for off the cuff fun vibe sessions)
- Let me review every write/edit. (for more serious work)
Have you considered a PR to the main repo? I guess the hook system negates the need and provides a good plugin surface.
Btw, I built a traffic light system for my cli terminal assistant which helps to surface risk levels:
You’ve got me thinking that I could perhaps add a policy system too (but the use case is slightly different) 
Out of interest did you use codex cli to build this?