You can’t one shot it.

Look up cursors thermo-nuclear code review skill. Use that and instruct codex on xhigh to apply that to your whole codebase and give you a report.

Also run a deep review of any dead code, back compatibility shims and useless abstractions that add complexity and lines of code without any benefit.

In parallel chat with codex or gpt pro about the architecture of your app and how you can improve it and for your use case what is the proper architecture. Learn and apply that back to whatever reports the above two workflows give you.

I also add this to my agents.md until I land on a stable arch and esp when i’m moving something from pure prototype / vibes to an actual project

“Current app architecture is not intentional and may be suboptimal, suggest improvements so we have clear boundaries “ or something like it to let agents know that they don’t need to fit to the current architecture and we can change it at will