It's been interesting reading this thread and seeing that others have also switched to using Codex over Claude Code. I kept running into a huge issue with Claude Code creating mock implementations and general fakery when it was overwhelmed. I spent so much time tuning my input prompt just to keep it from making things worse that I eventually switched.

Granted, it's not an apples-to-apples comparison since Codex has the advantage of working in a fully scaffolded codebase where it only has to paint by numbers, but my overall experience has been significantly better since switching.

1) create plan in plan-mode

2) ask it to implement plan

That's the way to work with Claude.

Other systems don't have a bespoke "planning" mode and there you need to "tune your input prompt" as they just rush in to implementation by guessing what you wanted