I've used a very similar workflow somewhat by accident for some larger changes. I'll be chatting with Codex about the best way to implement and watch my context slowly dwindle down, so I ask it to write out the plan to some dir (e.g. tasks/some-feature/). I recently had it write out a 10 step plan, as in 10 large, detailed files. I just ask it to implement the first file in a fresh context, check it over, get it to fix anything up, then start the 2nd file in a fresh context. It was smart enough to document 'deliverables' and verification for each step. Worked relatively well.
Might not be a bad idea to formalize this process with a skill.