Earlier quoted context omitted.
My experience with both Opus and GPT-codex is that they both just forget to implement big chunks of specs, unless you give them the means to self-validate their spec conformance. I’m finding myself sometimes spending more time coming up with tooling to enable this, than the actual work.
I just use beads or Github issues. Plan/spec first, split it into issues. Then reset context and implement each task one by one. Nothing gets forgotten.
In my experience you have to refer to the relevant docs on things explicitly in every single issue for it to work well.