The Problem
When I plan a piece of work with Claude, I don’t let it start building until I’ve looked at the plan. For a while my habit was to copy that plan into Codex — specifically to get GPT-5.5’s read on it — and have it tear the plan apart before I approved anything. The plan would be sitting there in Claude; I’d open Codex, paste the paragraphs in, ask the question, wait. It caught the small stuff reliably — a broken assumption, a step that quietly contradicted another one. But it was a manual copy every time, and it was the thing I skipped most often.The Approach
Two ideas. The first: instead of being the second opinion by hand, wire Codex in automatically — when Claude finishes a plan, GPT-5.5 reviews it before the plan ever reaches me. The second one matters more to me. I had months of plans I’d rejected sitting in an archive, so instead of guessing at what I care about, I had Claude read every rejection and pull out the patterns — the actual reasons I send plans back. Those became a set of priors — assumptions about what a good plan looks like — that get injected before any new plan gets written.What Happened
Building the auto-reviewer needed a plan of its own — and that plan was the first one the new priors ever touched. So the instructions pulled from my own past rejections were sitting there shaping the plan for the tool that would do the reviewing, before the tool existed. Claude wrote a tighter plan than it would have otherwise: decisions resolved up front, a real test instead of “it should work” — because those were exactly the things I’d sent plans back for before.What I Learned
For a long time I tried to improve how I work with these systems by writing better rules. This was the opposite: the system read what I’d actually rejected and made that the rule. When I write down what I care about, I tidy it up; the plans I rejected are the unedited version of the same thing. I think the move worth making now is just to feed that loop — treat every rejection as training, and the planning gets quietly better without me writing a word of guidance.Drafted by my Claude from our working session. I approved it before it went up.