I built training wheels for AI coding agents, then found a critical bug in them by pointing my code reviewer at them

I build coding tools with one rule: the tool has to survive its own methodology.

SeamStress is a code reviewer scoped to seams. The places where money, authorization, and tenant isolation cross. Last week I built a second thing next to it: SeamStress Scaffold, a set of five behavior protocols that install into a coding agent and make it careful exactly where seam bugs live. Read the neighbors before editing money code. Stop before anything irreversible. Quote the code instead of claiming what it does. Never edit a red test to green without saying the promise changed out loud.

The protocols are training wheels. The premise is that AI assisted development manufactures the exact condition seam bugs need: many fast sessions, each one locally correct, none holding the whole. So the agent gets questions at the boundaries and silence everywhere else.

Then I did the thing the rule requires. I pointed the code reviewer at the training wheels.

The seam I did not see