The check had been green for a week. It greps every diff under src/ for import mock, because production code has no business importing a mock library. Then it went red on src/payments.py, a file with no mock import anywhere in it. The word mock was sitting in a docstring, in a sentence telling the next developer not to import one. The grep matched the sentence. The quickest way to clear that red is to delete the check.
The series opener named the loop that runs generate, check, steer, retry, stop, and put the hard part on the check that decides good enough, stop. Last week's piece built that check as no-mocks.sh and set a gate beside it, a hook that refuses a bad write instead of catching it after the fact. This one stays with the check and asks what happens when it is wrong: how to tell a broken instrument from a signal that was never there.
What a check is here
A check is a function from the agent's output to a verdict: pass or fail. In the loop it is the thing that decides whether an iteration is acceptable and whether to run another. A check comes in two kinds. A deterministic check runs the code or scans the text and returns the same verdict every time: grep, pytest, an exit status. A model-graded check asks another model is this good? and reaches criteria the first cannot express, at the cost of the same unreliability the loop was built to contain.
