ds-verify-loop

Prove a change works by running the real check and fixing what it reports, not what you expect it to report.

Steps

Pick the check before you edit: the narrowest real command that proves the change, such as one test file, a typecheck, a build, or a run of the app with one request. Write the command down.
Run it once before the edit if you can, so you know the baseline (already failing, already passing, or broken for another reason).
Make the smallest edit that should satisfy the check.
Run the exact command. Read the full error output, including the first error, the file and line, and the stack frame in your code. Do not skim to the last line.
State the root cause in one sentence, based on the output. If you cannot, add one print or log line, or read the failing code, and rerun. Do not guess.
Fix the cause, not the symptom. Do not add a special case for the one input that the test uses.
Rerun the same command. Count this as one iteration.
When the narrow check passes, run the wider one once (the full test suite, the build, or a lint) to catch breakage elsewhere.
Paste the final passing output (the command and its last lines) in your reply or in PROGRESS.md.