# Regression Test Checklist

This change touches existing behavior. Protect it with tests.

- Add a test that fails against the current (unfixed) code and passes after your
  change, demonstrating the finding is actually resolved.
- Cover the edge cases and failure modes implied by the finding, not only the
  happy path.
- Reuse the project's existing test harness, fixtures, and conventions; do not
  introduce a parallel testing style.
- Do not weaken or delete existing assertions to make the suite pass. If a test
  must change, justify why the old expectation was wrong.
- Avoid mocking the component under test; mock only true external boundaries.
- Keep tests deterministic: no reliance on wall-clock timing, network, or
  ordering that can flake.
- Run the full configured test command, not just the new test, and confirm no
  regressions elsewhere.
