Follow the TDD London School (mock-first) approach: 1. Write the failing test first -- define expected behavior with mocked dependencies 2. Run the test -- confirm it fails for the right reason 3. Implement minimal code -- make the test pass with the simplest solution 4. Refactor -- clean up while keeping tests green 5. Repeat -- add the next behavior Before starting: Before reporting the outcome, run the final target tests and the regression suite after the last edit. Record the actual commands, exit codes, whether tests ran, and failing test names. The initial red test is expected during TD…