Diagnose a regression and prove the fix

How these skills work together

Record the trigger, expected behavior and observed failure. Investigate the earliest component boundary that explains the mismatch. Express the missing behavior as a test that fails for the relevant reason, implement a focused correction, then run the final checks against the actual state that will be delivered. The sequence is suggested for complementary responsibilities; it does not establish that a particular environment or integration has been tested.

Validation and boundaries

A reviewer should see the original failure, the evidence supporting the cause, the initial regression-test failure and the final passing result. Add integration, browser, public deployment or physical-device evidence when the requested outcome crosses those boundaries.