Systematic Debugging

Evidence-based investigation -> root cause -> verified fix.

<when_to_use>

• Bugs, errors, exceptions, crashes
• Unexpected behavior or wrong results
• Failing tests (unit, integration, e2e)
• Intermittent or timing-dependent failures
• Performance issues (slow, memory leaks, high CPU)
• Integration failures (API, database, external services)

NOT for: obvious fixes, feature requests, architecture planning

</when_to_use>

<iron_law>