Systematic 4-phase debugging — root cause investigation, hypothesis testing, regression-guarded fix, mandatory bug doc. Auto-invoke when a bug is non-trivial or a previous fix didn't stick — signals: bug recurs ("still broken", "same error again", "came back"), flaky / intermittent / race / timing,
Systematic 4-phase debugging — root cause investigation, hypothesis testing, regression-guarded fix, mandatory bug doc. Auto-invoke when a bug is non-trivial or a previous fix didn't stick — signals: bug recurs ("still broken", "same error again", "came back"), flaky / intermittent / race / timing, "used to work, now broken", regression after update or dependency bump, hard-to-reproduce, works loc