systematic-debugging

Follow the four phases: investigate the root cause by reading errors and reproducing the issue, analyze patterns against working examples, form and test a single hypothesis, then implement one fix with a failing test case. Never propose fixes before completing the investigation phase.

Trace backward through the call chain from where the error appears to where the bad value originated. Add stack trace instrumentation with console.error before the failing operation, then fix at the source rather than at the symptom point.

Replace arbitrary setTimeout or sleep delays with condition-based waiting that polls for the actual condition you need, such as an event appearing or state changing. The skill includes a waitFor polling pattern and helper implementations with 10ms intervals and explicit timeouts.

The skill mandates root cause investigation even under time pressure, arguing that systematic debugging is faster than guess-and-check thrashing. Quick symptom fixes set bad patterns, mask underlying issues, and typically create new bugs requiring rework.

Stop after three failed fixes and question the architecture rather than attempting a fourth fix. Repeated failures where each fix reveals new problems elsewhere indicate a fundamentally wrong pattern, which should be discussed before continuing.

Add validation at every layer data passes through after finding the root cause: entry point checks, business logic validation, environment guards, and debug instrumentation. Single-point validation can be bypassed by different code paths, mocks, or refactoring.