systematic-debugging

Follow the four phases: investigate the root cause by reading errors and reproducing consistently, 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 the immediate cause to the original trigger, asking what called each level and what value was passed. Add stack trace instrumentation with console.error before the failing operation if manual tracing is not possible.

Replace arbitrary setTimeout or sleep delays with condition-based waiting that polls for the actual condition you care about, such as an event appearing or state changing. Poll every 10ms with a timeout, and only use fixed delays when testing actual timing behavior.

Stop and return to Phase 1 to re-analyze with the new information rather than stacking more fixes. If three or more fixes have failed, question the underlying architecture and discuss with your team before attempting another fix.

Never, according to this methodology. Even under production emergencies or time pressure, systematic investigation is faster than guess-and-check thrashing, and symptom fixes are treated as failures that mask the real problem.

Use the included find-polluter.sh bisection script, which runs test files one by one and checks whether the unwanted file or directory appears after each run. It stops at the first polluting test and reports the file responsible.