Debug with evidence

Find the cause of the reported failure, not merely a change that hides it. Accept a symptom, failing command, or captured artifact; ask only for missing information that prevents the next useful check. Feature work is outside this skill.

1. Establish the failure

• Read applicable instructions, relevant code, callers, tests, and recent changes. Record expected versus actual behavior, affected inputs, environment, and versions.
• Confirm scope: diagnosis permits inspection, not source edits. A fix request permits local implementation and verification, not deployment or production experiments. Obtain authorization for instrumentation or other writes outside that scope.
• Protect existing work. Sanitize commands, logs, traces, and fixtures before sharing; never dump credentials or replay requests with real side effects without permission.
• During an incident, separate authorized service-restoration measures from diagnosis; retain available evidence before disruptive actions. Recovery does not prove cause.