debug

Systematic 4-phase debugging protocol — REPRODUCE → ISOLATE → HYPOTHESIZE → VERIFY before any fix is written. Forces root-cause analysis instead of symptom patching. Writes findings to .claude/debug-notes-<slug>.md. Use when: user says /debug, 'debug this', 'why is X failing', 'fix this bug', or when a symptom is reported. Mandatory for bugs under any root named by the safety-critical.roots, auth.roots or migration.root slots of .claude/project-profile.md. Produces a HANDOFF suitable for dotnet-backend-architect or angular-senior-dev to implement the fix.