Do Debug

Language-agnostic systematic debugging. Four mandatory phases before any fix: Investigation → Pattern analysis → Hypothesis testing → Implementation. Works on any runtime, any language. Hands off to do-think (Mode: Interactive) after three failed fixes.

When to use this skill

Use when one of these is true:

• staring at a stack trace, panic, or assertion and asking "why is this failing"
• a fix you already tried did not stick — symptom persists, regressed, or moved
• the failure is intermittent ("works on my machine", "only in CI", "sometimes")
• the obvious layer was checked and the bug persists across multiple layers
• a senior engineer or another agent already diagnosed it and you are about to apply their fix
• you feel pulled toward "let me just try X" without naming a mechanism
• a reproducible runtime bug exists but the causal mechanism is unknown

Do NOT use this skill when:

• the task is design, architecture, or refactor with no reproducible runtime bug → do-think