Bug Diagnosis Skill

The slowest way to fix a bug is to start changing code and hope. This skill runs a disciplined diagnostic loop: reproduce it reliably, isolate where it happens, hypothesize why, and test the cheapest hypothesis first — narrowing until the root cause is proven, not guessed. It produces a fix and an explanation of why the bug existed.

Required Inputs

Ask for these only if they aren't already provided:

• The symptom — what's wrong: expected vs. actual behavior, error/stack trace, when it started.
• Repro steps — how to trigger it (or "can't reliably reproduce yet").
• Context — recent changes, environment, frequency (always / intermittent / specific inputs).
• What's been tried — so we don't repeat dead ends.

Output Format

Diagnosis: [bug]