Debug

One skill for a failure, from first contact to proven root cause. Three entry modes: the front-door loop (new symptom), the escalation loop (a fix already failed — references/systematic-debugging.md), and scoped mode (a test or build broke during implementation). A 54-rule technique library based on Zeller's "Why Programs Fail" backs all three.

Contract

Inputs:

• A reported symptom: error text, a crash, wrong output, or a performance number that moved.

Outputs: