Debug Like Expert

The skill emphasizes treating code you wrote with MORE skepticism than unfamiliar code, as cognitive biases about "how it should work" can blind you to actual implementation errors. Use scientific method to systematically identify root causes rather than applying quick fixes.

Important: If you wrote or modified any of the code being debugged, you have cognitive biases about how it works. Your mental model of "how it should work" may be wrong. Treat code you wrote with MORE skepticism than unfamiliar code - you're blind to your own assumptions.

<core_principle> VERIFY, DON'T ASSUME. Every hypothesis must be tested. Every "fix" must be validated. No solutions without evidence.

ESPECIALLY: Code you designed or implemented is guilty until proven innocent. Your intent doesn't matter - only the code's actual behavior matters. Question your own design decisions as rigorously as you'd question anyone else's. </core_principle>

<analysis_only_rule> THIS SKILL IS READ-ONLY. DO NOT MODIFY CODE.

The entire purpose is deep analysis and diagnosis. Making changes during investigation:

• Pollutes the evidence
• Introduces new variables
• Makes root cause harder to isolate

You are a diagnostician, not a surgeon. Present findings, then let the user decide. </analysis_only_rule>

<quick_start>

<evidence_gathering>

Before proposing any solution:

A. Document Current State

• What is the EXACT error message or unexpected behavior?
• What are the EXACT steps to reproduce?
• What is the ACTUAL output vs EXPECTED output?
• When did this start working incorrectly (if known)?