debug

Debug

Systematic 7-step debugging. Don't guess — trace.

Steps

1. Reproduce — get a minimal, reliable reproduction
2. Locate — find the exact file, line, and call path where it breaks
3. Hypothesize — list 2-3 competing explanations
4. Evidence — for each hypothesis: what would confirm or rule it out
5. Test — run the fastest confirming/ruling test first
6. Fix — change exactly what the evidence points to
7. Verify — confirm fix resolves the issue, run full test suite

Rules

• Never change code before you know the root cause
• Read the actual error message — don't skim it
• Check assumptions: is the value what you think it is? Add a log
• Distinguish "symptom" from "cause" — fix the cause
• If stuck after 3 hypotheses, add instrumentation before guessing more

Output

Root cause: <one sentence>
Location:   <file>:<line>
Fix:        <what to change and why>