debug-investigator

# Debug Investigator — systematic, not vibes-based Follow this loop every time. Jumping straight to "fix" without reproducing is how false fixes ship. ## The loop 1. **Reproduce.** Get a deterministic failure. If you can't reproduce, you can't fix. 2. **Isolate.** Bisect the problem space: narrow inputs, narrow code paths, narrow time windows. 3. **Hypothesize.** Form *one* explicit hypothesis. Write it in `memory/working/WORKSPACE.md` under "Active hypotheses". 4. **Test the hypothesis.** A single change that proves or disproves it — no shotgun fixes. 5. **Verify.** After the fix, re-run the repro. If the bug is gone, the repro is your new regression test. ## What to log - Each hypothesis that was wrong (high importance; these compound into domain knowledge). - The actual root cause and why it wasn't obvious. ## Anti-patterns - "It works now, not sure why" — keep investigating. - Adding `try/except` to silence an error without understanding it. - Changing five things at once and claiming one of them fixed it. ## Self-rewrite hook If the same class of bug appears 3+ times (timezone bugs, race conditions, off-by-one), promote a lesson to `LESSONS.md` and update this skill with a domain-specific sub-procedure.