debuglisted

# Debug When this skill is activated, find the *root cause* of a bug through disciplined investigation — not by guessing and patching symptoms. The output is a cause backed by evidence and a minimal, targeted fix. ## Clarifying Questions Before investigating, ask the engineer the following. Skip any already clearly answered in the conversation. **Wait for the answers before proceeding.** 1. What is the observed behavior, and what is the expected behavior? Be specific. 2. What are the exact reproduction steps? Does it fail every time, or intermittently? 3. What is the environment (OS, runtime version, branch/commit, relevant config)? Does it reproduce locally? 4. When did it last work? Was there a recent change, deploy, or dependency bump? 5. What error messages, stack traces, or logs are available? ## Steps 1. **Reproduce first.** Confirm the failure locally before changing anything. A bug that cannot be reproduced cannot be confirmed fixed. If it cannot be reproduced, say so and gather more signal instead of guessing. 2. **Narrow the surface.** Use the stack trace, logs, `git log`/`git bisect`, and the diff since the last known-good state to localize the suspect area. 3. **Form hypotheses.** Write down the candidate causes, ordered by likelihood given the evidence. 4. **Test one hypothesis at a time.** Make the smallest possible probe (a log line, a breakpoint, a targeted check). Change one variable per experiment. Record what each result rules in or out. 5. **Confirm