systematic-debugging

Use this skill whenever a test fails, a code review surfaces a defect, or a bug is reported, to perform structured root-cause analysis rather than trial-and-error patches. Walks symptom → narrow → reproduce → minimal repro → root cause → fix → regression test. Outputs a debug log entry that feeds into Memory and AUDIT_BUNDLE. Chinese trigger examples: "调试", "找 bug 根因", "系统化调试", "Bug 定位", "test failure 调试", "review 反馈 修复". Do NOT use for stylistic feedback (just fix), do NOT use for known one-line fixes. Success = root cause identified with evidence, fix applied at root cause level, regression test added.