What problem does it solve? Hard bugs and performance regressions stall when developers guess at causes without a reproducible signal. This Skill enforces a disciplined diagnosis loop — build a feedback loop, reproduce, hypothesise, instrument, fix, regression-test — so root causes are found systematically instead of by trial and error. ## Core Features & Use Cases - Feedback loop construction: Ten ranked strategies for building a deterministic pass/fail signal, from failing tests and curl scripts to headless browser runs, replayed traces, fuzz loops, and git bisect harnesses. - Ranked falsifiable hypotheses: Generates 3-5 hypotheses with explicit predictions before testing, avoiding single-hypothesis anchoring. - Tagged instrumentation and cleanup: Every debug log gets a unique [DEBUG-xxxx] prefix so cleanup is a single grep, and a post-mortem checklist ensures regression tests and commit-message learnings land. - Use Case: A user reports intermittent checkout failures. The Skill builds a loop that replays the failing request 100 times to raise the reproduction rate, ranks hypotheses, instruments the boundary between cart and payment services, then locks the fix behind a regression test. ## Quick Start Ask the agent to diagnose the bug where the export button throws an error and have it build a reproduction loop first.
