What problem does it solve? Hard bugs and performance regressions resist casual code reading; without a reproducible signal, debugging devolves into guessing. This Skill enforces a disciplined six-phase diagnosis loop that builds a tight, deterministic reproduction before any hypothesis is tested. ## Core Features & Use Cases - Feedback Loop Construction: Builds a red-capable, deterministic, fast reproduction command using failing tests, curl scripts, CLI fixtures, Playwright browser scripts, trace replays, fuzz loops, or git bisect harnesses. - Structured Hypothesis Testing: Generates 3-5 ranked falsifiable hypotheses, then instruments code with tagged debug logs or profilers, changing one variable at a time. - Regression Lockdown: Writes the regression test before the fix at a correct seam, then runs cleanup and a post-mortem that identifies architectural prevention. - Use Case: A user reports the export button intermittently throws in production. The Skill guides building a Playwright loop that reproduces the failure at a high rate, minimises the scenario, tests ranked hypotheses, and lands a fix with 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.
