What problem does it solve? Hard bugs and performance regressions resist casual code reading; without a reproducible pass/fail signal, debugging devolves into unfalsifiable guessing. This Skill enforces a disciplined 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, headless browser scripts, trace replay, fuzz loops, or bisection harnesses. - Ranked Hypothesis Testing: Generates 3-5 falsifiable hypotheses, instruments one variable at a time with tagged debug logs, and validates fixes against the original scenario. - Regression Lockdown: Converts the minimized repro into a failing regression test at a correct seam, then cleans up all instrumentation. - Use Case: A user reports an intermittent export failure in production. The Skill replays a captured network trace to build a red loop, minimizes the failing input, tests ranked hypotheses, and ships a fix with a regression test. ## Quick Start Diagnose this bug: the export endpoint intermittently returns a 500 error under load.