What problem does it solve? Hard bugs and performance regressions resist casual code reading; without a tight, deterministic pass/fail signal, debugging devolves into guessing. This Skill enforces a disciplined six-phase diagnosis loop so the root cause is found, fixed, and protected by a regression test. ## Core Features & Use Cases - Feedback-loop construction: Builds a tight, red-capable, deterministic, fast signal via failing tests, focused CTest/Qt tests, replayed traces, throwaway harnesses, fuzz loops, git bisect in isolated worktrees, or differential runs. - Structured hypothesis testing: Generates 3-5 ranked falsifiable hypotheses, then instruments with tagged debug logs or debugger breakpoints, changing one variable at a time. - Fix with regression protection: Writes the regression test before the fix at a seam exercising the real bug pattern, then cleans up instrumentation and records the confirmed hypothesis. - Use Case: A C++ Qt application intermittently produces wrong indicator values. Use this Skill to build a fixed-seed property loop that reproduces the failure at high rate, minimize the repro, test ranked hypotheses, and land a fix guarded by a regression test. ## Quick Start Ask the agent to diagnose the reported bug or performance regression and follow the phased feedback-loop workflow until a regression-tested fix is in place.
