What problem does it solve? When a refactoring causes previously passing tests to fail, developers often guess at root causes or apply shotgun fixes. This Skill enforces a disciplined debugging methodology that locates the exact regression commit, compares old and new code semantics line by line, and cross-references all writers of shared state before any fix is attempted. ## Core Features & Use Cases - Regression Commit Localization: Uses git bisect and git diff to narrow a failure down to a single commit and read every changed file. - Semantic Change Analysis: Builds a comparison table of old vs. new read/write semantics for every modified method or accessor, exposing state migration risks. - Shared-State Cross-Referencing: Greps for all readers and writers of migrated state and draws modification timelines to reveal value drift, duplicate writes, and alias pollution. - Use Case: After moving a per-thread PC field into shared warp state, tests fail only in multi-threaded runs. Use this Skill to bisect the commit, trace every set_thread_pc call, and produce a minimal 1-3 line fix verified against the full test suite. ## Quick Start Ask the AI to use the regression-bisect skill to find which commit broke the tests after the recent refactor and identify the root cause before fixing it.
