What problem does it solve? Code coverage tells you which lines ran during tests, but not whether tests would fail if the code were wrong. This Skill performs static pseudo-mutation analysis — reasoning about hypothetical changes like boundary flips, boolean inversions, and removed null checks — to reveal test gaps where bugs would slip through undetected. ## Core Features & Use Cases - Mutation Point Catalog: Identifies boundary, boolean, return value, exception, arithmetic, and null-check mutation points across .NET, Python, TypeScript/JavaScript, Java, Go, Ruby, Rust, Swift, Kotlin, PowerShell, and C++. - Kill/Survive Classification: Classifies each mutation as Killed, Survived, No coverage, or Equivalent, with concrete recommended test fixes for every gap. - Risk-Prioritized Reporting: Produces a mutation score summary plus prioritized findings, so high-risk business logic gaps surface before trivial ones. - Use Case: Ask "would my tests catch it if someone flipped this comparison operator?" and get a per-line verdict showing which tests cover the code but fail to assert the affected behavior. ## Quick Start Ask the agent to analyze whether your existing tests would catch subtle bugs in a specific source file and its corresponding test file.
