What problem does it solve? Code changes often pass happy-path tests while silently breaking business rules, data integrity, retries, or concurrent behavior. This Skill provides a language-agnostic correctness framework that forces systematic reasoning about invariants, boundary validation, idempotency, and race conditions before defects reach production. ## Core Features & Use Cases - Invariant-First Reasoning: Start from what must always be true before and after code runs, then check persistence constraints, transactions, and unique keys that protect it. - Decision Rubric: A risk-driven table covering invariants, boundary input, persistence, retries, concurrency, and time-related hazards like clock skew and boundary dates. - Review Checklist & Handoff Rules: Concrete questions for partial failure, duplicate execution, and concurrent actors, plus routing to quality-testing, quality-reliability, and compliance-security skills. - Use Case: While reviewing a payment-processing change, apply the rubric to discover that a retry path is not idempotent and that uniqueness is enforced only in application code rather than by a database constraint. ## Quick Start Ask the agent to review this code change for correctness risks including invariants, edge cases, retries, and concurrency using the quality-correctness checklist.
