What problem does it solve? When migrating a legacy system to a new architecture or paradigm, teams struggle to prove the new system behaves equivalently to the old one. This Skill defines the validation strategy and produces parity specifications adapted to the chosen paradigm transition, so cutover decisions rest on explicit criteria rather than guesswork. ## Core Features & Use Cases - Parity strategy definition: Produces parity_specs.md selecting validation modes such as shadow mode, characterization tests, contract tests, and data parity, with measurable acceptance criteria and cutover blocking rules. - Paradigm-adapted coverage: Adjusts required test dimensions based on the paradigm transition (e.g., synchronous to event-driven requires idempotency, ordering, and queue-failure scenarios; OO to functional requires immutability and composition checks). - Gherkin spec generation: Writes one .feature file per critical flow with traceability to process flows, target architecture, and business rules, including screen parity scenarios (golden file comparison or component contract tests) when the legacy system has a UI. - Use Case: After a migration team decides to move a monolithic synchronous system to an event-driven architecture, invoke this Skill to generate parity specs requiring idempotency and message-ordering scenarios for every critical flow, plus a divergence metric that blocks cutover if exceeded. ## Quick Start Run /reversa-inspector after the migration strategy and target architecture are approved to generate parity_specs.md and Gherkin parity test files under _reversa_sdd/migration/.
