What problem does it solve? Database schema changes on production systems risk table locks, downtime, and irreversible data loss when written carelessly. This Skill generates safe, reversible migrations and reviews proposed ones for hazards like table-rewrite locks, unsafe NOT NULL changes, and missing indexes. ## Core Features & Use Cases - Safe Migration Generation: Produces Liquibase formatted SQL, Flyway, or plain SQL changesets with rollback statements, audit columns, and correct money/timestamp types. - Hazard Review: Detects destructive operations (DROP, renames, type changes), missing CONCURRENTLY on index builds, and NOT NULL additions on populated columns, then enforces a confirmation gate before any destructive change. - Verification & Rollback Plans: Outputs verification SQL assertions, rollback scripts, and a markdown note covering blast radius, lock behavior, and estimated downtime. - Use Case: When adding a foreign key to a populated orders table, the Skill generates a NOT VALID constraint followed by a separate VALIDATE CONSTRAINT step, avoiding an exclusive table lock during deployment. ## Quick Start Ask the agent to write a migration that adds a nullable column with an index to an existing PostgreSQL table, including rollback and verification SQL.
