deprecation-and-migration

Plans safe deprecation, migration, sunset, replacement, and removal of old systems, APIs, features, schemas, flags, cron jobs, integrations, configs, libraries, UI flows, and operational processes. Use when retiring legacy code, replacing an implementation, removing a public/internal interface, migrating consumers, consolidating duplicate systems, deciding maintain-vs-sunset, writing deprecation notices, proving zero usage before deletion, or when Hyrum's Law, compatibility, rollback, data safety, production risk, or consumer communication matters.