What problem does it solve? Engineering teams accumulate dead code, zombie systems, and duplicate implementations because removing code is harder than writing it. This Skill provides a disciplined process for deciding what to deprecate, migrating consumers safely, and fully removing old systems without breaking dependents. ## Core Features & Use Cases - Deprecation Decision Framework: A five-question checklist to determine whether a system should be maintained, migrated, or removed, including quantifying consumer count and maintenance cost. - Migration Patterns: Concrete implementations of the Strangler Pattern, Adapter Pattern, and feature-flag-based migration with TypeScript examples for incremental cutover. - Zombie Code Detection: Criteria for identifying unmaintained code with active consumers, plus guidance on assigning ownership or planning removal. - Use Case: When replacing a legacy task service, use this Skill to announce the deprecation with a migration guide, migrate consumers one at a time behind a feature flag, verify zero remaining usage via logs, and then delete the old code, tests, and documentation. ## Quick Start Ask the AI to plan the deprecation of a legacy service and produce a migration guide with an incremental cutover strategy for all current consumers.
