What problem does it solve? Engineering teams are good at building systems but poor at removing them, leaving zombie code, duplicated implementations, and unmaintained legacy services that accumulate security debt and maintenance cost. This Skill provides a disciplined process for deciding what to deprecate, migrating consumers safely, and fully removing old code. ## Core Features & Use Cases - Deprecation Decision Framework: A structured checklist to evaluate whether a system still provides unique value, how many consumers depend on it, and whether a replacement exists before deprecating. - Migration Patterns: Concrete patterns including the Strangler Pattern, Adapter Pattern, and feature-flag-based migration, with TypeScript examples for incremental consumer cutover. - Advisory vs. Mandatory Deprecation: Guidance on choosing between soft deprecation with warnings and hard-deadline deprecation with migration tooling. - Use Case: When replacing an old internal task service with a new one, use this Skill to announce the deprecation with a migration guide, migrate consumers one at a time behind a feature flag, verify zero active usage, and then delete the legacy code, tests, and docs. ## Quick Start Ask the agent to draft a deprecation and migration plan for the legacy service you want to retire, including a replacement strategy and consumer migration steps.
