What problem does it solve? Removing old systems, APIs, and features is hard because consumers depend on undocumented behaviors, and teams lack a disciplined process for sunsetting code without breaking production. This Skill provides a structured decision framework and migration playbook for retiring code safely. ## Core Features & Use Cases - Deprecation Decision Framework: Evaluate whether to maintain or sunset a system by quantifying consumers, migration cost, and ongoing maintenance burden, with advisory vs compulsory deprecation guidance. - Migration Patterns: Apply the Strangler pattern, Adapter pattern, feature-flag cutovers, and expand/contract database schema migrations with dual-write and batched backfill steps. - Zombie Code & Red Flag Detection: Identify unmaintained code with active consumers and common rationalizations that delay necessary removal. - Use Case: When renaming a PostgreSQL column, follow the expand/contract workflow — add the new nullable column, dual-write, backfill in batches, switch reads, then drop the old column in a separate deploy — so old and new code stay valid at every step. ## Quick Start Ask the agent to plan the deprecation of a legacy API or service, including a migration guide and an incremental cutover strategy for all current consumers.
