Deprecation & Migration
Starts from a code-as-liability mindset: every line has ongoing cost — tests, docs, security patches, onboarding overhead — so code that no longer earns its keep should go. Because Hyrum’s Law makes any observable behavior something a consumer depends on, removal requires active migration, not just an announcement. The skill distinguishes advisory deprecation (optional, migrate on your own timeline) from compulsory (hard deadline, but you must supply migration tooling), defaulting to advisory.
It supplies a build-the-replacement-first migration process, patterns (strangler, adapter, feature-flag switching), the Churn Rule (infrastructure owners migrate their own users), and a protocol for removing zombie code — unowned code that everyone depends on. This is really a maintenance activity folded into the release stage for now, since no other framework in the wiki covers it.
See Also
- pattern-contract-first — the discipline strained when retiring a contract consumers depend on.
- stage-release — the stage this is folded into.