deprecation-and-migration

SUMMARY

What it does

This Agent Skill provides guidance on deprecation and migration of software systems, APIs, and features. It covers when to use, core principles (code as liability, Hyrum's Law, design-time planning), the deprecation decision process, compulsory vs advisory deprecation, migration steps (build replacement, announce, migrate incrementally, remove old system), migration patterns (strangler, adapter, feature flags, expand/contract database migrations), handling zombie code, common rationalizations, red flags, and verification checklists. The skill is a markdown document (248 lines, 12516 bytes) with no executable code or tools.