migration-guide-writer

Creates problem-oriented migration guides following the Diátaxis How‑To pattern. Maps old APIs to new APIs with before/after examples, documents breaking changes, and provides troubleshooting. Zero tolerance for fabricated APIs or unverified performance claims. Use when a new system replaces an old one, breaking API changes occur, major version upgrades are required, services are decomposed, deprecation notices are needed, or architectural changes must be documented.