Agent Skills: caching

Expert guidance for Rails caching — fragment caching, Russian doll caching, cache keys/versioning, low-level caching (Rails.cache), conditional GET (stale?/fresh_when), and cache stores (Solid Cache, Redis, Memcached). Use when implementing cache, caching, fragment cache, Russian doll, Rails.cache, Solid Cache, cache key, HTTP caching, stale?, fresh_when, cache store, or optimizing performance.