Fragment & page caching, feature flags
Cache rendered fragments, whole responses, and gate features.
cache_fragment caches a rendered template block; cache_page caches a whole handler response with Vary support; feature_flags gives boolean killswitches + percentage rollout, all backed by the same Cache trait.
Memory bound
InMemoryCache is size-capped with LRU eviction, so a flood of unique cache keys can't exhaust the process.