Next.js 16

Next.js 16 introduces Cache Components with opt-in caching using the "use cache" directive, completing Partial Pre-Rendering (PPR) for granular static/dynamic rendering control. Turbopack becomes the default bundler with 2-5× faster builds and up to 10× faster Fast Refresh. The release includes filesystem caching for development, stable React Compiler support for automatic memoization, and enhanced routing with layout deduplication and incremental prefetching. New caching APIs include updateTag() for read-your-writes semantics and refresh() for uncached data. Breaking changes include async-only params/searchParams access, middleware.ts renamed to proxy.ts, and React 19.2 integration with View Transitions and useEffectEvent. The framework shifts to explicit, opt-in caching by default, with all dynamic code executing at request time unless explicitly cached.