Static-first Next.js 16 architecture patterns: cached shells with dynamic slots, provider islands, 'use cache' boundaries, and link preloading strategy. Use when building or refactoring Next.js routes to maximize static rendering, implementing 'use cache' with dynamic personalization, splitting entry vs static renderers, scoping client providers, or tuning prefetch behavior. Triggers on 'static shell', 'use cache pattern', 'dynamic slots', 'provider island', 'prefetch strategy', 'static first', 'cache boundary', 'route goes dynamic unexpectedly', or any Next.js architecture work involving mixed static/dynamic rendering.