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name: nextjs-core description: Core Next.js patterns for App Router development including Server Components, Server Actions, route handlers, data fetching, and caching strategies version: 1.1.0 category: toolchain progressive_disclosure: entry_point: summary: "Server-first patterns with safe mutations (Server Actions) and explicit caching/revalidation" tags: [nextjs, app-router]

Next.js Core (App Router)

• Server Components by default; minimal "use client".
• Mutations in Server Actions (validate/authz; revalidate tags/paths).
• Route handlers for APIs/webhooks; add loading/error boundaries.

Anti-patterns:

• ❌ Fetch initial data in useEffect.
• ❌ Cache or revalidate too broadly.
• ❌ Client-only authz.

References: see references/ (server actions, fetching, caching, routing, auth, testing).