260223:1415 20260223 nextJS & nestJS Best pratices

.agents/skills/next-best-practices/directives.md

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+# Directives
+
+## React Directives
+
+These are React directives, not Next.js specific.
+
+### `'use client'`
+
+Marks a component as a Client Component. Required for:
+- React hooks (`useState`, `useEffect`, etc.)
+- Event handlers (`onClick`, `onChange`)
+- Browser APIs (`window`, `localStorage`)
+
+```tsx
+'use client'
+
+import { useState } from 'react'
+
+export function Counter() {
+  const [count, setCount] = useState(0)
+  return <button onClick={() => setCount(count + 1)}>{count}</button>
+}
+```
+
+Reference: https://react.dev/reference/rsc/use-client
+
+### `'use server'`
+
+Marks a function as a Server Action. Can be passed to Client Components.
+
+```tsx
+'use server'
+
+export async function submitForm(formData: FormData) {
+  // Runs on server
+}
+```
+
+Or inline within a Server Component:
+
+```tsx
+export default function Page() {
+  async function submit() {
+    'use server'
+    // Runs on server
+  }
+  return <form action={submit}>...</form>
+}
+```
+
+Reference: https://react.dev/reference/rsc/use-server
+
+---
+
+## Next.js Directive
+
+### `'use cache'`
+
+Marks a function or component for caching. Part of Next.js Cache Components.
+
+```tsx
+'use cache'
+
+export async function getCachedData() {
+  return await fetchData()
+}
+```
+
+Requires `cacheComponents: true` in `next.config.ts`.
+
+For detailed usage including cache profiles, `cacheLife()`, `cacheTag()`, and `updateTag()`, see the `next-cache-components` skill.
+
+Reference: https://nextjs.org/docs/app/api-reference/directives/use-cache