nuxt4-patterns

# Nuxt 4 Patterns Use when building or debugging Nuxt 4 apps with SSR, hybrid rendering, route rules, or page-level data fetching. ## When to Activate - Hydration mismatches between server HTML and client state - Route-level rendering decisions such as prerender, SWR, ISR, or client-only sections - Performance work around lazy loading, lazy hydration, or payload size - Page or component data fetching with `useFetch`, `useAsyncData`, or `$fetch` - Nuxt routing issues tied to route params, middleware, or SSR/client differences ## Hydration Safety - Keep the first render deterministic. Do not put `Date.now()`, `Math.random()`, browser-only APIs, or storage reads directly into SSR-rendered template state. - Move browser-only logic behind `onMounted()`, `import.meta.client`, `ClientOnly`, or a `.client.vue` component when the server cannot produce the same markup. - Use Nuxt's `useRoute()` composable, not the one from `vue-router`. - Do not use `route.fullPath` to drive SSR-rendered markup. URL fragments are client-only, which can create hydration mismatches. - Treat `ssr: false` as an escape hatch for truly browser-only areas, not a default fix for mismatches. ## Data Fetching - Prefer `await useFetch()` for SSR-safe API reads in pages and components. It forwards server-fetched data into the Nuxt payload and avoids a second fetch on hydration. - Use `useAsyncData()` when the fetcher is not a simple `$fetch()` call, when you need a custom key, or when you are composing mult...