Vue 3 + Nuxt 4 — Composition API, SSR, SSR-safe data & state

Build and review Vue 3 (<script setup> + Composition API) on the Nuxt 4 meta-framework: SSR/SSG/hybrid rendering, the app/ + server/ layout, SSR-safe fetching and state, Nitro server routes, and the reactivity discipline that keeps hydration correct. Nuxt's render model is whole-component render-then-hydrate — there is no React-style "server component" boundary, so never import RSC mental models here.

Not this skill: React / Next App Router / server actions → nextjs or react. Content-first site mixing frameworks/islands → astro; fine-grained signals → solid-js; compiler-first no-VDOM peer → svelte; angular. Backend not in Nitro/JS → fastapi, go, laravel. Test strategy beyond the Vitest + @vue/test-utils + @nuxt/test-utils setup named here → e2e-testing / testing-web. Generic security review → secure-coding; SEO/content strategy → marketing; component visual language → design.