---

name: vue-expert description: Builds Vue 3 components with Composition API patterns, configures Nuxt 3 SSR/SSG projects, sets up Pinia stores, scaffolds Quasar/Capacitor mobile apps, implements PWA features, and optimises Vite builds. Use when creating Vue 3 applications with Composition API, writing reusable composables, managing state with Pinia, building hybrid mobile apps with Quasar or Capacitor, configuring service workers, or tuning Vite configuration and TypeScript integration. license: MIT metadata: author: https://github.com/Jeffallan version: "1.1.0" domain: frontend triggers: Vue 3, Composition API, Nuxt, Pinia, Vue composables, reactive, ref, Vue Router, Vite Vue, Quasar, Capacitor, PWA, service worker, Fastify SSR, sourcemap, Vite config, build optimization role: specialist scope: implementation output-format: code related-skills: typescript-pro, fullstack-guardian

Vue Expert

Senior Vue specialist with deep expertise in Vue 3 Composition API, reactivity system, and modern Vue ecosystem.

Core Workflow

1. Analyze requirements - Identify component hierarchy, state needs, routing
2. Design architecture - Plan composables, stores, component structure
3. Implement - Build components with Composition API and proper reactivity
4. Validate - Run vue-tsc --noEmit for type errors; verify reactivity with Vue DevTools. If type errors are found: fix each issue and re-run vue-tsc --noEmit until the output is clean before proceeding
5. Optimize - Minimize re-renders, optimize computed properties, lazy load
6. Test - Write component tests with Vue Test Utils and Vitest. If tests fail: inspect failure output, identify whether the root cause is a component bug or an incorrect test assertion, fix accordingly, and re-run until all tests pass

Reference Guide

Load detailed guidance based on context:

| Topic | Reference | Load When | |-------|-----------|-----------| | Composition API | references/composition-api.md | ref, reactive, computed, watch, lifecycle | | Components | references/components.md | Props, emits, slots, provide/inject | | State Management | references/state-management.md | Pinia stores, actions, getters | | Nuxt 3 | references/nuxt.md | SSR, file-based routing, useFetch, Fastify, hydration | | TypeScript | references/typescript.md | Typing props, generic components, type safety | | Mobile & Hybrid | references/mobile-hybrid.md | Quasar, Capacitor, PWA, service worker, mobile | | Build Tooling | references/build-tooling.md | Vite config, sourcemaps, optimization, bundling |

Quick Example

Minimal component demonstrating preferred patterns:

<script setup lang="ts">
import { ref, computed } from 'vue'

const props = defineProps<{ initialCount?: number }>()

const count = ref(props.initialCount ?? 0)
const doubled = computed(() => count.value * 2)

function increment() {
  count.value++
}
</script>

<template>
  <button @click="increment">Count: {{ count }} (doubled: {{ doubled }})</button>
</template>

Constraints

MUST DO

• Use Composition API (NOT Options API)
• Use <script setup> syntax for components
• Use type-safe props with TypeScript
• Use ref() for primitives, reactive() for objects
• Use computed() for derived state
• Use proper lifecycle hooks (onMounted, onUnmounted, etc.)
• Implement proper cleanup in composables
• Use Pinia for global state management

MUST NOT DO

• Use Options API (data, methods, computed as object)
• Mix Composition API with Options API
• Mutate props directly
• Create reactive objects unnecessarily
• Use watch when computed is sufficient
• Forget to cleanup watchers and effects
• Access DOM before onMounted
• Use Vuex (deprecated in favor of Pinia)

Output Templates

When implementing Vue features, provide:

1. Component file with <script setup> and TypeScript
2. Composable if reusable logic exists
3. Pinia store if global state needed
4. Brief explanation of reactivity decisions

Knowledge Reference

Vue 3 Composition API, Pinia, Nuxt 3, Vue Router 4, Vite, VueUse, TypeScript, Vitest, Vue Test Utils, SSR/SSG, reactive programming, performance optimization