Vue 3 / Nuxt 3 Development Skill

File Organization: This skill uses split structure. See references/ for advanced patterns and security examples.

1. Overview

This skill provides expertise for building the JARVIS AI Assistant user interface using Vue 3 and Nuxt 3. It focuses on creating responsive, performant 3D HUD interfaces with security-first development practices.

Risk Level: MEDIUM - Handles user input, renders dynamic content, potential XSS vectors

Primary Use Cases:

• Building reactive 3D HUD components for JARVIS interface
• Server-side rendering for initial load performance
• Client-side state management integration
• Secure handling of user inputs and API responses

2. Core Responsibilities

2.1 Fundamental Principles

1. TDD First: Write tests before implementation - red/green/refactor cycle
2. Performance Aware: Use computed, shallowRef, lazy components for optimal reactivity
3. Composition API First: Use Vue 3 Composition API with <script setup> for better TypeScript inference and code organization
4. Server-Side Security: Leverage Nuxt's server routes for sensitive operations, never expose secrets to client
5. Reactive State Safety: Use ref() and reactive() with proper typing to prevent state corruption
6. Input Sanitization: Always sanitize user inputs before rendering or processing
7. Performance Optimization: Implement lazy loading, code splitting, and efficient reactivity for 3D HUD performance
8. Type Safety: Enforce TypeScript throughout for compile-time error detection
9. Secure Defaults: Configure CSP headers, disable dangerous features by default

3. Technology Stack & Versions

3.1 Recommended Versions

Package	Version	Security Notes
Vue	^3.4.0	Latest stable with improved reactivity
Nuxt	^3.12.4+	CRITICAL: Fixes CVE-2024-34344 RCE
@nuxt/devtools	^1.3.9+	CRITICAL: Fixes CVE-2024-23657
vite	^5.0.0	Latest with security patches

3.2 Security-Critical Dependencies

{
  "dependencies": {
    "nuxt": "^3.12.4",
    "vue": "^3.4.0",
    "dompurify": "^3.0.6",
    "isomorphic-dompurify": "^2.0.0"
  },
  "devDependencies": {
    "@nuxt/devtools": "^1.3.9",
    "eslint-plugin-vue": "^9.0.0",
    "eslint-plugin-security": "^2.0.0"
  }
}

4. Implementation Patterns

4.1 Secure Component Structure

<script setup lang="ts">
// ✅ Type-safe props with validation
interface Props {
  hudData: HUDDisplayData
  userId: string
}

const props = defineProps<Props>()

// ✅ Emit events with typed payloads
const emit = defineEmits<{
  'update:status': [status: string]
  'command:execute': [command: JARVISCommand]
}>()

// ✅ Secure ref initialization
const displayState = ref<HUDState>({
  isActive: false,
  securityLevel: 'standard'
})
</script>

<template>
  <!-- ✅ Use v-text for user content to prevent XSS -->
  <div class="hud-panel">
    <span v-text="props.hudData.title" />
  </div>
</template>

4.2 Input Sanitization Pattern

// composables/useSanitize.ts
import DOMPurify from 'isomorphic-dompurify'

export function useSanitize() {
  const sanitizeHTML = (dirty: string): string => {
    // ✅ Strict sanitization for any HTML content
    return DOMPurify.sanitize(dirty, {
      ALLOWED_TAGS: ['b', 'i', 'em', 'strong', 'span'],
      ALLOWED_ATTR: ['class']
    })
  }

  const sanitizeText = (input: string): string => {
    // ✅ Strip all HTML for plain text
    return DOMPurify.sanitize(input, { ALLOWED_TAGS: [] })
  }

  return { sanitizeHTML, sanitizeText }
}

4.3 Secure API Route Pattern

// server/api/jarvis/command.post.ts
import { z } from 'zod'

// ✅ Define strict schema for command validation
const commandSchema = z.object({
  action: z.enum(['status', 'control', 'query']),
  target: z.string().max(100).regex(/^[a-zA-Z0-9-_]+$/),
  parameters: z.record(z.string()).optional()
})

export default defineEventHandler(async (event) => {
  const body = await readBody(event)

  // ✅ Validate input against schema
  const result = commandSchema.safeParse(body)
  if (!result.success) {
    throw createError({
      statusCode: 400,
      message: 'Invalid command format'  // ✅ Generic error message
    })
  }

  // ✅ Process validated command
  const command = result.data

  // Never log sensitive data
  console.log(`Processing command: ${command.action}`)

  return { success: true, commandId: generateSecureId() }
})

4.4 Secure Environment Configuration

// nuxt.config.ts
export default defineNuxtConfig({
  // ✅ Security headers
  routeRules: {
    '/**': {
      headers: {
        'Content-Security-Policy': "default-src 'self'; script-src 'self' 'unsafe-inline'; style-src 'self' 'unsafe-inline'",
        'X-Content-Type-Options': 'nosniff',
        'X-Frame-Options': 'DENY',
        'X-XSS-Protection': '1; mode=block'
      }
    }
  },

  // ✅ Runtime config - secrets stay server-side
  runtimeConfig: {
    apiSecret: process.env.API_SECRET,  // Server only
    public: {
      apiBase: '/api'  // Client accessible
    }
  },

  // ✅ Disable devtools in production
  devtools: { enabled: process.env.NODE_ENV === 'development' }
})

4.5 3D HUD Component Integration

<script setup lang="ts">
// components/HUDDisplay.vue
import { TresCanvas } from '@tresjs/core'

const props = defineProps<{
  metrics: SystemMetrics
}>()

// ✅ Validate metrics before rendering
const validatedMetrics = computed(() => {
  return {
    cpu: Math.min(100, Math.max(0, props.metrics.cpu)),
    memory: Math.min(100, Math.max(0, props.metrics.memory)),
    status: sanitizeText(props.metrics.status)
  }
})
</script>

<template>
  <TresCanvas>
    <HUDMetricsDisplay :data="validatedMetrics" />
  </TresCanvas>
</template>

5. Implementation Workflow (TDD)

5.1 Step 1: Write Failing Test First

Always start by writing tests that define expected behavior:

// tests/components/VoiceIndicator.test.ts
import { describe, it, expect } from 'vitest'
import { mount } from '@vue/test-utils'
import VoiceIndicator from '@/components/VoiceIndicator.vue'

describe('VoiceIndicator', () => {
  it('displays idle state by default', () => {
    const wrapper = mount(VoiceIndicator)
    expect(wrapper.find('.indicator').classes()).toContain('idle')
    expect(wrapper.text()).toContain('Ready')
  })

  it('shows listening state when active', async () => {
    const wrapper = mount(VoiceIndicator, {
      props: { isListening: true }
    })
    expect(wrapper.find('.indicator').classes()).toContain('listening')
    expect(wrapper.find('.pulse-animation').exists()).toBe(true)
  })

  it('emits cancel event on escape key', async () => {
    const wrapper = mount(VoiceIndicator, {
      props: { isListening: true }
    })
    await wrapper.trigger('keydown.escape')
    expect(wrapper.emitted('cancel')).toBeTruthy()
  })
})

5.2 Step 2: Implement Minimum to Pass

Write only enough code to make the tests pass:

<script setup lang="ts">
const props = defineProps<{ isListening?: boolean }>()
const emit = defineEmits<{ 'cancel': [] }>()

const handleKeydown = (e: KeyboardEvent) => {
  if (e.key === 'Escape') emit('cancel')
}
</script>

<template>
  <div
    class="indicator"
    :class="isListening ? 'listening' : 'idle'"
    @keydown="handleKeydown"
    tabindex="0"
  >
    <span v-if="!isListening">Ready</span>
    <div v-else class="pulse-animation" />
  </div>
</template>

5.3 Step 3: Refactor if Needed

After tests pass, improve code quality without changing behavior. Re-run tests after each refactor.

5.4 Step 4: Run Full Verification

# Run all verification steps before committing
npx vitest run                    # Unit tests
npx eslint . --ext .vue,.ts       # Linting
npx nuxi typecheck                # Type checking
npm run build                     # Build verification

6. Performance Patterns

6.1 Computed Properties for Derived State

// ❌ BAD - Recalculates in template on every render
<template>
  <div>{{ items.filter(i => i.active).length }} active</div>
</template>

// ✅ GOOD - Cached until dependencies change
const activeCount = computed(() => items.value.filter(i => i.active).length)
<template>
  <div>{{ activeCount }} active</div>
</template>

6.2 shallowRef for Large Objects

// ❌ BAD - Deep reactivity on large 3D data
const meshData = ref<MeshData>({ vertices: new Float32Array(100000), ... })

// ✅ GOOD - Shallow reactivity, manual trigger
const meshData = shallowRef<MeshData>({ vertices: new Float32Array(100000), ... })
// Trigger update explicitly
meshData.value = { ...newData }
triggerRef(meshData)

6.3 defineAsyncComponent for Lazy Loading

// ❌ BAD - All components loaded upfront
import HeavyChart from '@/components/HeavyChart.vue'

// ✅ GOOD - Load only when needed
const HeavyChart = defineAsyncComponent(() =>
  import('@/components/HeavyChart.vue')
)

// With loading state
const HeavyChart = defineAsyncComponent({
  loader: () => import('@/components/HeavyChart.vue'),
  loadingComponent: LoadingSpinner,
  delay: 200
})

6.4 v-memo for List Optimization

<!-- ❌ BAD - Re-renders all items on any change -->
<div v-for="item in items" :key="item.id">
  <ExpensiveComponent :data="item" />
</div>

<!-- ✅ GOOD - Skip re-render if item unchanged -->
<div v-for="item in items" :key="item.id" v-memo="[item.id, item.updated]">
  <ExpensiveComponent :data="item" />
</div>

6.5 Virtual Scrolling for Long Lists

<script setup lang="ts">
import { useVirtualList } from '@vueuse/core'

const { list, containerProps, wrapperProps } = useVirtualList(
  items,
  { itemHeight: 50 }
)
</script>

<template>
  <!-- ✅ Only renders visible items -->
  <div v-bind="containerProps" class="h-[400px] overflow-auto">
    <div v-bind="wrapperProps">
      <div v-for="{ data, index } in list" :key="index">
        {{ data.name }}
      </div>
    </div>
  </div>
</template>

6.6 Debounced Watchers

// ❌ BAD - Fires on every keystroke
watch(searchQuery, async (query) => {
  results.value = await searchAPI(query)
})

// ✅ GOOD - Debounced to reduce API calls
import { watchDebounced } from '@vueuse/core'

watchDebounced(
  searchQuery,
  async (query) => {
    results.value = await searchAPI(query)
  },
  { debounce: 300 }
)

// Alternative with manual debounce
watch(searchQuery, useDebounceFn(async (query) => {
  results.value = await searchAPI(query)
}, 300))

7. Security Standards

7.1 Known Vulnerabilities (CVE Research)

CVE	Severity	Description	Mitigation
CVE-2024-34344	HIGH	Nuxt RCE via test component	Update to Nuxt 3.12.4+
CVE-2024-23657	HIGH	Devtools path traversal/RCE	Update devtools to 1.3.9+
CVE-2023-3224	CRITICAL	Dev server code injection	Update to Nuxt 3.4.4+, never expose dev server

See: references/security-examples.md for detailed mitigation code

5.2 OWASP Top 10 Coverage

OWASP Category	Risk	Mitigation Strategy
A01 Broken Access Control	HIGH	Server-side route guards, middleware auth
A03 Injection	HIGH	Input validation with Zod, parameterized queries
A05 Security Misconfiguration	MEDIUM	CSP headers, secure nuxt.config
A07 XSS	HIGH	v-text directive, DOMPurify sanitization

5.3 Input Validation Framework

// ❌ DANGEROUS - Direct v-html with user input
<div v-html="userMessage" />

// ✅ SECURE - Sanitized HTML or plain text
<div v-html="sanitizeHTML(userMessage)" />
<span v-text="userMessage" />

5.4 Authentication Middleware

// middleware/auth.ts
export default defineNuxtRouteMiddleware((to) => {
  const { authenticated } = useAuthState()

  if (!authenticated.value && to.meta.requiresAuth) {
    return navigateTo('/login')
  }
})

6. Testing & Quality

6.1 Security Testing

// tests/security/xss.test.ts
import { describe, it, expect } from 'vitest'
import { mount } from '@vue/test-utils'
import HUDPanel from '@/components/HUDPanel.vue'

describe('XSS Prevention', () => {
  it('should sanitize malicious input', () => {
    const wrapper = mount(HUDPanel, {
      props: {
        title: '<script>alert("xss")</script>Hello'
      }
    })

    expect(wrapper.html()).not.toContain('<script>')
    expect(wrapper.text()).toContain('Hello')
  })
})

6.2 Component Testing

// tests/components/HUDDisplay.test.ts
describe('HUDDisplay', () => {
  it('validates metric bounds', () => {
    const wrapper = mount(HUDDisplay, {
      props: {
        metrics: { cpu: 150, memory: -10, status: 'active' }
      }
    })

    // Should clamp values to valid range
    expect(wrapper.vm.validatedMetrics.cpu).toBe(100)
    expect(wrapper.vm.validatedMetrics.memory).toBe(0)
  })
})

7. Common Patterns / Workflows

7.1 JARVIS HUD Component Workflow

1. Define TypeScript interfaces for all data structures
2. Create composable for shared logic
3. Implement component with Composition API
4. Add input validation at component boundary
5. Write security tests for XSS/injection
6. Integrate with 3D scene via TresJS

7.2 API Integration Workflow

1. Define Zod schema for request/response
2. Create server route with validation
3. Implement client composable with error handling
4. Add loading/error states to UI
5. Test error cases and edge conditions

8. Common Mistakes & Anti-Patterns

8.1 Critical Security Anti-Patterns

Never: Use v-html with Unsanitized Input

<!-- ❌ DANGEROUS - XSS vulnerability -->
<div v-html="userProvidedContent" />

<!-- ✅ SECURE - Sanitized content -->
<div v-html="sanitizeHTML(userProvidedContent)" />

<!-- ✅ BEST - Plain text when HTML not needed -->
<span v-text="userProvidedContent" />

Never: Expose Secrets in Client Code

// ❌ DANGEROUS - Secret in public config
runtimeConfig: {
  public: {
    apiKey: process.env.API_KEY  // Exposed to client!
  }
}

// ✅ SECURE - Secrets stay server-side
runtimeConfig: {
  apiKey: process.env.API_KEY,  // Server only
  public: {
    apiBase: '/api'
  }
}

Never: Trust Client-Side Validation Alone

// ❌ DANGEROUS - Client-only validation
const handleSubmit = () => {
  if (isValidEmail(email.value)) {
    $fetch('/api/subscribe', { body: { email: email.value } })
  }
}

// ✅ SECURE - Server-side validation
// server/api/subscribe.post.ts
export default defineEventHandler(async (event) => {
  const body = await readBody(event)
  const result = emailSchema.safeParse(body)
  if (!result.success) {
    throw createError({ statusCode: 400, message: 'Invalid email' })
  }
  // Process validated email
})

8.2 Performance Anti-Patterns

Avoid: Reactive Arrays in Computed

// ❌ BAD - Creates new array on every access
const filtered = computed(() => {
  return items.value.filter(i => i.active).sort()
})

// ✅ GOOD - Memoized with stable reference
const filtered = computed(() => {
  const result = items.value.filter(i => i.active)
  result.sort((a, b) => a.name.localeCompare(b.name))
  return result
})

9. Quick Reference

Essential Commands

# Development
npx nuxi dev --host  # Never expose to public network!

# Security audit
npm audit --audit-level=high
npx nuxi typecheck

# Production build
npx nuxi build

Key Composables

// State management
const state = useState<T>('key', () => initialValue)

// Runtime config access
const config = useRuntimeConfig()

// Route navigation
const router = useRouter()
await navigateTo('/path')

13. Pre-Deployment Checklist

Security Verification

• Nuxt version >= 3.12.4 (CVE-2024-34344 fix)
• Devtools version >= 1.3.9 (CVE-2024-23657 fix)
• CSP headers configured in nuxt.config
• No secrets in runtimeConfig.public
• All user inputs sanitized with DOMPurify
• Server routes validate with Zod schemas
• Authentication middleware on protected routes
• Devtools disabled in production

Build Verification

• npm audit shows no high/critical vulnerabilities
• TypeScript compilation passes
• All security tests pass
• Production build completes without errors

14. Summary

This Vue/Nuxt skill provides secure patterns for building the JARVIS AI Assistant HUD interface:

1. Security First: Always sanitize inputs, validate on server, use CSP headers
2. Type Safety: TypeScript throughout with strict validation schemas
3. Performance: Composition API, lazy loading, efficient reactivity
4. Maintainability: Clear component structure, composables for reuse

Remember: The JARVIS HUD handles sensitive system data. Every component must treat user input as potentially malicious and validate all data boundaries.

---

References:

• references/advanced-patterns.md - Complex component patterns
• references/security-examples.md - Detailed security implementations