chore: init monorepo with existing website and plans

.agents/skills/vue-debug-guides/reference/sfc-named-exports-forbidden.md

@@ -0,0 +1,184 @@
+---
+title: SFC Script Block Must Use Default Export Only
+impact: HIGH
+impactDescription: Named exports in SFC script blocks will fail silently or cause build errors - Vue expects exactly one default export
+type: gotcha
+tags: [vue3, sfc, export, script-block, composition-api]
+---
+
+# SFC Script Block Must Use Default Export Only
+
+**Impact: HIGH** - Vue Single-File Components expect exactly one default export from the `<script>` block. Using named exports for your component will cause build failures or runtime errors because Vue's tooling is designed to process a single default-exported component definition per `.vue` file.
+
+## Task Checklist
+
+- [ ] Always use `export default` in `<script>` blocks (Options API)
+- [ ] Use `<script setup>` which handles exports automatically (Composition API)
+- [ ] Move shared utilities to separate `.js`/`.ts` files, not the component's script block
+- [ ] If you need to export types, use a separate `<script>` block alongside `<script setup>`
+
+**Problematic Code:**
+```vue
+<!-- MyComponent.vue -->
+<script>
+// BAD: Named exports don't work for the component itself
+export const MyComponent = {
+  data() {
+    return { count: 0 }
+  }
+}
+
+// BAD: Exporting multiple things from component script
+export const CONSTANT = 42
+export function helper() { }
+</script>
+
+<template>
+  <div>{{ count }}</div>
+</template>
+```
+
+**Correct Code:**
+```vue
+<!-- MyComponent.vue - Options API -->
+<script>
+// GOOD: Single default export
+export default {
+  data() {
+    return { count: 0 }
+  }
+}
+</script>
+
+<template>
+  <div>{{ count }}</div>
+</template>
+```
+
+```vue
+<!-- MyComponent.vue - Composition API with script setup -->
+<script setup>
+// GOOD: No export needed, component is auto-exported
+import { ref } from 'vue'
+
+const count = ref(0)
+</script>
+
+<template>
+  <div>{{ count }}</div>
+</template>
+```
+
+## Exporting Types Alongside Script Setup
+
+For TypeScript, use a separate regular script block for type exports:
+
+```vue
+<script lang="ts">
+// Regular script block for exports
+export interface User {
+  id: number
+  name: string
+}
+
+export type Status = 'pending' | 'active' | 'inactive'
+</script>
+
+<script setup lang="ts">
+// Setup script for component logic
+import { ref } from 'vue'
+
+const users = ref<User[]>([])
+</script>
+
+<template>
+  <ul>
+    <li v-for="user in users" :key="user.id">{{ user.name }}</li>
+  </ul>
+</template>
+```
+
+## Sharing Utilities Across Components
+
+Don't put shared code in component script blocks. Create separate files:
+
+```typescript
+// utils/constants.ts
+export const ITEMS_PER_PAGE = 20
+export const API_BASE_URL = '/api/v1'
+
+// utils/helpers.ts
+export function formatDate(date: Date): string {
+  return date.toLocaleDateString()
+}
+
+export function formatCurrency(amount: number): string {
+  return `$${amount.toFixed(2)}`
+}
+```
+
+```vue
+<!-- ProductList.vue -->
+<script setup>
+// GOOD: Import shared utilities from external files
+import { ITEMS_PER_PAGE } from '@/utils/constants'
+import { formatCurrency } from '@/utils/helpers'
+import { ref } from 'vue'
+
+const products = ref([])
+</script>
+```
+
+## Why This Restriction Exists
+
+Vue's SFC compiler and build tools expect:
+
+1. **One component per file**: The `.vue` file format is designed for single-component definitions
+2. **Predictable structure**: Tools like Volar, vue-tsc, and bundler plugins assume default export
+3. **Hot Module Replacement**: HMR relies on the single-component-per-file convention
+
+```javascript
+// How Vue tooling processes SFCs internally
+import MyComponent from './MyComponent.vue'
+// ^ Always expects the default export to be the component
+```
+
+## Common Mistake: Reusing Code via SFC Exports
+
+```vue
+<!-- BAD PATTERN: Trying to reuse code from components -->
+<script>
+// This won't work as expected
+export const sharedLogic = () => { ... }
+
+export default {
+  // component definition
+}
+</script>
+```
+
+Instead, use composables:
+
+```typescript
+// composables/useSharedLogic.ts
+export function useSharedLogic() {
+  // Shared reactive logic
+  const state = ref(0)
+  const increment = () => state.value++
+
+  return { state, increment }
+}
+```
+
+```vue
+<!-- ComponentA.vue -->
+<script setup>
+import { useSharedLogic } from '@/composables/useSharedLogic'
+
+const { state, increment } = useSharedLogic()
+</script>
+```
+
+## Reference
+- [Vue.js SFC Specification](https://vuejs.org/api/sfc-spec.html)
+- [Vue.js Composition API - Composables](https://vuejs.org/guide/reusability/composables.html)