npm install
npm run dev

src/
  app/
    page.tsx            # Home page (Server Component), loads products server-side
    actions.ts           # Server Actions: addProductAction, togglePurchasedAction, deleteProductAction
    api/
      products/
        route.ts          # GET /api/products, POST /api/products
        [id]/route.ts      # GET/PATCH/DELETE /api/products/:id
      [transport]/
        route.ts          # MCP endpoint (Streamable HTTP), served at /api/mcp
  components/
    ProductForm.tsx        # Add-product form (uses a Server Action)
    ProductList.tsx        # List incl. toggle/delete (uses Server Actions)
  lib/
    productRepository.ts   # the only place that touches the filesystem (data/products.json)
    mcp/
      server.ts             # registers the MCP tools
      shoppingApiClient.ts   # MCP's only way to reach the data — calls the REST API, never the repository directly
  types/
    product.ts             # Product type

data/
  products.json            # data store (created automatically if missing)

interface Product {
  id: string;
  name: string;
  person: string;
  purchased: boolean;
  createdAt: string; // ISO date
}

getProducts()
getProductsByPerson(person)
getProductById(id)
addProduct(product)
updateProduct(id, changes)
deleteProduct(id)

GET /api/products
GET /api/products?person=Rinaldo   # filter by person, case-insensitive
GET /api/products/:id

POST /api/products
Content-Type: application/json

{ "name": "Milk", "person": "Rinaldo" }

PATCH /api/products/:id
Content-Type: application/json

{ "purchased": true }

DELETE /api/products/:id

{ "error": "Product not found" }

# Add a product
curl -X POST http://localhost:3000/api/products \
  -H "Authorization: Bearer $SHOPPING_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"name":"Milk","person":"Rinaldo"}'

# List a person's products
curl "http://localhost:3000/api/products?person=Rinaldo" \
  -H "Authorization: Bearer $SHOPPING_API_KEY"

# Mark a product as purchased
curl -X PATCH http://localhost:3000/api/products/PRODUCT_ID \
  -H "Authorization: Bearer $SHOPPING_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"purchased":true}'

# Delete a product
curl -X DELETE http://localhost:3000/api/products/PRODUCT_ID \
  -H "Authorization: Bearer $SHOPPING_API_KEY"

MCP client → MCP server → REST API → productRepository → data/products.json

npx @modelcontextprotocol/inspector --cli http://localhost:3000/api/mcp --method tools/list \
  --header "Authorization: Bearer $SHOPPING_API_KEY"

curl http://localhost:3000/api/products \
  -H "Authorization: Bearer $SHOPPING_API_KEY"