I need the exact TypeScript definition for the Commerce Engine Cart type.
Fetch it from: curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/schemas/Cart

Then show me how to import and use this type in my code. Remember: always import directly from the SDK package as a named export, never define custom interfaces:

import type { Cart } from "@commercengine/storefront-sdk";

I need the exact TypeScript signature and usage example for the createCart SDK method.
Fetch it from: curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/operations/create-cart

Show me the full method call with proper typing. Import operation types directly from the SDK:

import type { CreateCartBody, CreateCartContent } from "@commercengine/storefront-sdk";

Set up the Commerce Engine TypeScript SDK for a client-side React app.

Requirements:
- Use @commercengine/storefront-sdk
- Use BrowserTokenStorage for automatic token persistence
- Use environment variables for storeId and apiKey (REACT_APP_ prefix)
- Export the SDK instance from lib/storefront.ts
- Include onTokensUpdated and onTokensCleared callbacks

Reference: https://llm-docs.commercengine.io/sdk/
Fetch with: curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/operations/anonymous-user

Set up the Commerce Engine Next.js SDK for an App Router project.

Requirements:
- Use @commercengine/storefront-sdk-nextjs
- Create lib/storefront.ts that re-exports the storefront function
- Add StorefrontSDKInitializer to the root layout
- Show how to use storefront() in client components (no cookies)
- Show how to use storefront(cookies()) in server components
- Use NEXT_PUBLIC_STORE_ID and NEXT_PUBLIC_API_KEY env vars

Reference: https://llm-docs.commercengine.io/sdk/

Set up the Commerce Engine SDK for a Node.js Express backend.

Requirements:
- Use @commercengine/storefront-sdk with MemoryTokenStorage
- Configure for server-side usage with proper timeout
- Show middleware that creates per-request SDK instances with user tokens
- Include health check endpoint using sdk.helpers.retrieveAllCountries()

Reference: https://llm-docs.commercengine.io/sdk/

Implement a complete email OTP login flow using the Commerce Engine SDK.

Steps:
1. Call sdk.auth.loginWithEmail({ email, register_if_not_exists: true })
2. Show OTP input UI
3. Call sdk.auth.verifyOtp({ otp, otp_token, otp_action }) with the tokens from step 1
4. Tokens are automatically managed by the SDK after verification

Requirements:
- Handle both login and registration (register_if_not_exists: true)
- Show loading states
- Handle errors for each step (invalid email, wrong OTP, expired OTP)
- Use the { data, error } pattern, not try/catch

Reference: fetch these for exact signatures:
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/operations/login-with-email
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/operations/verify-otp

Implement a phone number OTP login flow using the Commerce Engine SDK.

Steps:
1. Call sdk.auth.loginWithPhone({ phone, country_code, register_if_not_exists: true })
2. Show OTP input UI
3. Call sdk.auth.verifyOtp({ otp, otp_token, otp_action })

Requirements:
- Include country code selector
- Handle errors for each step
- Use { data, error } pattern

Reference: fetch these for exact signatures:
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/operations/login-with-phone
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/operations/verify-otp

Implement Commerce Engine authentication as Next.js Server Actions.

Requirements:
- Create server actions for: sendOTP (email), verifyOTP, logout
- Use storefront(cookies()) in every server action for token persistence
- Use redirect() after successful auth
- IMPORTANT: Auth endpoints that return tokens MUST be in Server Actions, NOT Server Components
- Handle errors and return them to the client

Reference: https://llm-docs.commercengine.io/sdk/

Build a product listing page using the Commerce Engine SDK.

Requirements:
- Fetch products with sdk.catalog.listProducts()
- Support pagination (page, limit query params)
- Support filtering by category_id
- Display: product name, image, selling_price, slug
- Link each product to /products/[slug]
- Handle loading and error states
- Use { data, error } pattern
- Import types directly from SDK: import type { Product, ListProductsContent } from "@commercengine/storefront-sdk"
  - Never create custom Product interfaces — the SDK exports all schema types as named exports

Reference: fetch for exact response shape and TypeScript definitions:
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/operations/list-all-products
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/schemas/Product

Build a statically generated product detail page in Next.js App Router using Commerce Engine.

Requirements:
- Use generateStaticParams() to pre-render product pages from sdk.catalog.listProducts()
- Fetch product detail with sdk.catalog.getProduct({ product_id_or_slug: slug })
- Display: name, description, images, price, variants, availability
- Include AddToCart button component (client component)
- Use storefront() without cookies (build context uses memory storage)
- Configure NEXT_BUILD_CACHE_TOKENS=true in next.config.ts for efficient token reuse

Reference: fetch for exact response shape:
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/operations/retrieve-a-product-detail

Implement product search using the Commerce Engine SDK.

Requirements:
- Use sdk.catalog.searchProducts({ query: { q: searchTerm } })
- Debounce search input (300ms)
- Show search results with product name, image, price
- Handle empty results and errors
- Support keyboard navigation of results

Reference: fetch for exact signature:
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/operations/search-products

Build a complete shopping cart using the Commerce Engine SDK.

Requirements:
- Fetch cart with sdk.cart.retrieveCartUsingUserId(userId)
- Add items with sdk.cart.addDeleteCartItem(cartId, { product_id, variant_id, quantity })
- IMPORTANT: variant_id is ALWAYS required, pass null for products without variants
- Update quantity by calling addDeleteCartItem with new quantity
- Remove items by setting quantity to 0
- Display: items, quantities, selling_price, sub_total, tax_amount, shipping_amount, grand_total
- Delete entire cart with sdk.cart.deleteCart(cartId)
- Import types directly from SDK: import type { Cart, CartItem, UpdateCartItem } from "@commercengine/storefront-sdk"
  - Never create custom Cart or CartItem interfaces — the SDK exports all schema types as named exports

Reference: fetch for exact TypeScript definitions and signatures:
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/operations/adddelete-cart-item
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/schemas/Cart
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/schemas/UpdateCartItem

Implement coupon and promotion handling for the Commerce Engine cart.

Requirements:
- Apply coupon: sdk.cart.applyCoupon(cartId, { coupon_code: "CODE" })
- Remove coupon: sdk.cart.removeCoupon(cartId, { coupon_code: "CODE" })
- List available coupons: sdk.cart.retrieveAllCoupons()
- List available promotions: sdk.cart.retrieveAllPromotions()
- Show discount breakdown in cart summary
- Handle invalid/expired coupon errors

Reference: fetch for exact signatures:
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/operations/apply-coupon
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/operations/retrieve-all-coupons

Implement a checkout flow using the Commerce Engine SDK.

Steps:
1. Update cart address: sdk.cart.updateCartAddress(cartId, { shipping_address, billing_address })
2. Check fulfillment: sdk.cart.checkFulfillment(cartId)
3. Get fulfillment options: sdk.cart.retrieveFulfillmentOptions(cartId)
4. Update fulfillment preference: sdk.cart.updateFulfillmentPreference(cartId, { ... })
5. Create order: sdk.order.createOrder({ ... })
6. Check payment status: sdk.order.retrievePaymentStatus(orderId)

Requirements:
- Multi-step form with address, shipping method, payment, review
- Handle errors at each step
- Show order summary with totals

Reference: fetch for exact signatures:
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/operations/create-order
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/operations/update-cart-address

Build a customer profile/account page using the Commerce Engine SDK.

Requirements:
- Fetch user: sdk.auth.retrieveUser()
- Fetch customer: sdk.customer.retrieveCustomerDetail(userId)
- Update customer: sdk.customer.updateCustomerDetail(userId, { ... })
- Manage addresses: sdk.customer.retrieveAllAddresses(userId), createAddress, updateParticularAddress, removeParticularAddress
- Show order history: sdk.order.retrieveAllOrders()
- Check loyalty points: sdk.customer.retrieveLoyaltyDetails(userId)

Reference: fetch for exact signatures:
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/operations/retrieve-a-user
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/operations/retrieve-all-addresses

Set up webhook handlers for Commerce Engine order events.

Requirements:
- Handle these webhook events: order.created, order.confirmed, order.cancelled, payment.successful, payment.failed, shipment.created, shipment.delivered
- Verify webhook signatures
- Process events asynchronously (queue for background processing)
- Return 200 quickly to acknowledge receipt
- Log webhook payloads for debugging

Reference: fetch for webhook payload schemas:
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/webhooks/
  curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/webhooks/order.created

Scaffold a complete Next.js App Router storefront using Commerce Engine.

Requirements:
- Use @commercengine/storefront-sdk-nextjs
- Pages: Home, Product List, Product Detail, Cart, Checkout, Account, Orders
- Auth: Email OTP login via Server Actions
- SSG: Pre-render product pages with generateStaticParams
- Cart: Client-side cart with optimistic updates
- Layout: StorefrontSDKInitializer in root layout
- Token caching: NEXT_BUILD_CACHE_TOKENS=true for build optimization
- Error handling: Use { data, error } pattern everywhere

Full SDK reference: https://llm-docs.commercengine.io/
API operations: https://llm-docs.commercengine.io/operations/

Create a complete React context and hooks setup for Commerce Engine.

Requirements:
- CommerceProvider: Shares SDK instance via context
- AuthProvider: Manages auth state (user, isLoggedIn, login, logout)
- useCart hook: cart state, addItem, updateItem, removeItem, clearCart, itemCount
- useProducts hook: fetch products with filters, pagination, loading state
- All hooks use { data, error } pattern from SDK
- Import ALL types directly from the SDK — never define custom interfaces:
  import type { Cart, Product, CartItem, UpdateCartItem } from "@commercengine/storefront-sdk";
  import type { CreateCartBody, ListProductsContent } from "@commercengine/storefront-sdk";

Reference: https://llm-docs.commercengine.io/sdk/
Fetch type definitions: curl -H "Accept: text/markdown" https://llm-docs.commercengine.io/storefront/schemas/Cart