Shopify Development Expert

Purpose

Provide comprehensive, accurate guidance for building on Shopify’s platform based on 24+ official documentation files. Cover all aspects of app development, theme customization, API integration, checkout extensions, and e-commerce features.

Documentation Coverage

Full access to official Shopify documentation (when available):

• Location: docs/shopify/
• Files: 25 markdown files
• Coverage: Complete API reference, guides, best practices, and implementation patterns

Note: Documentation must be pulled separately:

pipx install docpull
docpull https://shopify.dev/docs -o .claude/skills/shopify/docs

Major Areas:

• GraphQL Admin API (products, orders, customers, inventory)
• Storefront API (cart, checkout, customer accounts)
• REST Admin API (legacy support)
• App development (authentication, webhooks, extensions)
• Theme development (Liquid, sections, blocks)
• Headless commerce (Hydrogen, Oxygen)
• Checkout customization (UI extensions, validation)
• Shopify Functions (discounts, delivery, payments)
• POS extensions (in-person sales)
• Subscriptions and selling plans
• Metafields and custom data
• Shopify Flow automation
• CLI and development tools
• Privacy and compliance
• Performance optimization

When to Use

Invoke when user mentions:

• Platform: Shopify, e-commerce, online store, merchant
• APIs: GraphQL, REST, Storefront API, Admin API
• Products: product management, collections, variants, inventory
• Orders: order processing, fulfillment, shipping
• Customers: customer data, accounts, authentication
• Checkout: checkout customization, payment methods, delivery options
• Themes: Liquid templates, theme development, sections, blocks
• Apps: app development, extensions, webhooks, OAuth
• Headless: Hydrogen, React, headless commerce, Oxygen
• Functions: Shopify Functions, custom logic, discounts
• Subscriptions: recurring billing, selling plans, subscriptions
• Tools: Shopify CLI, development workflow
• POS: point of sale, retail, in-person payments

How to Use Documentation

When answering questions:

1. Search for specific topics:

   # Use Grep to find relevant docs
   grep -r "checkout" .claude/skills/shopify/docs/ --include="*.md"
   

2. Read specific documentation:

   # API docs
   cat .claude/skills/shopify/docs/shopify/api-admin-graphql.md
   cat .claude/skills/shopify/docs/shopify/api-storefront.md
   

3. Find implementation guides:

   # List all guides
   ls .claude/skills/shopify/docs/shopify/
   

Core Authentication

OAuth 2.0 Flow

// Redirect to Shopify OAuth
const authUrl = `https://${shop}/admin/oauth/authorize?` +
  `client_id=${process.env.SHOPIFY_API_KEY}&` +
  `scope=read_products,write_products&` +
  `redirect_uri=${redirectUri}&` +
  `state=${nonce}`;

// Exchange code for access token
const response = await fetch(
  `https://${shop}/admin/oauth/access_token`,
  {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      client_id: process.env.SHOPIFY_API_KEY,
      client_secret: process.env.SHOPIFY_API_SECRET,
      code
    })
  }
);

const { access_token } = await response.json();

Session Tokens (Modern Embedded Apps)

import { shopifyApi } from '@shopify/shopify-api';

const shopify = shopifyApi({
  apiKey: process.env.SHOPIFY_API_KEY,
  apiSecretKey: process.env.SHOPIFY_API_SECRET,
  scopes: ['read_products', 'write_products'],
  hostName: process.env.HOST,
  isEmbeddedApp: true,
});

GraphQL Admin API

Query Products

query {
  products(first: 10) {
    edges {
      node {
        id
        title
        handle
        priceRange {
          minVariantPrice {
            amount
            currencyCode
          }
        }
        variants(first: 5) {
          edges {
            node {
              id
              sku
              inventoryQuantity
            }
          }
        }
      }
    }
  }
}

Create Product

mutation {
  productCreate(input: {
    title: "New Product"
    vendor: "My Store"
    productType: "Apparel"
    variants: [{
      price: "29.99"
      sku: "PROD-001"
    }]
  }) {
    product {
      id
      title
    }
    userErrors {
      field
      message
    }
  }
}

Fetch Orders

query {
  orders(first: 25, query: "fulfillment_status:unfulfilled") {
    edges {
      node {
        id
        name
        createdAt
        totalPriceSet {
          shopMoney {
            amount
            currencyCode
          }
        }
        customer {
          email
        }
        lineItems(first: 10) {
          edges {
            node {
              title
              quantity
            }
          }
        }
      }
    }
  }
}

Storefront API

Create Cart

mutation {
  cartCreate(input: {
    lines: [{
      merchandiseId: "gid://shopify/ProductVariant/123"
      quantity: 1
    }]
  }) {
    cart {
      id
      checkoutUrl
      cost {
        totalAmount {
          amount
          currencyCode
        }
      }
    }
  }
}

Update Cart

mutation {
  cartLinesUpdate(
    cartId: "gid://shopify/Cart/xyz"
    lines: [{
      id: "gid://shopify/CartLine/abc"
      quantity: 2
    }]
  ) {
    cart {
      id
      lines(first: 10) {
        edges {
          node {
            quantity
          }
        }
      }
    }
  }
}

Webhooks

Setup Webhook

// Register webhook via API
const webhook = await shopify.webhooks.register({
  topic: 'ORDERS_CREATE',
  address: 'https://your-app.com/webhooks/orders-create',
  format: 'json'
});

Verify Webhook

import crypto from 'crypto';

function verifyWebhook(body, hmacHeader, secret) {
  const hash = crypto
    .createHmac('sha256', secret)
    .update(body, 'utf8')
    .digest('base64');

  return hash === hmacHeader;
}

// In webhook handler
app.post('/webhooks/orders-create', async (req, res) => {
  const hmac = req.headers['x-shopify-hmac-sha256'];
  const body = await req.text();

  if (!verifyWebhook(body, hmac, process.env.SHOPIFY_API_SECRET)) {
    return res.status(401).send('Invalid HMAC');
  }

  const order = JSON.parse(body);
  // Process order...

  res.status(200).send('OK');
});

Liquid Templates

Basic Liquid

<!-- Output product title -->
{{ product.title }}

<!-- Conditional logic -->
{% if product.available %}
  <button>Add to Cart</button>
{% else %}
  <span>Sold Out</span>
{% endif %}

<!-- Loop through variants -->
{% for variant in product.variants %}
  <option value="{{ variant.id }}">
    {{ variant.title }} - {{ variant.price | money }}
  </option>
{% endfor %}

Custom Section

{% schema %}
{
  "name": "Featured Product",
  "settings": [
    {
      "type": "product",
      "id": "product",
      "label": "Product"
    }
  ]
}
{% endschema %}

{% if section.settings.product %}
  {% assign product = section.settings.product %}
  <div class="featured-product">
    <img src="{{ product.featured_image | img_url: '500x' }}" alt="{{ product.title }}">
    <h2>{{ product.title }}</h2>
    <p>{{ product.price | money }}</p>
  </div>
{% endif %}

Shopify Functions

Discount Function

// Function to apply volume discount
export default (input) => {
  const quantity = input.cart.lines.reduce((sum, line) => sum + line.quantity, 0);

  let discountPercentage = 0;
  if (quantity >= 10) discountPercentage = 20;
  else if (quantity >= 5) discountPercentage = 10;

  if (discountPercentage > 0) {
    return {
      discounts: [{
        message: `${discountPercentage}% volume discount`,
        targets: [{
          orderSubtotal: {
            excludedVariantIds: []
          }
        }],
        value: {
          percentage: {
            value: discountPercentage.toString()
          }
        }
      }]
    };
  }

  return { discounts: [] };
};

Delivery Customization

// Hide specific delivery options
export default (input) => {
  const operations = [];

  // Hide express shipping for orders under $100
  const cartTotal = parseFloat(input.cart.cost.subtotalAmount.amount);

  if (cartTotal < 100) {
    const expressOptions = input.cart.deliveryGroups[0].deliveryOptions
      .filter(option => option.title.toLowerCase().includes('express'));

    expressOptions.forEach(option => {
      operations.push({
        hide: {
          deliveryOptionHandle: option.handle
        }
      });
    });
  }

  return { operations };
};

Hydrogen (Headless Commerce)

Product Page

// app/routes/products.$handle.tsx
import {json, LoaderFunctionArgs} from '@shopify/remix-oxygen';
import {useLoaderData} from '@remix-run/react';

export async function loader({params, context}: LoaderFunctionArgs) {
  const {product} = await context.storefront.query(PRODUCT_QUERY, {
    variables: {handle: params.handle},
  });

  return json({product});
}

export default function Product() {
  const {product} = useLoaderData<typeof loader>();

  return (
    <div>
      <h1>{product.title}</h1>
      <img src={product.featuredImage.url} alt={product.title} />
      <p>{product.description}</p>
      <AddToCartButton productId={product.id} />
    </div>
  );
}

const PRODUCT_QUERY = `#graphql
  query Product($handle: String!) {
    product(handle: $handle) {
      id
      title
      description
      featuredImage {
        url
        altText
      }
      variants(first: 10) {
        nodes {
          id
          price {
            amount
            currencyCode
          }
        }
      }
    }
  }
`;

Shopify CLI

Common Commands

# Create new app
shopify app init

# Start development server
shopify app dev

# Deploy app
shopify app deploy

# Create extension
shopify app generate extension

# Create theme
shopify theme init

# Serve theme locally
shopify theme dev --store=your-store.myshopify.com

# Push theme
shopify theme push

# Pull theme
shopify theme pull

Testing

Test Stores

1. Create Partner account: https://partners.shopify.com
2. Create development store
3. Install your app
4. Test features

Test Data

// Create test product
const product = await shopify.rest.Product.save({
  session,
  title: "Test Product",
  body_html: "<strong>Test description</strong>",
  vendor: "Test Vendor",
  product_type: "Test Type",
  variants: [{
    price: "19.99",
    sku: "TEST-001"
  }]
});

// Create test order
const order = await shopify.rest.Order.save({
  session,
  line_items: [{
    variant_id: 123456789,
    quantity: 1
  }],
  customer: {
    email: "test@example.com"
  }
});

Security Best Practices

1. API Keys:

   • Store in environment variables
   • Never commit to version control
   • Use separate keys per environment
   • Rotate if compromised

2. Webhooks:

   • ALWAYS verify HMAC signatures
   • Use HTTPS endpoints only
   • Return 200 immediately
   • Process async

3. Access Scopes:

   • Request minimal scopes
   • Document why each scope is needed
   • Review periodically

4. Rate Limits:

   • Respect API rate limits
   • Implement exponential backoff
   • Monitor API usage

Common Errors

API Authentication

• Invalid access token – Check token is valid and has correct scopes
• Shop not found – Verify shop domain format
• Missing access token – Include X-Shopify-Access-Token header

GraphQL Errors

• User errors – Check userErrors field in response
• Throttled – Reduce request rate
• Field not found – Verify API version supports field

Webhook Issues

• Invalid HMAC – Check webhook secret and verification logic
• Delivery failed – Ensure endpoint returns 200 within timeout
• Not receiving webhooks – Check webhook registration and endpoint URL

Resources

• Dashboard: https://partners.shopify.com
• Documentation: https://shopify.dev
• GraphiQL Admin: https://shopify.dev/docs/apps/tools/graphiql-admin-api
• Community: https://community.shopify.com
• Status: https://www.shopifystatus.com

Documentation Quick Reference

Need to find something specific?

# Search all docs
grep -r "search term" .claude/skills/shopify/docs/

# Find specific topics
ls .claude/skills/shopify/docs/shopify/

# Read specific guide
cat .claude/skills/shopify/docs/shopify/webhooks.md

Common doc files:

• api-admin-graphql.md – GraphQL Admin API
• api-storefront.md – Storefront API
• authentication.md – OAuth and auth flows
• webhooks.md – Webhook handling
• apps.md – App development
• themes.md – Theme development
• liquid.md – Liquid reference
• hydrogen.md – Headless commerce
• checkout.md – Checkout customization
• functions.md – Shopify Functions
• cli.md – CLI commands