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:

Search for specific topics:

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

Read specific documentation:

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

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

Create Partner account: https://partners.shopify.com
Create development store
Install your app
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: "[email protected]"
  }
});

Security Best Practices

API Keys:
- Store in environment variables
- Never commit to version control
- Use separate keys per environment
- Rotate if compromised
Webhooks:
- ALWAYS verify HMAC signatures
- Use HTTPS endpoints only
- Return 200 immediately
- Process async
Access Scopes:
- Request minimal scopes
- Document why each scope is needed
- Review periodically
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

shopify

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