Agent Skills: Shopify Development

Shopify Development

Comprehensive guide for building on Shopify platform: apps, extensions, themes, and API integrations.

Platform Overview

Core Components:

• Shopify CLI - Development workflow tool
• GraphQL Admin API - Primary API for data operations (recommended)
• REST Admin API - Legacy API (maintenance mode)
• Polaris UI - Design system for consistent interfaces
• Liquid - Template language for themes

Extension Points:

• Checkout UI - Customize checkout experience
• Admin UI - Extend admin dashboard
• POS UI - Point of Sale customization
• Customer Account - Post-purchase pages
• Theme App Extensions - Embedded theme functionality

Quick Start

Prerequisites

# Install Shopify CLI
npm install -g @shopify/cli@latest

# Verify installation
shopify version

Create New App

# Initialize app
shopify app init

# Start development server
shopify app dev

# Generate extension
shopify app generate extension --type checkout_ui_extension

# Deploy
shopify app deploy

Theme Development

# Initialize theme
shopify theme init

# Start local preview
shopify theme dev

# Pull from store
shopify theme pull --live

# Push to store
shopify theme push --development

Development Workflow

1. App Development

Setup:

shopify app init
cd my-app

Configure Access Scopes (shopify.app.toml):

[access_scopes]
scopes = "read_products,write_products,read_orders"

Start Development:

shopify app dev  # Starts local server with tunnel

Add Extensions:

shopify app generate extension --type checkout_ui_extension

Deploy:

shopify app deploy  # Builds and uploads to Shopify

2. Extension Development

Available Types:

• Checkout UI - checkout_ui_extension
• Admin Action - admin_action
• Admin Block - admin_block
• POS UI - pos_ui_extension
• Function - function (discounts, payment, delivery, validation)

Workflow:

shopify app generate extension
# Select type, configure
shopify app dev  # Test locally
shopify app deploy  # Publish

3. Theme Development

Setup:

shopify theme init
# Choose Dawn (reference theme) or start fresh

Local Development:

shopify theme dev
# Preview at localhost:9292
# Auto-syncs to development theme

Deployment:

shopify theme push --development  # Push to dev theme
shopify theme publish --theme=123  # Set as live

When to Build What

Build an App When:

• Integrating external services
• Adding functionality across multiple stores
• Building merchant-facing admin tools
• Managing store data programmatically
• Implementing complex business logic
• Charging for functionality

Build an Extension When:

• Customizing checkout flow
• Adding fields/features to admin pages
• Creating POS actions for retail
• Implementing discount/payment/shipping rules
• Extending customer account pages

Build a Theme When:

• Creating custom storefront design
• Building unique shopping experiences
• Customizing product/collection pages
• Implementing brand-specific layouts
• Modifying homepage/content pages

Combination Approach:

App + Theme Extension:

• App handles backend logic and data
• Theme extension provides storefront UI
• Example: Product reviews, wishlists, size guides

Essential Patterns

GraphQL Product Query

query GetProducts($first: Int!) {
  products(first: $first) {
    edges {
      node {
        id
        title
        handle
        variants(first: 5) {
          edges {
            node {
              id
              price
              inventoryQuantity
            }
          }
        }
      }
    }
    pageInfo {
      hasNextPage
      endCursor
    }
  }
}

Checkout Extension (React)

import { reactExtension, BlockStack, TextField, Checkbox } from '@shopify/ui-extensions-react/checkout';

export default reactExtension('purchase.checkout.block.render', () => <Extension />);

function Extension() {
  const [message, setMessage] = useState('');

  return (
    <BlockStack>
      <TextField label="Gift Message" value={message} onChange={setMessage} />
    </BlockStack>
  );
}

Liquid Product Display

{% for product in collection.products %}
  <div class="product-card">
    <img src="{{ product.featured_image | img_url: 'medium' }}" alt="{{ product.title }}">
    <h3>{{ product.title }}</h3>
    <p>{{ product.price | money }}</p>
    <a href="{{ product.url }}">View Details</a>
  </div>
{% endfor %}

Best Practices

API Usage:

• Prefer GraphQL over REST for new development
• Request only needed fields to reduce costs
• Implement pagination for large datasets
• Use bulk operations for batch processing
• Respect rate limits (cost-based for GraphQL)

Security:

• Store API credentials in environment variables
• Verify webhook signatures
• Use OAuth for public apps
• Request minimal access scopes
• Implement session tokens for embedded apps

Performance:

• Cache API responses when appropriate
• Optimize images in themes
• Minimize Liquid logic complexity
• Use async loading for extensions
• Monitor query costs in GraphQL

Testing:

• Use development stores for testing
• Test across different store plans
• Verify mobile responsiveness
• Check accessibility (keyboard, screen readers)
• Validate GDPR compliance

Reference Documentation

Detailed guides for advanced topics:

• App Development - OAuth, APIs, webhooks, billing
• Extensions - Checkout, Admin, POS, Functions
• Themes - Liquid, sections, deployment

Scripts

shopify_init.py - Initialize Shopify projects interactively

python scripts/shopify_init.py

Troubleshooting

Rate Limit Errors:

• Monitor X-Shopify-Shop-Api-Call-Limit header
• Implement exponential backoff
• Use bulk operations for large datasets

Authentication Failures:

• Verify access token validity
• Check required scopes granted
• Ensure OAuth flow completed

Extension Not Appearing:

• Verify extension target correct
• Check extension published
• Ensure app installed on store

Webhook Not Receiving:

• Verify webhook URL accessible
• Check signature validation
• Review logs in Partner Dashboard

Resources

Official Documentation:

• Shopify Docs: https://shopify.dev/docs
• GraphQL API: https://shopify.dev/docs/api/admin-graphql
• Shopify CLI: https://shopify.dev/docs/api/shopify-cli
• Polaris: https://polaris.shopify.com

Tools:

• GraphiQL Explorer (Admin → Settings → Apps → Develop apps)
• Partner Dashboard (app management)
• Development stores (free testing)

API Versioning:

• Quarterly releases (YYYY-MM format)
• Current: 2025-01
• 12-month support per version
• Test before version updates

Note: This skill covers Shopify platform as of January 2025. Refer to official documentation for latest updates.