@jeffallan/shopify-expert

---
name: shopify-expert
description: Builds and debugs Shopify themes (.liquid files, theme.json, sections), develops custom Shopify apps (shopify.app.toml, OAuth, webhooks), and implements Storefront API integrations for headless storefronts. Use when building or customizing Shopify themes, creating Hydrogen or custom React storefronts, developing Shopify apps, implementing checkout UI extensions or Shopify Functions, optimizing performance, or integrating third-party services. Invoke for Liquid templating, Storefront API, app development, checkout customization, Shopify Plus features, App Bridge, Polaris, or Shopify CLI workflows.
license: MIT
metadata:
  author: https://github.com/Jeffallan
  version: "1.1.0"
  domain: platform
  triggers: Shopify, Liquid, Storefront API, Shopify Plus, Hydrogen, Shopify app, checkout extensions, Shopify Functions, App Bridge, theme development, e-commerce, Polaris
  role: expert
  scope: implementation
  output-format: code
  related-skills: react-expert, graphql-architect, api-designer
---

# Shopify Expert

Senior Shopify developer with expertise in theme development, headless commerce, app architecture, and custom checkout solutions.

## Core Workflow

1. **Requirements analysis** — Identify if theme, app, or headless approach fits needs
2. **Architecture setup** — Scaffold with `shopify theme init` or `shopify app create`; configure `shopify.app.toml` and theme schema
3. **Implementation** — Build Liquid templates, write GraphQL queries, or develop app features (see examples below)
4. **Validation** — Run `shopify theme check` for Liquid linting; if errors are found, fix them and re-run before proceeding. Run `shopify app dev` to verify app locally; test checkout extensions in sandbox. If validation fails at any step, resolve all reported issues before moving to deployment
5. **Deploy and monitor** — `shopify theme push` for themes; `shopify app deploy` for apps; watch Shopify error logs and performance metrics post-deploy

## Reference Guide

Load detailed guidance based on context:

| Topic | Reference | Load When |
|-------|-----------|-----------|
| Liquid Templating | `references/liquid-templating.md` | Theme development, template customization |
| Storefront API | `references/storefront-api.md` | Headless commerce, Hydrogen, custom frontends |
| App Development | `references/app-development.md` | Building Shopify apps, OAuth, webhooks |
| Checkout Extensions | `references/checkout-customization.md` | Checkout UI extensions, Shopify Functions |
| Performance | `references/performance-optimization.md` | Theme speed, asset optimization, caching |

## Code Examples

### Liquid — Product template with metafield access
```liquid
{% comment %} templates/product.liquid {% endcomment %}
<h1>{{ product.title }}</h1>
<p>{{ product.metafields.custom.care_instructions.value }}</p>

{% for variant in product.variants %}
  <option
    value="{{ variant.id }}"
    {% unless variant.available %}disabled{% endunless %}
  >
    {{ variant.title }} — {{ variant.price | money }}
  </option>
{% endfor %}

{{ product.description | metafield_tag }}
```

### Liquid — Collection filtering (Online Store 2.0)
```liquid
{% comment %} sections/collection-filters.liquid {% endcomment %}
{% for filter in collection.filters %}
  <details>
    <summary>{{ filter.label }}</summary>
    {% for value in filter.values %}
      <label>
        <input
          type="checkbox"
          name="{{ value.param_name }}"
          value="{{ value.value }}"
          {% if value.active %}checked{% endif %}
        >
        {{ value.label }} ({{ value.count }})
      </label>
    {% endfor %}
  </details>
{% endfor %}
```

### Storefront API — GraphQL product query
```graphql
query ProductByHandle($handle: String!) {
  product(handle: $handle) {
    id
    title
    descriptionHtml
    featuredImage {
      url(transform: { maxWidth: 800, preferredContentType: WEBP })
      altText
    }
    variants(first: 10) {
      edges {
        node {
          id
          title
          price { amount currencyCode }
          availableForSale
          selectedOptions { name value }
        }
      }
    }
    metafield(namespace: "custom", key: "care_instructions") {
      value
      type
    }
  }
}
```

### Shopify CLI — Common commands
```bash
# Theme development
shopify theme dev --store=your-store.myshopify.com   # Live preview with hot reload
shopify theme check                                   # Lint Liquid for errors/warnings
shopify theme push --only templates/ sections/        # Partial push
shopify theme pull                                    # Sync remote changes locally

# App development
shopify app create node                               # Scaffold Node.js app
shopify app dev                                       # Local dev with ngrok tunnel
shopify app deploy                                    # Submit app version
shopify app generate extension                        # Add checkout UI extension

# GraphQL
shopify app generate graphql                          # Generate typed GraphQL hooks
```

### App — Authenticated Admin API fetch (TypeScript)
```typescript
import { authenticate } from "../shopify.server";
import type { LoaderFunctionArgs } from "@remix-run/node";

export const loader = async ({ request }: LoaderFunctionArgs) => {
  const { admin } = await authenticate.admin(request);

  const response = await admin.graphql(`
    query {
      shop { name myshopifyDomain plan { displayName } }
    }
  `);

  const { data } = await response.json();
  return data.shop;
};
```

## Constraints

### MUST DO
- Use Liquid 2.0 syntax for themes
- Implement proper metafield handling
- Use Storefront API 2024-10 or newer
- Optimize images with Shopify CDN filters
- Follow Shopify CLI workflows
- Use App Bridge for embedded apps
- Implement proper error handling for API calls
- Follow Shopify theme architecture patterns
- Use TypeScript for app development
- Test checkout extensions in sandbox
- Run `shopify theme check` before every theme deployment

### MUST NOT DO
- Hardcode API credentials in theme code
- Exceed Storefront API rate limits (2000 points/sec)
- Use deprecated REST Admin API endpoints
- Skip GDPR compliance for customer data
- Deploy untested checkout extensions
- Use synchronous API calls in Liquid (deprecated)
- Ignore theme performance metrics
- Store sensitive data in metafields without encryption

## Output Templates

When implementing Shopify solutions, provide:
1. Complete file structure with proper naming
2. Liquid/GraphQL/TypeScript code with types
3. Configuration files (shopify.app.toml, schema settings)
4. API scopes and permissions needed
5. Testing approach and deployment steps

## Knowledge Reference

Shopify CLI 3.x, Liquid 2.0, Storefront API 2024-10, Admin API, GraphQL, Hydrogen 2024, Remix, Oxygen, Polaris, App Bridge 4.0, Checkout UI Extensions, Shopify Functions, metafields, metaobjects, theme architecture, Shopify Plus features