# Technology Stack

## Runtime & Dependencies

- **Node.js**: >=16.0.0 (specified in package.json engines)
- **Core Dependencies**:
  - `@shopify/shopify-api`: ^7.7.0 - Shopify GraphQL API client
  - `dotenv`: ^16.3.1 - Environment variable management
  - `node-fetch`: ^3.3.2 - HTTP client for API requests
- **Development Dependencies**:
  - `jest`: ^29.7.0 - Testing framework

## Architecture Patterns

- **Service Layer Architecture**: Separation of concerns with dedicated services
- **Configuration Management**: Centralized environment-based configuration
- **Error Handling**: Comprehensive retry logic with exponential backoff
- **Logging Strategy**: Dual output (console + Progress.md file)

## API Integration

- **Shopify GraphQL Admin API**: Version 2024-01
- **Authentication**: Private App access tokens
- **Rate Limiting**: Built-in handling with automatic retries
- **Bulk Operations**: Uses `productVariantsBulkUpdate` mutation

## Common Commands

### Development

```bash
npm install                    # Install dependencies
npm start                     # Run with default settings
npm run update                # Explicit update mode
npm run rollback              # Rollback mode
npm run debug-tags            # Debug tag analysis
npm test                      # Run test suite
```

### Environment Setup

```bash
copy .env.example .env        # Create environment file (Windows)
cp .env.example .env          # Create environment file (Unix)
```

### Testing & Debugging

```bash
npm run debug-tags            # Analyze store tags before running
npm test                      # Run Jest test suite
```

## Environment Variables

Required variables (see .env.example):

- `SHOPIFY_SHOP_DOMAIN`: Store domain
- `SHOPIFY_ACCESS_TOKEN`: Admin API token
- `TARGET_TAG`: Product tag filter
- `PRICE_ADJUSTMENT_PERCENTAGE`: Adjustment percentage
- `OPERATION_MODE`: "update" or "rollback"