diff --git a/.github/workflows/php.yml b/.github/workflows/php.yml
index b41f359..85c41d7 100644
--- a/.github/workflows/php.yml
+++ b/.github/workflows/php.yml
@@ -52,5 +52,8 @@ jobs:
 
       - run: composer install
 
+      - name: Install subversion
+        run: sudo apt-get update && sudo apt-get install -y subversion
+
       - run: bin/install-wp-tests.sh test root root-password 127.0.0.1:${{ job.services.mysql.ports['3306'] }}
       - run: ./vendor/bin/phpunit
diff --git a/CLAUDE.md b/CLAUDE.md
new file mode 100644
index 0000000..2307271
--- /dev/null
+++ b/CLAUDE.md
@@ -0,0 +1,166 @@
+# CLAUDE.md
+
+This document provides guidance for Claude Code (claude.ai/code) **and developers** working with code in this repository.
+
+---
+
+## Project Overview
+
+This is a WordPress plugin that integrates with the ColorMe Shop (カラーミーショップ) API to display product information and generate product pages within WordPress.  
+It uses OAuth2 authentication and provides WordPress shortcodes for embedding product details.
+
+---
+
+## Development Commands
+
+### Setup
+
+```bash
+# Copy environment file and start Docker containers
+cp wp.env.sample wp.env
+docker-compose up -d
+
+# Install PHP dependencies via Composer
+docker-compose run --rm composer install
+```
+
+> After setup, activate the plugin from the WordPress admin dashboard.
+
+---
+
+### Testing
+
+```bash
+# Run unit tests
+./tests/run.sh
+
+# Run tests using Docker (WordPress environment)
+docker-compose run --rm wordpress bash -c   "cd /var/www/html/wp-content/plugins/colormeshop-wp-plugin && ./vendor/bin/phpunit"
+```
+
+- Tests use the WordPress test framework and VCR for recording/replaying HTTP requests
+- VCR fixtures are stored in `tests/fixtures/`
+- New API interactions can be recorded by switching VCR to record mode
+- Coverage reports exclude generated Swagger code
+
+---
+
+### Code Quality
+
+```bash
+# Check coding standards (WordPress Coding Standards)
+docker-compose run composer vendor/bin/phpcs --standard=ruleset.xml
+
+# Auto-fix formatting issues
+docker-compose run composer vendor/bin/phpcbf --standard=ruleset.xml
+```
+
+> Note: This plugin follows WordPress coding standards and naming conventions.  
+> Claude should preserve these when suggesting code changes.
+
+---
+
+### Build and Deployment
+
+```bash
+# Generate API client from ColorMe Shop API (Swagger/OpenAPI)
+make generate_api_client
+
+# Build plugin zip for distribution (output: ./dist/colormeshop-wp-plugin.zip)
+make
+
+# Update autoload classmap after adding new classes
+docker-compose run --rm composer dump-autoload
+```
+
+---
+
+## Architecture
+
+### Core Components
+
+- **Plugin**: Main orchestrator that registers hooks, shortcodes, and DI container
+- **Admin**: WordPress admin UI for plugin settings (OAuth credentials, page IDs)
+- **Models**: Internal models for plugin settings and sitemap generation
+- **API Layer**: Wrapper around Swagger-generated client for ColorMe Shop API
+- **Shortcodes**: Functions to embed product data, images, cart buttons via shortcodes
+
+---
+
+### Key File Structure
+
+| Path                         | Purpose                                    |
+|-----------------------------|--------------------------------------------|
+| `src/class-plugin.php`      | Plugin bootstrap and DI setup              |
+| `src/class-admin.php`       | Admin UI and setting page                  |
+| `src/Swagger/`              | Auto-generated ColorMe API client          |
+| `src/shortcodes/`           | Shortcode definitions                      |
+| `src/models/`               | Data models and logic                      |
+| `templates/`                | PHP templates used in rendering            |
+
+> Note: Filenames like `class-plugin.php` follow WordPress conventions — do not rename them.
+
+---
+
+### Dependency Injection (DI)
+
+- The plugin uses [Pimple](https://pimple.symfony.com/) as a DI container.
+- Key service bindings:
+  - `oauth2_client`: OAuth2 client instance
+  - `api.product_api`: Product API abstraction
+  - `model.setting`: WordPress options access wrapper
+  - `swagger.configuration`: Swagger client configuration (access token injected)
+
+---
+
+### Database Integration
+
+- Plugin settings are stored using the WordPress Options API under the key:
+
+```
+colorme_wp_settings
+```
+
+---
+
+### API Integration
+
+- Uses Swagger client generated from ColorMe Shop API v1
+- Authenticated via OAuth2 access token (user-provided)
+- Abstraction layer wraps raw API client for safer access
+- VCR (PHP-VCR) used to record HTTP interactions during tests
+
+---
+
+### WordPress Integration
+
+- Custom rewrite rules for product pages and sitemap XML
+- Uses hooks for title filtering and template redirection
+- Supports device detection for rendering mobile-specific views
+- Template override support via standard WordPress theme hierarchy
+
+---
+
+## Claude Usage Tips
+
+- When modifying shortcodes, ensure arguments are processed using `shortcode_atts()`
+- Always retrieve settings via the `model.setting` service rather than accessing options directly
+- When adding templates, place them in the `templates/` directory and reference with `include()`
+- When working on OAuth2 logic, ensure secure token storage using WP options and proper sanitization
+- Avoid modifying files in `src/Swagger/` directly — these are auto-generated
+
+---
+
+## Appendix
+
+### External Dependencies
+
+- WordPress ≥ 5.0
+- Composer (for dependency management)
+- Docker (for development environment)
+
+---
+
+## License
+
+See `LICENSE` file in the root of this repository.