Update CLAUDE.md to reflect SDK enhancements and testing instructions

- Updated project overview to include new features in SOLAPI PHP SDK version 5.1.0, including PSR-18 HTTP client requirements.
- Added detailed testing commands for unit, end-to-end, and coverage tests.
- Revised architecture section to reflect changes in the HTTP client implementation.
- Enhanced documentation on E2E test environment variables and SSL verification settings.

Author: Palbahngmiyine

CLAUDE.md

@@ -4,15 +4,40 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 ## Project Overview
 
-SOLAPI PHP SDK - A zero-dependency messaging SDK for Korean telecommunications (SMS, LMS, MMS, Kakao Alimtalk, Voice, Fax). Version 5.0.6, requires PHP 7.1+ with curl and json extensions.
+SOLAPI PHP SDK - A messaging SDK for Korean telecommunications (SMS, LMS, MMS, Kakao Alimtalk, Kakao BMS, Voice, Fax). Version 5.1.0, requires PHP 7.1+ with json extension and `allow_url_fopen` enabled (or a custom PSR-18 HTTP client).
+
+**Dependencies:** PSR HTTP interfaces (psr/http-client, psr/http-message) + nyholm/psr7
 
 ## Commands
 
 ```bash
-# Install dependencies (none required, autoloader only)
+# Install dependencies
 composer install
 
-# There are no local tests - see https://github.com/solapi/solapi-php-examples for usage examples
+# Run all tests
+composer test
+
+# Unit tests only (no API calls required)
+composer test:unit
+
+# E2E tests (requires environment variables - see below)
+composer test:e2e
+
+# Run with coverage report
+composer test:coverage
+
+# Run a single test
+./vendor/bin/phpunit --filter testName
+```
+
+### E2E Test Environment Variables
+
+```bash
+SOLAPI_API_KEY=xxx
+SOLAPI_API_SECRET=xxx
+SOLAPI_KAKAO_PF_ID=xxx
+SOLAPI_SENDER_NUMBER=01012345678
+SOLAPI_RECIPIENT_NUMBER=01087654321
 ```
 
 ## Architecture
@@ -21,19 +46,21 @@ composer install
 
 **Call Flow:**
 ```
-SolapiMessageService → Fetcher (singleton) → Authenticator (static) → CURL → api.solapi.com
+SolapiMessageService → Fetcher (singleton) → Authenticator (static) → HttpClient (stream_context) → api.solapi.com
 ```
 
 **Key Classes:**
 - `SolapiMessageService` - Primary API: send(), uploadFile(), getMessages(), getGroups(), getBalance()
 - `Message` (`Models/Message.php`) - Fluent builder for message construction
-- `Fetcher` (`Libraries/Fetcher.php`) - Singleton HTTP client
+- `Fetcher` (`Libraries/Fetcher.php`) - Singleton HTTP client orchestrator
+- `HttpClient` (`Libraries/HttpClient.php`) - PSR-18 implementation using `stream_context` + `file_get_contents`
 - `Authenticator` (`Libraries/Authenticator.php`) - HMAC-SHA256 auth header generation
 
 **Models Structure:**
 - `Models/Request/` - 7 request DTOs (SendRequest, GetMessagesRequest, etc.)
 - `Models/Response/` - 17 response DTOs (SendResponse, GroupMessageResponse, etc.)
 - `Models/Kakao/` - Kakao message options (pfId, templateId, buttons)
+- `Models/Kakao/Bms/` - Kakao Brand Message Service (14 files, 8 chatBubbleTypes) - see `src/Models/Kakao/Bms/AGENTS.md`
 - `Models/Voice/` - Voice message options
 - `Models/Fax/` - Fax message options
 
@@ -78,7 +105,8 @@ Follow Kent Beck's "Tidy First" principles when making code changes:
 - **Singleton State:** Fetcher singleton retains credentials - don't mix different API keys in the same process
 - **Null Returns:** Many get* methods return `null` on any exception instead of throwing - always check response validity
 - **No Interfaces:** Service/Fetcher lack contracts - mocking requires concrete class extension
-- **SSL Verification:** Disabled in Fetcher (`CURLOPT_SSL_VERIFYPEER = false`)
+- **PSR-18 HTTP Client:** Default HttpClient uses `stream_context` + `file_get_contents`. A custom PSR-18 client can be injected if needed (e.g., for cURL or Guzzle)
+- **SSL Verification:** Enabled by default in HttpClient; can be disabled via constructor options
 
 ## External Resources