Implement robust network reconnection handling for VK Bot

[konard]

Summary

This PR implements robust network error handling and automatic reconnection capabilities for the VK Bot to solve issue #70. The bot now gracefully handles network disconnections, timeouts, and connection recovery scenarios without losing connection to VK.

🐛 Problem Solved

• Issue: Bot does not detect network changes/reconnection, leading to connection loss with VK
• Root cause: No error handling or retry logic for network failures in the original implementation
• Impact: Bot becomes unresponsive during network issues and requires manual restart

✨ Solution Overview

The solution adds a comprehensive network handling layer that:

• Automatically retries failed requests with exponential backoff
• Monitors connection health with background health checks
• Logs detailed information about network issues and recovery
• Handles various error types including timeouts, connection errors, and VK API errors
• Provides connection statistics for monitoring and debugging

🔧 Key Changes

New Components

1. NetworkHandler class (python/network_handler.py)

   • Configurable retry strategy with exponential backoff
   • Background health monitoring thread
   • Connection statistics and status tracking
   • Comprehensive error logging and handling

2. VkNetworkMixin class

   • Mixin to add network resilience to any VK bot class
   • Overrides call_method to use enhanced request handling
   • Automatic session management with retry configuration

Enhanced Existing Components

3. Updated Bot class (python/__main__.py)

   • Now inherits from VkNetworkMixin for automatic network resilience
   • Maintains all existing functionality while adding error handling

4. Enhanced UserBot class (python/userbot.py)

   • Converted to instance-based class with network handling
   • Uses NetworkHandler for all VK API requests
   • Added error logging and exception handling

📊 Features

• Automatic Retry Logic: Configurable number of retries (default: 5) with exponential backoff
• Health Monitoring: Background health checks every 60 seconds (configurable)
• Error Classification: Handles connection errors, timeouts, HTTP errors, and VK API errors differently
• Connection Statistics: Tracks success/failure rates and connection health
• Detailed Logging: Comprehensive logging for debugging network issues
• Graceful Degradation: Bot continues operating even with intermittent connectivity issues

🧪 Testing

Added comprehensive test suite:

• Unit tests for NetworkHandler and VkNetworkMixin (experiments/test_network_resilience.py)
• Integration tests simulating various network failure scenarios
• Example script demonstrating network resilience features (examples/network_resilience_example.py)

🎯 Configuration Options

The NetworkHandler can be configured with:

NetworkHandler(
    max_retries=5,              # Maximum retry attempts
    backoff_factor=0.5,         # Exponential backoff multiplier
    retry_status_codes=(429, 500, 502, 503, 504),  # HTTP codes to retry
    connection_timeout=10,       # Connection timeout in seconds
    read_timeout=30,            # Read timeout in seconds
    health_check_interval=60    # Health check interval in seconds
)

🔍 Implementation Details

The solution uses a mixin pattern to add network resilience without breaking existing functionality:

1. Request Layer: All VK API calls go through NetworkHandler.make_request()
2. Session Management: Uses requests.Session with configured retry adapters
3. Error Recovery: Implements exponential backoff and connection health tracking
4. Background Monitoring: Optional health check thread monitors connectivity
5. Logging: Detailed logging helps with debugging and monitoring

📈 Benefits

• Improved Reliability: Bot stays connected during network issues
• Automatic Recovery: No manual intervention needed for temporary disconnections
• Better Monitoring: Connection statistics help identify patterns
• Minimal Performance Impact: Optimized retry logic and async health checks
• Backward Compatibility: All existing bot functionality preserved

🔗 Related

• Fixes Bot does not detect the network change/reconnection, this leads to connection lost with VK #70 - Bot does not detect network change/reconnection
• Addresses the suggestion to switch to vkwave by implementing robust error handling that can work with any VK library

The implementation maintains compatibility with the existing saya library while adding the network resilience features that would be expected from more modern libraries like vkwave.

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🤖 AI Implementation Notes

This solution was automatically generated by analyzing the issue, researching VK API libraries, and implementing a comprehensive network handling solution that addresses the core problem while maintaining backward compatibility.

🤖 Generated with Claude Code