Asynchronous Support for Bedrock Session Management Service

Overview

This PR adds asynchronous support for Bedrock Session Management Service in the LangGraph checkpoint system, enabling non-blocking I/O operations.

Key Components

AsyncBedrockAgentRuntimeSessionClient

• Provides asynchronous wrappers around boto3 Bedrock Session Management Service API calls
• Uses executor-based approach for non-blocking operations

AsyncBedrockSessionSaver

• Implements async versions of all checkpoint operations (aget, aput, aput_writes, alist)
• Maintains compatibility with the synchronous implementation

Implementation Details

• Uses standard Python async/await patterns
• Preserves error handling and functionality of synchronous version

Benefits

• Enables calling LangGraph workflows asynchronously via ainvoke and astream methods
• Improves performance for I/O-bound applications
• Maintains full compatibility with existing checkpoint system

Testing

• Added comprehensive unit tests for async functionality
• Implemented integration tests to verify real-world behavior with Bedrock Session Management Service