This commit adds support for request cancellation and tracking of
in-flight requests in the MCP protocol implementation. The key
architectural changes are:
1. Request Lifecycle Management:
- Added _in_flight dictionary to BaseSession to track active requests
- Requests are tracked from receipt until completion/cancellation
- Added proper cleanup via on_complete callback
2. Cancellation Support:
- Added CancelledNotification handling in _receive_loop
- Implemented cancel() method in RequestResponder
- Uses anyio.CancelScope for robust cancellation
- Sends error response on cancellation
3. Request Context:
- Added request_ctx ContextVar for request context
- Ensures proper cleanup after request handling
- Maintains request state throughout lifecycle
4. Error Handling:
- Improved error propagation for cancelled requests
- Added proper cleanup of cancelled requests
- Maintains consistency of in-flight tracking
This change enables clients to cancel long-running requests and
servers to properly clean up resources when requests are cancelled.
Github-Issue:#88
## Goal
Support running an MCP server in the same process as the client, while preserving MCP abstractions.
## Details
1. **(core change)** Adds a new `memory` transport module that enables in-process client-server communication.
This includes:
- `create_client_server_memory_streams()` to create bidirectional memory streams
- `create_connected_server_and_client_session()` to establish an in-process client-server connection
3. (minor) Enhances error handling and timeout support:
- Adds configurable read timeouts to sessions via `read_timeout_seconds` parameter
- Improves exception handling in the server with a new `raise_exceptions` flag to control whether errors are returned to clients or raised directly
- Ensures proper cleanup of request context tokens in error cases
4. (minor) Makes server improvements:
- Adds built-in ping handler support
