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base repository: modelcontextprotocol/python-sdk
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head repository: modelcontextprotocol/python-sdk
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compare: v2-design-sketches
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  • 8 commits
  • 23 files changed
  • 2 contributors

Commits on Jan 24, 2026

  1. wip: add v2 lowlevel server design sketch 

    Initial sketch exploring a simplified lowlevel server API:
- Method-string based handler registration
- Context object for bidirectional communication
- Separate request/notification handlers
- Transport abstraction with GET stream handler

Also excludes v2_scratch and scratch folders from linting.

This is exploratory design work for SDK v2.
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    maxisbey committed Jan 24, 2026
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  2. wip: refine v2 lowlevel server types and handlers 

    - Add type-safe method registration with Literal unions (RequestMethod,
  ClientNotificationMethod, ServerNotificationMethod)
- Switch notification params from TypedDicts to BaseModels for
  consistency and proxy support
- Add Context dataclass with send_notification and send_request for
  bidirectional communication
- Result types inherit from JSONRPCResponse with id from request
- Clean up handler examples to use new types

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    maxisbey and claude committed Jan 24, 2026
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  3. wip: reorganize v2 sketch into transport subpackage 

    - Extract Transport protocol, Context, and StreamableHTTPTransport
  into v2_scratch/transport/ subpackage
- Rename JSONRPCResponse -> JSONRPCResultResponse for clarity
- Add JSONRPCErrorResponse with structured ErrorData
- Make JSONRPCResponse a type alias (Result | Error) per spec
- Remove v2_scratch from ruff exclude (enable linting)
- Add py.typed marker and __init__.py files

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  4. wip: checkpoint - mcp_v2 types with generic bases and TypeAdapter 

    - Add json_rpc.py with generic bases (RequestBase, NotificationBase,
  ResultResponseBase) for typed message subclasses
- Add JSONRPCMessageAdapter for automatic message type discrimination
- Update types.py to use generic bases for typed requests/notifications
- Add parametrized tests for TypeAdapter discrimination
- Reorganize v2_scratch -> src/mcp_v2

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  5. wip: add extra="allow" to all protocol types via base classes 

    - Add model_config with extra="allow" to JSONRPCBase and ErrorData
- Create MCPModel base class with extra="allow" for MCP domain types
- Update inheritance: params inherit from RequestParams, results from Result
- Add snake_case aliases for camelCase fields (protocol_version, etc.)
- Add Meta, Icon, Annotations, ToolAnnotations, ToolExecution, JsonSchema types
- Expand Tool model with all spec fields

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  6. wip: restructure mcp_v2 types into separate modules 

    - Split types.py into base.py, common.py, content.py, initialize.py,
  tools.py, and resources.py
- Fix transport imports to use specific module paths
- Update Context.send_notification to take method as separate param
- Use X | None instead of Optional[X] (with PyCharm noinspection comments)
- All ruff and pyright checks pass

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  7. checkpoint

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  8. wip: add Starlette-style lifespan to v2 LowLevelServer 

    - Lifespan is now an async context manager that receives the server
- Lifespan runs ONCE for the server lifetime, not per-session
- Add separate session_lifespan for per-session state
- Runner pattern: run() enters lifespan, handle_session() reuses it
- Matches Starlette/FastAPI lifespan semantics

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