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https://github.com/PrefectHQ/fastmcp.git
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bb4894d215* Add fastmcp-client workspace package * Fix client package static checks * Document client-only package * Harden fastmcp-client package split * Preserve forwarded headers in full package * Switch to fastmcp-slim package * Fix fastmcp-slim release edges * Match pydantic-style slim layout * Polish fastmcp-slim packaging
128 lines
4.7 KiB
Python
128 lines
4.7 KiB
Python
from typing import TypeAlias
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import mcp.types
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from mcp.client.session import MessageHandlerFnT
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from mcp.shared.session import RequestResponder
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Message: TypeAlias = (
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RequestResponder[mcp.types.ServerRequest, mcp.types.ClientResult]
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| mcp.types.ServerNotification
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| Exception
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)
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MessageHandlerT: TypeAlias = MessageHandlerFnT
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class MessageHandler:
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"""
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This class is used to handle MCP messages sent to the client. It is used to handle all messages,
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requests, notifications, and exceptions. Users can override any of the hooks
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"""
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async def __call__(
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self,
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message: RequestResponder[mcp.types.ServerRequest, mcp.types.ClientResult]
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| mcp.types.ServerNotification
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| Exception,
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) -> None:
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return await self.dispatch(message)
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async def dispatch(self, message: Message) -> None:
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# handle all messages
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await self.on_message(message)
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match message:
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# requests
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case RequestResponder():
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# handle all requests
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# TODO(ty): remove when ty supports match statement narrowing
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await self.on_request(message) # type: ignore[arg-type] # ty:ignore[invalid-argument-type]
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# handle specific requests
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# TODO(ty): remove type ignores when ty supports match statement narrowing
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match message.request.root: # type: ignore[union-attr] # ty:ignore[unresolved-attribute]
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case mcp.types.PingRequest():
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await self.on_ping(message.request.root) # type: ignore[union-attr] # ty:ignore[unresolved-attribute]
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case mcp.types.ListRootsRequest():
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await self.on_list_roots(message.request.root) # type: ignore[union-attr] # ty:ignore[unresolved-attribute]
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case mcp.types.CreateMessageRequest():
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await self.on_create_message(message.request.root) # type: ignore[union-attr] # ty:ignore[unresolved-attribute]
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# notifications
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case mcp.types.ServerNotification():
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# handle all notifications
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await self.on_notification(message)
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# handle specific notifications
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match message.root:
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case mcp.types.CancelledNotification():
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await self.on_cancelled(message.root)
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case mcp.types.ProgressNotification():
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await self.on_progress(message.root)
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case mcp.types.LoggingMessageNotification():
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await self.on_logging_message(message.root)
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case mcp.types.ToolListChangedNotification():
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await self.on_tool_list_changed(message.root)
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case mcp.types.ResourceListChangedNotification():
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await self.on_resource_list_changed(message.root)
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case mcp.types.PromptListChangedNotification():
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await self.on_prompt_list_changed(message.root)
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case mcp.types.ResourceUpdatedNotification():
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await self.on_resource_updated(message.root)
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case Exception():
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await self.on_exception(message)
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async def on_message(self, message: Message) -> None:
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pass
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async def on_request(
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self, message: RequestResponder[mcp.types.ServerRequest, mcp.types.ClientResult]
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) -> None:
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pass
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async def on_ping(self, message: mcp.types.PingRequest) -> None:
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pass
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async def on_list_roots(self, message: mcp.types.ListRootsRequest) -> None:
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pass
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async def on_create_message(self, message: mcp.types.CreateMessageRequest) -> None:
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pass
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async def on_notification(self, message: mcp.types.ServerNotification) -> None:
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pass
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async def on_exception(self, message: Exception) -> None:
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pass
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async def on_progress(self, message: mcp.types.ProgressNotification) -> None:
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pass
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async def on_logging_message(
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self, message: mcp.types.LoggingMessageNotification
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) -> None:
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pass
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async def on_tool_list_changed(
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self, message: mcp.types.ToolListChangedNotification
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) -> None:
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pass
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async def on_resource_list_changed(
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self, message: mcp.types.ResourceListChangedNotification
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) -> None:
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pass
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async def on_prompt_list_changed(
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self, message: mcp.types.PromptListChangedNotification
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) -> None:
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pass
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async def on_resource_updated(
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self, message: mcp.types.ResourceUpdatedNotification
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) -> None:
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pass
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async def on_cancelled(self, message: mcp.types.CancelledNotification) -> None:
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pass
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