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SEP-1686: Tasks (#1645)

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Max Isbey 2025-11-28 18:51:58 +00:00 • committed by GitHub
commit c92bb2f7ff
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1 changed files with 14230 additions and 120 deletions
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57
src/mcp/server/lowlevel/server.py
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@ -67,6 +67,7 @@ messages from the client.
from __future__ import annotations as _annotations
import base64
import contextvars
import json
import logging
@ -82,6 +83,8 @@ from pydantic import AnyUrl
from typing_extensions import TypeVar
import mcp.types as types
from mcp.server.experimental.request_context import Experimental
from mcp.server.lowlevel.experimental import ExperimentalHandlers
from mcp.server.lowlevel.func_inspection import create_call_wrapper
from mcp.server.lowlevel.helper_types import ReadResourceContents
from mcp.server.models import InitializationOptions
@ -155,6 +158,7 @@ class Server(Generic[LifespanResultT, RequestT]):
}
self.notification_handlers: dict[type, Callable[..., Awaitable[None]]] = {}
self._tool_cache: dict[str, types.Tool] = {}
self._experimental_handlers: ExperimentalHandlers | None = None
logger.debug("Initializing server %r", name)
def create_initialization_options(
@ -220,7 +224,7 @@ class Server(Generic[LifespanResultT, RequestT]):
if types.CompleteRequest in self.request_handlers:
completions_capability = types.CompletionsCapability()
return types.ServerCapabilities(
capabilities = types.ServerCapabilities(
prompts=prompts_capability,
resources=resources_capability,
tools=tools_capability,
@ -228,6 +232,9 @@ class Server(Generic[LifespanResultT, RequestT]):
experimental=experimental_capabilities,
completions=completions_capability,
)
if self._experimental_handlers:
self._experimental_handlers.update_capabilities(capabilities)
return capabilities
@property
def request_context(
@ -236,6 +243,18 @@ class Server(Generic[LifespanResultT, RequestT]):
"""If called outside of a request context, this will raise a LookupError."""
return request_ctx.get()
@property
def experimental(self) -> ExperimentalHandlers:
"""Experimental APIs for tasks and other features.
WARNING: These APIs are experimental and may change without notice.
"""
# We create this inline so we only add these capabilities _if_ they're actually used
if self._experimental_handlers is None:
self._experimental_handlers = ExperimentalHandlers(self, self.request_handlers, self.notification_handlers)
return self._experimental_handlers
def list_prompts(self):
def decorator(
func: Callable[[], Awaitable[list[types.Prompt]]]
@ -328,8 +347,6 @@ class Server(Generic[LifespanResultT, RequestT]):
mimeType=mime_type or "text/plain",
)
case bytes() as data: # pragma: no cover
import base64
return types.BlobResourceContents(
uri=req.params.uri,
blob=base64.b64encode(data).decode(),
@ -483,7 +500,13 @@ class Server(Generic[LifespanResultT, RequestT]):
def decorator(
func: Callable[
...,
Awaitable[UnstructuredContent | StructuredContent | CombinationContent | types.CallToolResult],
Awaitable[
UnstructuredContent
| StructuredContent
| CombinationContent
| types.CallToolResult
| types.CreateTaskResult
],
],
):
logger.debug("Registering handler for CallToolRequest")
@ -509,6 +532,9 @@ class Server(Generic[LifespanResultT, RequestT]):
maybe_structured_content: StructuredContent | None
if isinstance(results, types.CallToolResult):
return types.ServerResult(results)
elif isinstance(results, types.CreateTaskResult):
# Task-augmented execution returns task info instead of result
return types.ServerResult(results)
elif isinstance(results, tuple) and len(results) == 2:
# tool returned both structured and unstructured content
unstructured_content, maybe_structured_content = cast(CombinationContent, results)
@ -627,6 +653,12 @@ class Server(Generic[LifespanResultT, RequestT]):
)
)
# Configure task support for this session if enabled
task_support = self._experimental_handlers.task_support if self._experimental_handlers else None
if task_support is not None:
task_support.configure_session(session)
await stack.enter_async_context(task_support.run())
async with anyio.create_task_group() as tg:
async for message in session.incoming_messages:
logger.debug("Received message: %s", message)
@ -669,13 +701,14 @@ class Server(Generic[LifespanResultT, RequestT]):
async def _handle_request(
self,
message: RequestResponder[types.ClientRequest, types.ServerResult],
req: Any,
req: types.ClientRequestType,
session: ServerSession,
lifespan_context: LifespanResultT,
raise_exceptions: bool,
):
logger.info("Processing request of type %s", type(req).__name__)
if handler := self.request_handlers.get(type(req)): # type: ignore
if handler := self.request_handlers.get(type(req)):
logger.debug("Dispatching request of type %s", type(req).__name__)
token = None
@ -689,12 +722,24 @@ class Server(Generic[LifespanResultT, RequestT]):
# Set our global state that can be retrieved via
# app.get_request_context()
client_capabilities = session.client_params.capabilities if session.client_params else None
task_support = self._experimental_handlers.task_support if self._experimental_handlers else None
# Get task metadata from request params if present
task_metadata = None
if hasattr(req, "params") and req.params is not None:
task_metadata = getattr(req.params, "task", None)
token = request_ctx.set(
RequestContext(
message.request_id,
message.request_meta,
session,
lifespan_context,
Experimental(
task_metadata=task_metadata,
_client_capabilities=client_capabilities,
_session=session,
_task_support=task_support,
),
request=request_data,
)
)