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Server-side 2026-07-28 stateless support: classifier, driver split, server/discover (#2928)

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Max 2026-06-21 19:34:17 +01:00 • committed by GitHub
commit 2397319a68
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1 changed files with 2256 additions and 1088 deletions
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45
src/mcp/server/streamable_http.py
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@ -28,7 +28,7 @@ from mcp.server.transport_security import TransportSecurityMiddleware, Transport
from mcp.shared._context_streams import ContextReceiveStream, ContextSendStream, create_context_streams
from mcp.shared._stream_protocols import ReadStream, WriteStream
from mcp.shared.message import ServerMessageMetadata, SessionMessage
from mcp.shared.version import SUPPORTED_PROTOCOL_VERSIONS, is_version_at_least
from mcp.shared.version import is_version_at_least
from mcp.types import (
DEFAULT_NEGOTIATED_VERSION,
INTERNAL_ERROR,
@ -248,12 +248,11 @@ class StreamableHTTPServerTransport:
metadata = ServerMessageMetadata(
request_context=request,
protocol_version=protocol_version,
close_sse_stream=close_stream_callback,
close_standalone_sse_stream=close_standalone_stream_callback,
)
else:
metadata = ServerMessageMetadata(request_context=request, protocol_version=protocol_version)
metadata = ServerMessageMetadata(request_context=request)
return SessionMessage(message, metadata=metadata)
@ -507,10 +506,7 @@ class StreamableHTTPServerTransport:
await response(scope, receive, send)
# Process the message after sending the response
metadata = ServerMessageMetadata(
request_context=request,
protocol_version=request.headers.get(MCP_PROTOCOL_VERSION_HEADER, DEFAULT_NEGOTIATED_VERSION),
)
metadata = ServerMessageMetadata(request_context=request)
session_message = SessionMessage(message, metadata=metadata)
await writer.send(session_message)
@ -533,7 +529,7 @@ class StreamableHTTPServerTransport:
if self.is_json_response_enabled:
# Process the message
metadata = ServerMessageMetadata(request_context=request, protocol_version=protocol_version)
metadata = ServerMessageMetadata(request_context=request)
session_message = SessionMessage(message, metadata=metadata)
await writer.send(session_message)
try:
@ -818,11 +814,10 @@ class StreamableHTTPServerTransport:
await response(request.scope, request.receive, send)
async def _validate_request_headers(self, request: Request, send: Send) -> bool:
if not await self._validate_session(request, send):
return False
if not await self._validate_protocol_version(request, send):
return False
return True
# Protocol-version validation lives in the manager's era-routing: only
# values in `SUPPORTED_PROTOCOL_VERSIONS` (or no header at all) reach
# this transport, so the legacy version-gate is gone.
return await self._validate_session(request, send)
async def _validate_session(self, request: Request, send: Send) -> bool:
"""Validate the session ID in the request."""
@ -853,28 +848,6 @@ class StreamableHTTPServerTransport:
return True
async def _validate_protocol_version(self, request: Request, send: Send) -> bool:
"""Validate the protocol version header in the request."""
# Get the protocol version from the request headers
protocol_version = request.headers.get(MCP_PROTOCOL_VERSION_HEADER)
# If no protocol version provided, assume default version
if protocol_version is None:
protocol_version = DEFAULT_NEGOTIATED_VERSION
# Check if the protocol version is supported
if protocol_version not in SUPPORTED_PROTOCOL_VERSIONS:
supported_versions = ", ".join(SUPPORTED_PROTOCOL_VERSIONS)
response = self._create_error_response(
f"Bad Request: Unsupported protocol version: {protocol_version}. "
+ f"Supported versions: {supported_versions}",
HTTPStatus.BAD_REQUEST,
)
await response(request.scope, request.receive, send)
return False
return True
async def _replay_events(self, last_event_id: str, request: Request, send: Send) -> None:
"""Replays events that would have been sent after the specified event ID.
@ -894,7 +867,7 @@ class StreamableHTTPServerTransport:
if self.mcp_session_id: # pragma: no branch
headers[MCP_SESSION_ID_HEADER] = self.mcp_session_id
# Get protocol version from header (already validated in _validate_protocol_version)
# The manager only routes supported (or absent) header values to this transport
replay_protocol_version = request.headers.get(MCP_PROTOCOL_VERSION_HEADER, DEFAULT_NEGOTIATED_VERSION)
# Create SSE stream for replay