fix: correct SSE transport routing per MCP SDK docs #4
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
There was a problem hiding this comment.
Pull request overview
This pull request fixes incorrect ASGI handler usage in the SSE transport layer by aligning the implementation with MCP SDK documentation patterns. The changes address compatibility issues where Route() was incorrectly used with ASGI handlers instead of Request-based endpoints.
Changes:
- Modified
handle_sseto accept aRequestobject instead of raw ASGI parameters (scope, receive, send) - Changed POST message routing from
Route()toMount()with direct ASGI handler - Removed unused
handle_messageswrapper function
The previous implementation incorrectly used ASGI handlers (scope, receive, send) with Starlette Route(), which doesn't work. Route() expects endpoint functions that take a Request object. Changes per MCP SDK documentation (mcp/server/sse.py): - handle_sse now takes Request and uses request._send - Returns Response() to avoid NoneType error on disconnect - Messages endpoint uses Mount() with ASGI handler directly - Removed unused handle_messages function
mfaferek93
force-pushed
the
fix/sse-transport-routing
branch
from
87ba96c to
02191cc
Compare
bburda
approved these changes
Feb 1, 2026
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Pull Request
Summary
The previous implementation incorrectly used ASGI handlers (scope, receive, send) with Starlette Route(), which doesn't work. Route() expects endpoint functions that take a Request object.
Changes per MCP SDK documentation (mcp/server/sse.py):
Issue
Link the related issue (required):
Type
Testing
How was this tested / how should reviewers verify it?
Checklist
poetry run ruff check src/ tests/)poetry run ruff format --check src/ tests/)poetry run mypy src/)poetry run python run_tests.py)