fix: send CONNECTION_CLOSED error when SSE stream closes without event ID#2028
Open
kxbnb wants to merge 1 commit intomodelcontextprotocol:mainfrom
Open
fix: send CONNECTION_CLOSED error when SSE stream closes without event ID#2028kxbnb wants to merge 1 commit intomodelcontextprotocol:mainfrom
kxbnb wants to merge 1 commit intomodelcontextprotocol:mainfrom
Conversation
…t ID When an SSE stream closes without sending any events with IDs, _handle_sse_response silently returns instead of notifying the session. This leaves send_request waiting forever on a response that will never arrive. Send a JSONRPCError with CONNECTION_CLOSED to the read stream writer so the pending request fails with a clear error instead of hanging. Fixes modelcontextprotocol#1811 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
kxbnb
force-pushed
the
fix/sse-stream-closed-no-event-id
branch
from
5228e78 to
033dba3
Compare
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
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
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Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be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.
Summary
_handle_sse_responsepreviously returned silently, leavingsend_requesthanging foreverJSONRPCErrorwithCONNECTION_CLOSEDto the read stream writer so the pending request fails with a clear error instead of hanging indefinitelyFixes #1811
Reproduction
When a server closes the SSE stream before sending any events (e.g., server crash, network interruption before first event),
_handle_sse_responsefalls through to the reconnection check. Withlast_event_idstillNone, the function silently returns. The caller (send_request) is left waiting onresponse_stream_reader.receive()which never resolves.Test plan
test_handle_sse_response_sends_error_when_stream_closes_without_event_id— mocks an SSE response with zero events, verifiesCONNECTION_CLOSEDerror is sent to the read stream writertest_streamable_http.pytests pass🤖 Generated with Claude Code