Problem
An MCP tool invoked over Streamable HTTP can emit logging or other server notifications, but the notifications are not reliably delivered before the request completes.
The external MCP conformance scenarios tools-call-with-logging and tools-call-with-progress expose this. Against effect@4.0.0-rc.112, the applicable adapter checks fail for the released protocol versions.
Observed behavior
The tool result is returned, but notification frames are missing or the streamed response is not consistently represented as Server-Sent Events.
The HTTP request lifecycle also treats the request-body EOF as though the MCP client disconnected. This can remove the negotiated client/profile state while asynchronous request work is still running.
Expected behavior
Notifications emitted as part of an active HTTP request should be delivered as valid SSE frames before the response stream completes. Finishing the POST request body must not disconnect the logical MCP session.
External regression scenarios
tools-call-with-loggingtools-call-with-progress
These checks are applicable protocol behavior and should pass rather than be skipped.
Regression coverage
Add an HTTP adapter test that invokes a tool which emits multiple notifications and then returns a result. Assert that every notification and the final result are observable in order from the streamed response.
Problem
An MCP tool invoked over Streamable HTTP can emit logging or other server notifications, but the notifications are not reliably delivered before the request completes.
The external MCP conformance scenarios
tools-call-with-loggingandtools-call-with-progressexpose this. Againsteffect@4.0.0-rc.112, the applicable adapter checks fail for the released protocol versions.Observed behavior
The tool result is returned, but notification frames are missing or the streamed response is not consistently represented as Server-Sent Events.
The HTTP request lifecycle also treats the request-body EOF as though the MCP client disconnected. This can remove the negotiated client/profile state while asynchronous request work is still running.
Expected behavior
Notifications emitted as part of an active HTTP request should be delivered as valid SSE frames before the response stream completes. Finishing the POST request body must not disconnect the logical MCP session.
External regression scenarios
tools-call-with-loggingtools-call-with-progressThese checks are applicable protocol behavior and should pass rather than be skipped.
Regression coverage
Add an HTTP adapter test that invokes a tool which emits multiple notifications and then returns a result. Assert that every notification and the final result are observable in order from the streamed response.