fix: report_progress missing passing related_request_id causes notifications not working in streaming-http

[alexsee]

This pull request fixes an issue related to report_progress that misses passing the related_request_id which causes notifications not working in stateless_http=True mode.

This issue was also reported for the FastMCP implementation in the Python MCP SDK: modelcontextprotocol/python-sdk#953

I also added a test for stateless_http=True mode introducing a parameterized pytest (not sure if you prefer having this in a separate file or keep it there).

[Copilot]

Pull Request Overview

This PR addresses an issue in the report_progress functionality by ensuring that the related_request_id is passed along, which fixes notifications not working in stateless_http mode. Key changes include:

• Adding the related_request_id parameter to the report_progress call in the server context.
• Updating server initialization and test fixtures to support the stateless_http mode configuration.
• Introducing a new parameterized pytest for testing the greet tool progress reporting.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
tests/client/test_streamable_http.py	Updated test fixtures and added tool testing for progress reporting.
src/fastmcp/server/context.py	Modified report_progress to include related_request_id in the payload.

Comments suppressed due to low confidence (2)

src/fastmcp/server/context.py:125

• Ensure that adding 'related_request_id' to the progress payload does not affect progress handler consumers. Verify that all clients or progress handlers are updated to either handle or ignore this additional parameter as necessary.

related_request_id=self.request_id,

tests/client/test_streamable_http.py:145

• The test asserts the progress handler receives three parameters, but the updated implementation now passes an extra 'related_request_id'. Adjust the test assertion or confirm that the extra parameter is properly handled (or ignored) in progress handler invocation.

progress_handler.assert_called_once_with(0.5, 1.0, "Greeting in progress")

[jlowin]

Thank you!

[jlowin]

I wonder why the low-level doesn't fill that in by default 🤔 But appreciate the fix!

[alexsee]

I wonder why the low-level doesn't fill that in by default

Thats a very good question and if the server is run in stateful mode, the requests are handled differently through the GET_stream (SSE) that is established. In that case, the related_request_id is not used.

For other logging methods, the related_request_id is actually set and it was added as part of the streaming-http implementation:

• https://github.com/modelcontextprotocol/python-sdk/blob/f3cd20c9200de001fb58f83a130ab83c6a6ed5fd/src/mcp/server/fastmcp/server.py#L976
• StreamableHttp - Server transport with state management modelcontextprotocol/python-sdk#553

For the context class in FastMCP (in this repo), these are also missing as I see.

What I'm not entirely sure is if there are any side effects that I may have introduced due to this change.