fix: pass related_request_id in Context.report_progress()

Progress notifications sent via Context.report_progress() were silently
dropped in stateless HTTP / SSE transports because the call to
send_progress_notification() was missing the related_request_id parameter.
The SSE transport relies on this field to route notifications back to the
correct client stream.

Add related_request_id=self.request_id to the send_progress_notification()
call, consistent with how send_log_message() already passes it.

Reported-by: hubbard-zlee
Github-Issue: #2001

Author: weiguangli-io

src/mcp/server/fastmcp/server.py

@@ -1177,6 +1177,7 @@ async def report_progress(self, progress: float, total: float | None = None, mes
             progress=progress,
             total=total,
             message=message,
+            related_request_id=self.request_id,
         )
 
     async def read_resource(self, uri: str | AnyUrl) -> Iterable[ReadResourceContents]:

tests/issues/test_176_progress_token.py

@@ -36,6 +36,12 @@ async def test_progress_token_zero_first_call():
 
     # Verify progress notifications
     assert mock_session.send_progress_notification.call_count == 3, "All progress notifications should be sent"
-    mock_session.send_progress_notification.assert_any_call(progress_token=0, progress=0.0, total=10.0, message=None)
-    mock_session.send_progress_notification.assert_any_call(progress_token=0, progress=5.0, total=10.0, message=None)
-    mock_session.send_progress_notification.assert_any_call(progress_token=0, progress=10.0, total=10.0, message=None)
+    mock_session.send_progress_notification.assert_any_call(
+        progress_token=0, progress=0.0, total=10.0, message=None, related_request_id="test-request"
+    )
+    mock_session.send_progress_notification.assert_any_call(
+        progress_token=0, progress=5.0, total=10.0, message=None, related_request_id="test-request"
+    )
+    mock_session.send_progress_notification.assert_any_call(
+        progress_token=0, progress=10.0, total=10.0, message=None, related_request_id="test-request"
+    )

tests/issues/test_2001_progress_related_request_id.py

@@ -0,0 +1,41 @@
+from unittest.mock import AsyncMock, MagicMock
+
+import pytest
+
+from mcp.server.fastmcp import Context
+from mcp.shared.context import RequestContext
+
+pytestmark = pytest.mark.anyio
+
+
+async def test_report_progress_passes_related_request_id():
+    """Test that Context.report_progress() passes related_request_id to
+    send_progress_notification so that progress notifications are correctly
+    routed in stateless HTTP / SSE transports.
+
+    Regression test for https://github.com/modelcontextprotocol/python-sdk/issues/2001
+    """
+    mock_session = AsyncMock()
+    mock_session.send_progress_notification = AsyncMock()
+
+    mock_meta = MagicMock()
+    mock_meta.progressToken = "test-progress-token"
+
+    request_context = RequestContext(
+        request_id="req-42",
+        session=mock_session,
+        meta=mock_meta,
+        lifespan_context=None,
+    )
+
+    ctx = Context(request_context=request_context, fastmcp=MagicMock())
+
+    await ctx.report_progress(0.5, total=1.0, message="halfway")
+
+    mock_session.send_progress_notification.assert_called_once_with(
+        progress_token="test-progress-token",
+        progress=0.5,
+        total=1.0,
+        message="halfway",
+        related_request_id="req-42",
+    )