Fix fastmcp stateless_http deprecation warning (#12108)

Co-authored-by: openhands <openhands@all-hands.dev>
Co-authored-by: Rohit Malhotra <rohitvinodmalhotra@gmail.com>

openhands/server/app.py

@@ -36,7 +36,7 @@ from openhands.server.shared import conversation_manager, server_config
 from openhands.server.types import AppMode
 from openhands.version import get_version
 
-mcp_app = mcp_server.http_app(path='/mcp')
+mcp_app = mcp_server.http_app(path='/mcp', stateless_http=True)
 
 
 def combine_lifespans(*lifespans):

openhands/server/routes/mcp.py

@@ -25,9 +25,7 @@ from openhands.server.user_auth import (
 )
 from openhands.storage.data_models.conversation_metadata import ConversationMetadata
 
-mcp_server = FastMCP(
-    'mcp', stateless_http=True, mask_error_details=True, dependencies=None
-)
+mcp_server = FastMCP('mcp', mask_error_details=True)
 
 HOST = f'https://{os.getenv("WEB_HOST", "app.all-hands.dev").strip()}'
 CONVERSATION_URL = HOST + '/conversations/{}'

tests/unit/server/routes/test_mcp_routes.py

@@ -1,3 +1,4 @@
+import warnings
 from unittest.mock import AsyncMock, patch
 
 import pytest
@@ -7,6 +8,38 @@ from openhands.server.routes.mcp import get_conversation_link
 from openhands.server.types import AppMode
 
 
+def test_mcp_server_no_stateless_http_deprecation_warning():
+    """Test that mcp_server is created without stateless_http deprecation warning.
+
+    This test verifies the fix for the fastmcp deprecation warning:
+    'Providing `stateless_http` when creating a server is deprecated.
+    Provide it when calling `run` or as a global setting instead.'
+
+    The fix moves the stateless_http parameter from FastMCP() constructor
+    to the http_app() method call.
+    """
+    with warnings.catch_warnings(record=True) as w:
+        warnings.simplefilter('always')
+
+        # Import the mcp_server which triggers FastMCP creation
+        from openhands.server.routes.mcp import mcp_server
+
+        # Check that no deprecation warning about stateless_http was raised
+        stateless_http_warnings = [
+            warning
+            for warning in w
+            if issubclass(warning.category, DeprecationWarning)
+            and 'stateless_http' in str(warning.message)
+        ]
+
+        assert len(stateless_http_warnings) == 0, (
+            f'Unexpected stateless_http deprecation warning: {stateless_http_warnings}'
+        )
+
+        # Verify mcp_server was created successfully
+        assert mcp_server is not None
+
+
 @pytest.mark.asyncio
 async def test_get_conversation_link_non_saas_mode():
     """Test get_conversation_link in non-SAAS mode."""