feat: Enable injection of httpx client factory for streamable-http mcp client

src/google/adk/tools/mcp_tool/mcp_session_manager.py

@@ -27,16 +27,17 @@
 from typing import Optional
 from typing import TextIO
 from typing import Union
+from typing import runtime_checkable
 
 import anyio
-from pydantic import BaseModel
+from pydantic import BaseModel, ConfigDict
 
 try:
   from mcp import ClientSession
   from mcp import StdioServerParameters
   from mcp.client.sse import sse_client
   from mcp.client.stdio import stdio_client
-  from mcp.client.streamable_http import streamablehttp_client
+  from mcp.client.streamable_http import streamablehttp_client, McpHttpClientFactory
 except ImportError as e:
 
   if sys.version_info < (3, 10):
@@ -101,11 +102,14 @@ class StreamableHTTPConnectionParams(BaseModel):
         when the connection is closed.
   """
 
+  model_config = ConfigDict(arbitrary_types_allowed=True, )
+
   url: str
   headers: dict[str, Any] | None = None
   timeout: float = 5.0
   sse_read_timeout: float = 60 * 5.0
   terminate_on_close: bool = True
+  httpx_client_factory: Optional[runtime_checkable(McpHttpClientFactory)] = None
 
 
 def retry_on_closed_resource(func):
@@ -285,6 +289,7 @@ def _create_client(self, merged_headers: Optional[Dict[str, str]] = None):
               seconds=self._connection_params.sse_read_timeout
           ),
           terminate_on_close=self._connection_params.terminate_on_close,
+          httpx_client_factory=self._connection_params.httpx_client_factory,
       )
     else:
       raise ValueError(

tests/unittests/tools/mcp_tool/test_mcp_session_manager.py

@@ -144,6 +144,30 @@ def test_init_with_streamable_http_params(self):
 
     assert manager._connection_params == http_params
 
+  @pytest.mark.asyncio
+  async def test_init_with_streamable_http_custom_httpx_factory(self):
+    """Test initialization with StreamableHTTPConnectionParams."""
+    import httpx
+    custom_httpx_client = httpx.AsyncClient()
+
+    def _httpx_factory(headers=None, timeout=None, auth=None):
+      return custom_httpx_client
+
+    custom_httpx_factory = Mock(side_effect=_httpx_factory)
+
+    http_params = StreamableHTTPConnectionParams(
+      url="https://example.com/mcp",
+      timeout=15.0,
+      httpx_client_factory=custom_httpx_factory,
+    )
+    manager = MCPSessionManager(http_params)
+
+    async with manager._create_client():
+      #assert factory was called
+      custom_httpx_factory.assert_called_once()
+
+
+
   def test_generate_session_key_stdio(self):
     """Test session key generation for stdio connections."""
     manager = MCPSessionManager(self.mock_stdio_connection_params)