fix: config dict should not be mutated directly (#162)

Author: mathislucka

src/deepset_mcp/api/transport.py

@@ -6,6 +6,7 @@
 import time
 from collections.abc import AsyncIterator
 from contextlib import AbstractAsyncContextManager, asynccontextmanager
+from copy import deepcopy
 from dataclasses import dataclass
 from typing import Any, Generic, Literal, Protocol, TypeVar, cast, overload
 
@@ -198,8 +199,10 @@ def __init__(
         config : dict, optional
             Configuration for httpx.AsyncClient, e.g., {'timeout': 10.0}
         """
-        config = config or {}
-        # Ensure auth header
+        # We deepcopy the config so that we don't mutate it when used for subsequent initializations
+        config = deepcopy(config) or {}
+
+        # Merge auth and other config headers
         headers = config.pop("headers", {})
         headers.setdefault("Authorization", f"Bearer {api_key}")
         # Build client kwargs

src/deepset_mcp/config.py

@@ -38,4 +38,4 @@
 DEEPSET_DOCS_DEFAULT_SHARE_URL = "https://cloud.deepset.ai/shared_prototypes?share_token=prototype_eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE3ODM0MjE0OTguNTk5LCJhdWQiOiJleHRlcm5hbCB1c2VyIiwiaXNzIjoiZEMiLCJ3b3Jrc3BhY2VfaWQiOiI4YzI0ZjExMi1iMjljLTQ5MWMtOTkzOS1hZTkxMDRhNTQyMWMiLCJ3b3Jrc3BhY2VfbmFtZSI6ImRjLWRvY3MtY29udGVudCIsIm9yZ2FuaXphdGlvbl9pZCI6ImNhOWYxNGQ0LWMyYzktNDYwZC04ZDI2LWY4Y2IwYWNhMDI0ZiIsInNoYXJlX2lkIjoiY2Y3MTA3ODAtOThmNi00MzlmLThiNzYtMmMwNDkyODNiMDZhIiwibG9naW5fcmVxdWlyZWQiOmZhbHNlfQ.5j6DCNRQ1_KB8lhIJqHyw2hBIleEW1_Y_UBuH6MTYY0"
 DOCS_SEARCH_TOOL_NAME = "search_docs"
 
-DEFAULT_CLIENT_HEADER = {"headers": {"user-agent": f"deepset-mcp/{__version__}"}}
+DEFAULT_CLIENT_HEADER = {"headers": {"User-Agent": f"deepset-mcp/{__version__}"}}

test/unit/api/test_transport.py

@@ -229,3 +229,44 @@ async def test_close(self, transport: AsyncTransport, mock_httpx_client: AsyncMo
         await transport.close()
 
         mock_httpx_client.aclose.assert_called_once()
+
+    async def test_config_not_mutated_on_repeated_initialization(self) -> None:
+        """Test that config dict is not mutated when creating multiple AsyncTransport instances."""
+        # Create a config with headers
+        original_config = {
+            "timeout": 30.0,
+            "headers": {"Custom-Header": "value", "Another-Header": "another-value"},
+            "follow_redirects": True,
+        }
+
+        with patch("httpx.AsyncClient") as mock_client_class:
+            # First initialization - should not mutate original config
+            AsyncTransport(base_url="https://api.example.com", api_key="test-key-1", config=original_config)
+
+            # Verify the config still has headers after first initialization
+            assert "headers" in original_config
+            assert original_config["headers"] == {"Custom-Header": "value", "Another-Header": "another-value"}
+
+            # Second initialization with same config - should still work
+            AsyncTransport(base_url="https://api.example.com", api_key="test-key-2", config=original_config)
+
+            # Verify the config still has headers after second initialization
+            assert "headers" in original_config
+            assert original_config["headers"] == {"Custom-Header": "value", "Another-Header": "another-value"}
+            assert original_config["timeout"] == 30.0
+            assert original_config["follow_redirects"] is True
+
+            # Verify both clients were created with the expected headers
+            assert mock_client_class.call_count == 2
+
+            # Check first call
+            first_call_args = mock_client_class.call_args_list[0][1]
+            assert first_call_args["headers"]["Authorization"] == "Bearer test-key-1"
+            assert first_call_args["headers"]["Custom-Header"] == "value"
+            assert first_call_args["headers"]["Another-Header"] == "another-value"
+
+            # Check second call
+            second_call_args = mock_client_class.call_args_list[1][1]
+            assert second_call_args["headers"]["Authorization"] == "Bearer test-key-2"
+            assert second_call_args["headers"]["Custom-Header"] == "value"
+            assert second_call_args["headers"]["Another-Header"] == "another-value"