I build the layer between your application and the model, and I make it hold.

# langchain-litellm · langchain_litellm/chat_models/litellm.py
# PR #161  remove global litellm module mutations from _client_params
 
     @property
     def _client_params(self) -> Dict[str, Any]:
-        """Get the parameters used for the openai client."""
-        set_model_value = self.model
-        if self.model_name is not None:
-            set_model_value = self.model_name
-        self.client.api_base = self.api_base
-        self.client.api_key = self.api_key
-        for named_api_key in [
-            "openai_api_key",
-            "azure_api_key",
-            "anthropic_api_key",
-            "replicate_api_key",
-            "cohere_api_key",
-            "openrouter_api_key",
-        ]:
-            if api_key_value := getattr(self, named_api_key):
-                setattr(
-                    self.client,
-                    named_api_key.replace("_api_key", "_key"),
-                    api_key_value,
-                )
-        self.client.organization = self.organization
+        """Get the parameters used for the OpenAI client."""
         creds: Dict[str, Any] = {
-            "model": set_model_value,
             "timeout": self.request_timeout,
             "api_base": self.api_base,
             "api_key": self.api_key,
+            "organization": self.organization,
         }
-        # Forward any extra headers to the client and include in params
         if self.extra_headers is not None:
-            # set attribute on client for runtime usage
-            setattr(self.client, "extra_headers", self.extra_headers)
             creds["extra_headers"] = self.extra_headers
         return {**self._default_params, **creds}
 

# and the test that keeps it fixed
# tests/unit_tests/test_litellm.py
 
+def test_client_params_does_not_mutate_litellm_globals() -> None:
+    """_client_params must not write instance config to litellm module globals. Fixes #132."""
+    before = {
+        "api_base": litellm.api_base,
+        "api_key": litellm.api_key,
+        "organization": getattr(litellm, "organization", None),
+    }
+
+    llm = ChatLiteLLM(
+        model="azure/gpt-4o",
+        api_base="https://my-azure.openai.azure.com",
+        api_key="azure-key",
+        organization="my-org",
+        extra_headers={"X-Custom": "value"},
+    )
+    params = llm._client_params
+
+    # globals must be untouched
+    assert litellm.api_base == before["api_base"]
+    assert litellm.api_key == before["api_key"]
+    assert getattr(litellm, "organization", None) == before["organization"]
+
+    # values must be present in the returned per-call params instead
+    assert params["api_base"] == "https://my-azure.openai.azure.com"
+    assert params["api_key"] == "azure-key"
+    assert params["organization"] == "my-org"
+    assert params["extra_headers"] == {"X-Custom": "value"}