feat: Add option to pass custom kwargs to litellm.completion (#11423)

Co-authored-by: Ray Myers <ray.myers@gmail.com>

openhands/core/config/llm_config.py

@@ -47,6 +47,7 @@ class LLMConfig(BaseModel):
         seed: The seed to use for the LLM.
         safety_settings: Safety settings for models that support them (like Mistral AI and Gemini).
         for_routing: Whether this LLM is used for routing. This is set to True for models used in conjunction with the main LLM in the model routing feature.
+        completion_kwargs: Custom kwargs to pass to litellm.completion.
     """
 
     model: str = Field(default='claude-sonnet-4-20250514')
@@ -94,6 +95,10 @@ class LLMConfig(BaseModel):
         description='Safety settings for models that support them (like Mistral AI and Gemini)',
     )
     for_routing: bool = Field(default=False)
+    completion_kwargs: dict[str, Any] | None = Field(
+        default=None,
+        description='Custom kwargs to pass to litellm.completion',
+    )
 
     model_config = ConfigDict(extra='forbid')
 

openhands/llm/llm.py

@@ -196,6 +196,10 @@ class LLM(RetryMixin, DebugMixin):
         ):
             kwargs.pop('top_p', None)
 
+        # Add completion_kwargs if present
+        if self.config.completion_kwargs is not None:
+            kwargs.update(self.config.completion_kwargs)
+
         self._completion = partial(
             litellm_completion,
             model=self.config.model,

tests/unit/llm/test_llm.py

@@ -201,6 +201,28 @@ def test_llm_top_k_not_in_completion_when_none(mock_litellm_completion):
     llm.completion(messages=[{'role': 'system', 'content': 'Test message'}])
 
 
+@patch('openhands.llm.llm.litellm_completion')
+def test_completion_kwargs_passed_to_litellm(mock_litellm_completion):
+    # Create a config with custom completion_kwargs
+    config_with_completion_kwargs = LLMConfig(
+        completion_kwargs={'custom_param': 'custom_value', 'another_param': 42}
+    )
+    llm = LLM(config_with_completion_kwargs, service_id='test-service')
+
+    # Define a side effect function to check completion_kwargs are passed
+    def side_effect(*args, **kwargs):
+        assert 'custom_param' in kwargs
+        assert kwargs['custom_param'] == 'custom_value'
+        assert 'another_param' in kwargs
+        assert kwargs['another_param'] == 42
+        return {'choices': [{'message': {'content': 'Mocked response'}}]}
+
+    mock_litellm_completion.side_effect = side_effect
+
+    # Call completion
+    llm.completion(messages=[{'role': 'system', 'content': 'Test message'}])
+
+
 def test_llm_init_with_metrics():
     config = LLMConfig(model='gpt-4o', api_key='test_key')
     metrics = Metrics()