test(logging): cover object-response path in streaming responses assembly

tests/test_litellm/litellm_core_utils/test_litellm_logging.py

@@ -3747,3 +3747,46 @@ def test_get_assembled_streaming_response_handles_dict_response(logging_obj):
     assert assembled["usage"]["prompt_tokens"] == 11
     assert assembled["usage"]["completion_tokens"] == 7
     assert assembled["usage"]["total_tokens"] == 18
+
+
+def test_get_assembled_streaming_response_handles_object_response(logging_obj):
+    """
+    Companion to the dict-response regression: when ResponseCompletedEvent.response
+    is a proper ResponsesAPIResponse object carrying a ResponseAPIUsage, the
+    assembly helper must still transform usage into chat-completion shape.
+    """
+    from datetime import datetime
+
+    from litellm.types.llms.openai import (
+        ResponseAPIUsage,
+        ResponseCompletedEvent,
+        ResponsesAPIResponse,
+        ResponsesAPIStreamEvents,
+    )
+
+    response = ResponsesAPIResponse(
+        id="resp_obj",
+        created_at=0,
+        output=[],
+        usage=ResponseAPIUsage(input_tokens=3, output_tokens=4, total_tokens=7),
+    )
+    event = ResponseCompletedEvent(
+        type=ResponsesAPIStreamEvents.RESPONSE_COMPLETED,
+        response=response,
+    )
+    assert isinstance(event.response, ResponsesAPIResponse)
+
+    assembled = logging_obj._get_assembled_streaming_response(
+        result=event,
+        start_time=datetime.now(),
+        end_time=datetime.now(),
+        is_async=True,
+        streaming_chunks=[],
+    )
+
+    assert isinstance(assembled, ResponsesAPIResponse)
+    usage = assembled.usage
+    usage_dict = usage if isinstance(usage, dict) else usage.model_dump()
+    assert usage_dict["prompt_tokens"] == 3
+    assert usage_dict["completion_tokens"] == 4
+    assert usage_dict["total_tokens"] == 7