diff --git a/litellm/integrations/langfuse/langfuse.py b/litellm/integrations/langfuse/langfuse.py
index 825f1b89e90..ee67228841a 100644
--- a/litellm/integrations/langfuse/langfuse.py
+++ b/litellm/integrations/langfuse/langfuse.py
@@ -638,9 +638,11 @@ class LangFuseLogger:
         elif response_obj is not None and isinstance(response_obj, litellm.ResponsesAPIResponse):
             input = prompt
             output = self._get_responses_api_content_for_langfuse(response_obj)
-        elif response_obj is not None and isinstance(response_obj, (DecisionsResponse, OpenAIDecisionResponse)):
-            input = prompt
-            output = response_obj.model_dump(mode="json", exclude={"usage"})
+        elif isinstance(response_obj, (DecisionsResponse, OpenAIDecisionResponse)):
+            return (  # pyright: ignore[reportUnknownVariableType]  # prompt is the caller's untyped dict, as in every branch
+                prompt,
+                response_obj.model_dump(mode="json", include={"answers"}),
+            )
         elif (
             kwargs.get("call_type") is not None
             and kwargs.get("call_type") == "_arealtime"
diff --git a/tests/unit/integrations/langfuse/langfuse_expected_request_body/systemone.json b/tests/unit/integrations/langfuse/langfuse_expected_request_body/systemone.json
new file mode 100644
index 00000000000..50e1ea18848
--- /dev/null
+++ b/tests/unit/integrations/langfuse/langfuse_expected_request_body/systemone.json
@@ -0,0 +1,38 @@
+{
+    "name": "litellm-asystemone",
+    "parent_span_id": null,
+    "attributes": {
+        "langfuse.observation.cost_details": {
+            "total": 1.1886e-05
+        },
+        "langfuse.observation.input": {
+            "messages": [
+                {
+                    "content": "{\"state\": \"Customer writes: my payout has failed three days in a row.\", \"questions\": {\"urgent\": {\"type\": \"noul\", \"instructions\": \"Is this urgent?\"}}}",
+                    "role": "user"
+                }
+            ]
+        },
+        "langfuse.observation.level": "DEFAULT",
+        "langfuse.observation.metadata.api_base": "https://openrouter.ai/api/alpha/decisions",
+        "langfuse.observation.model.name": "typesafe/jev-1.13",
+        "langfuse.observation.model.parameters": {},
+        "langfuse.observation.output": {
+            "answers": {
+                "urgent": {
+                    "noul": 0.87,
+                    "type": "noul"
+                }
+            }
+        },
+        "langfuse.observation.type": "generation",
+        "langfuse.observation.usage_details": {
+            "cache_creation_input_tokens": 0,
+            "cache_read_input_tokens": 0,
+            "input": 283,
+            "output": 20,
+            "total": 303
+        },
+        "langfuse.trace.name": "litellm-asystemone"
+    }
+}
diff --git a/tests/unit/integrations/langfuse/test_langfuse.py b/tests/unit/integrations/langfuse/test_langfuse.py
index ecaecebf276..747ebd1cc1f 100644
--- a/tests/unit/integrations/langfuse/test_langfuse.py
+++ b/tests/unit/integrations/langfuse/test_langfuse.py
@@ -445,7 +445,7 @@ async def test_langfuse_logging_systemone(
             **({"id": response_id} if response_id is not None else {}),
             "model": "typesafe/jev-1.13",
             "answers": answers,
-            "usage": {"input_tokens": 283, "output_tokens": 20},
+            "usage": {"input_tokens": 283, "output_tokens": 20, "cost": 1.1886e-05},
         }
     )
     await litellm.asystemone(
@@ -457,23 +457,7 @@ async def test_langfuse_logging_systemone(
     )
     await _flush_langfuse()
     assert upstream.call_count == 1
-    generations: Final = tuple(
-        TypeAdapter(dict[str, object]).validate_python(span["attributes"])
-        for span in _exported_spans(route)
-        if span["trace_id"] == resolve_trace_id(trace_id)
-        and TypeAdapter(dict[str, object]).validate_python(span["attributes"]).get("langfuse.observation.type")
-        == "generation"
-    )
-    assert len(generations) == 1
-    assert generations[0]["langfuse.observation.usage_details"] == {
-        "input": 283,
-        "output": 20,
-        "total": 303,
-        "cache_creation_input_tokens": 0,
-        "cache_read_input_tokens": 0,
-    }
-    output: Final = TypeAdapter(dict[str, object]).validate_python(generations[0]["langfuse.observation.output"])
-    assert output["answers"] == answers
+    _expected_generation(route, "systemone.json", trace_id)
 
 
 @pytest.mark.asyncio