fix(openai): handle Azure stream chunks without delta

Author: hassiebp

langfuse/openai.py

@@ -640,7 +640,9 @@ def _extract_streamed_openai_response(resource: Any, chunks: Any) -> Any:
             chunk = chunk.__dict__
 
         model = model or chunk.get("model", None) or None
-        usage = chunk.get("usage", None)
+        chunk_usage = chunk.get("usage", None)
+        if chunk_usage is not None:
+            usage = chunk_usage
 
         choices = chunk.get("choices", [])
 
@@ -649,11 +651,16 @@ def _extract_streamed_openai_response(resource: Any, chunks: Any) -> Any:
                 choice = choice.__dict__
             if resource.type == "chat":
                 delta = choice.get("delta", None)
-                finish_reason = choice.get("finish_reason", None)
+                choice_finish_reason = choice.get("finish_reason", None)
+                if choice_finish_reason is not None:
+                    finish_reason = choice_finish_reason
 
-                if _is_openai_v1():
+                if _is_openai_v1() and delta is not None:
                     delta = delta.__dict__
 
+                if delta is None:
+                    delta = {}
+
                 if delta.get("role", None) is not None:
                     completion["role"] = delta["role"]
 

tests/unit/test_openai.py

@@ -101,6 +101,64 @@ def _make_chat_stream_chunks():
     ]
 
 
+def _make_chat_stream_chunks_with_trailing_content_filter_chunk():
+    usage = SimpleNamespace(prompt_tokens=3, completion_tokens=1, total_tokens=4)
+
+    return [
+        SimpleNamespace(
+            model="gpt-4o-mini",
+            choices=[
+                SimpleNamespace(
+                    delta=SimpleNamespace(
+                        role="assistant",
+                        content="2",
+                        function_call=None,
+                        tool_calls=None,
+                    ),
+                    finish_reason=None,
+                )
+            ],
+            usage=None,
+        ),
+        SimpleNamespace(
+            model="gpt-4o-mini",
+            choices=[
+                SimpleNamespace(
+                    delta=SimpleNamespace(
+                        role=None,
+                        content=None,
+                        function_call=None,
+                        tool_calls=None,
+                    ),
+                    finish_reason="stop",
+                )
+            ],
+            usage=usage,
+        ),
+        SimpleNamespace(
+            model="",
+            choices=[
+                SimpleNamespace(
+                    delta=None,
+                    finish_reason=None,
+                    content_filter_offsets={
+                        "check_offset": 44,
+                        "start_offset": 44,
+                        "end_offset": 121,
+                    },
+                    content_filter_results={
+                        "hate": {"filtered": False, "severity": "safe"},
+                        "self_harm": {"filtered": False, "severity": "safe"},
+                        "sexual": {"filtered": False, "severity": "safe"},
+                        "violence": {"filtered": False, "severity": "safe"},
+                    },
+                )
+            ],
+            usage=None,
+        ),
+    ]
+
+
 def _make_single_chunk_stream():
     return SimpleNamespace(
         model="gpt-4o-mini",
@@ -315,6 +373,41 @@ def test_openai_stream_preserves_original_stream_contract(
     }
 
 
+def test_openai_stream_handles_trailing_azure_content_filter_chunk(
+    langfuse_memory_client, get_span, json_attr
+):
+    openai_client = lf_openai.OpenAI(api_key="test")
+    raw_stream = DummyOpenAIStream(
+        _make_chat_stream_chunks_with_trailing_content_filter_chunk(),
+        DummySyncResponse(),
+    )
+
+    with patch.object(openai_client.chat.completions, "_post", return_value=raw_stream):
+        stream = openai_client.chat.completions.create(
+            name="unit-openai-native-stream-azure-filter",
+            model="gpt-4o-mini",
+            messages=[{"role": "user", "content": "1 + 1 = ?"}],
+            temperature=0,
+            stream=True,
+        )
+
+    chunks = list(stream)
+    stream.close()
+
+    assert len(chunks) == 3
+
+    langfuse_memory_client.flush()
+    span = get_span("unit-openai-native-stream-azure-filter")
+
+    assert span.attributes[LangfuseOtelSpanAttributes.OBSERVATION_OUTPUT] == "2"
+    assert span.attributes["langfuse.observation.metadata.finish_reason"] == "stop"
+    assert json_attr(span, LangfuseOtelSpanAttributes.OBSERVATION_USAGE_DETAILS) == {
+        "prompt_tokens": 3,
+        "completion_tokens": 1,
+        "total_tokens": 4,
+    }
+
+
 def test_openai_stream_break_still_finalizes_generation(
     langfuse_memory_client, get_span
 ):