diff --git a/src/agents/models/chatcmpl_stream_handler.py b/src/agents/models/chatcmpl_stream_handler.py
index 32f04acb..f099d86a 100644
--- a/src/agents/models/chatcmpl_stream_handler.py
+++ b/src/agents/models/chatcmpl_stream_handler.py
@@ -48,6 +48,9 @@ async def handle_stream(
usage: CompletionUsage | None = None
state = StreamingState()
+ is_reasoning_model = False
+ emit_reasoning_content = False
+ emit_content = False
async for chunk in stream:
if not state.started:
state.started = True
@@ -62,9 +65,16 @@ async def handle_stream(
continue
delta = chunk.choices[0].delta
+ reasoning_content = None
+ content = None
+ if hasattr(delta, "reasoning_content"):
+ reasoning_content = delta.reasoning_content
+ is_reasoning_model = True
+ if hasattr(delta, "content"):
+ content = delta.content
# Handle text
- if delta.content:
+ if reasoning_content or content:
if not state.text_content_index_and_output:
# Initialize a content tracker for streaming text
state.text_content_index_and_output = (
@@ -100,16 +110,59 @@ async def handle_stream(
),
type="response.content_part.added",
)
- # Emit the delta for this segment of content
- yield ResponseTextDeltaEvent(
- content_index=state.text_content_index_and_output[0],
- delta=delta.content,
- item_id=FAKE_RESPONSES_ID,
- output_index=0,
- type="response.output_text.delta",
- )
- # Accumulate the text into the response part
- state.text_content_index_and_output[1].text += delta.content
+
+ if reasoning_content is not None:
+ if not emit_reasoning_content:
+ emit_reasoning_content = True
+
+ reasoning_content_title = "# reasoning content\n\n"
+ # Emit the reasoning content title
+ yield ResponseTextDeltaEvent(
+ content_index=state.text_content_index_and_output[0],
+ delta=reasoning_content_title,
+ item_id=FAKE_RESPONSES_ID,
+ output_index=0,
+ type="response.output_text.delta",
+ )
+ # Accumulate the text into the response part
+ state.text_content_index_and_output[1].text += reasoning_content_title
+
+ # Emit the delta for this segment of content
+ yield ResponseTextDeltaEvent(
+ content_index=state.text_content_index_and_output[0],
+ delta=reasoning_content,
+ item_id=FAKE_RESPONSES_ID,
+ output_index=0,
+ type="response.output_text.delta",
+ )
+ # Accumulate the text into the response part
+ state.text_content_index_and_output[1].text += reasoning_content
+
+ if content is not None:
+ if not emit_content and is_reasoning_model:
+ emit_content = True
+ content_title = "\n\n# content\n\n"
+ # Emit the content title
+ yield ResponseTextDeltaEvent(
+ content_index=state.text_content_index_and_output[0],
+ delta=content_title,
+ item_id=FAKE_RESPONSES_ID,
+ output_index=0,
+ type="response.output_text.delta",
+ )
+ # Accumulate the text into the response part
+ state.text_content_index_and_output[1].text += content_title
+
+ # Emit the delta for this segment of content
+ yield ResponseTextDeltaEvent(
+ content_index=state.text_content_index_and_output[0],
+ delta=content,
+ item_id=FAKE_RESPONSES_ID,
+ output_index=0,
+ type="response.output_text.delta",
+ )
+ # Accumulate the text into the response part
+ state.text_content_index_and_output[1].text += content
# Handle refusals (model declines to answer)
if delta.refusal:
diff --git a/tests/test_openai_chatcompletions_stream.py b/tests/test_openai_chatcompletions_stream.py
index b82f2430..a321d98f 100644
--- a/tests/test_openai_chatcompletions_stream.py
+++ b/tests/test_openai_chatcompletions_stream.py
@@ -114,6 +114,104 @@ async def patched_fetch_response(self, *args, **kwargs):
assert completed_resp.usage.total_tokens == 12
+@pytest.mark.allow_call_model_methods
+@pytest.mark.asyncio
+async def test_stream_response_yields_events_for_reasoning_content(monkeypatch) -> None:
+ """
+ Validate that `stream_response` emits the correct sequence of events when
+ using reasoning model.
+ """
+ delta1 = ChoiceDelta(content=None)
+ setattr(delta1, "reasoning_content", "Okay") # noqa: B010
+ chunk1 = ChatCompletionChunk(
+ id="chunk-id",
+ created=1,
+ model="fake",
+ object="chat.completion.chunk",
+ choices=[Choice(index=0, delta=delta1)],
+ )
+
+ chunk2 = ChatCompletionChunk(
+ id="chunk-id",
+ created=1,
+ model="fake",
+ object="chat.completion.chunk",
+ choices=[Choice(index=0, delta=ChoiceDelta(content="He"))],
+ )
+ chunk3 = ChatCompletionChunk(
+ id="chunk-id",
+ created=1,
+ model="fake",
+ object="chat.completion.chunk",
+ choices=[Choice(index=0, delta=ChoiceDelta(content="llo"))],
+ )
+ async def fake_stream() -> AsyncIterator[ChatCompletionChunk]:
+ for c in (chunk1, chunk2, chunk3):
+ yield c
+
+ # Patch _fetch_response to inject our fake stream
+ async def patched_fetch_response(self, *args, **kwargs):
+ # `_fetch_response` is expected to return a Response skeleton and the async stream
+ resp = Response(
+ id="resp-id",
+ created_at=0,
+ model="fake-model",
+ object="response",
+ output=[],
+ tool_choice="none",
+ tools=[],
+ parallel_tool_calls=False,
+ )
+ return resp, fake_stream()
+
+ monkeypatch.setattr(OpenAIChatCompletionsModel, "_fetch_response", patched_fetch_response)
+ model = OpenAIProvider(use_responses=False).get_model("gpt-4")
+ output_events = []
+ async for event in model.stream_response(
+ system_instructions=None,
+ input="",
+ model_settings=ModelSettings(),
+ tools=[],
+ output_schema=None,
+ handoffs=[],
+ tracing=ModelTracing.DISABLED,
+ previous_response_id=None,
+ ):
+ output_events.append(event)
+ # We expect a response.created, then a response.output_item.added, content part added,
+ # two content delta events (for "He" and "llo"), a content part done, the assistant message
+ # output_item.done, and finally response.completed.
+ # There should be 8 events in total.
+ assert len(output_events) == 11
+ # First event indicates creation.
+ assert output_events[0].type == "response.created"
+ # The output item added and content part added events should mark the assistant message.
+ assert output_events[1].type == "response.output_item.added"
+ assert output_events[2].type == "response.content_part.added"
+ # Two text delta events.
+ assert output_events[3].type == "response.output_text.delta"
+ assert output_events[3].delta == "# reasoning content\n\n"
+ assert output_events[4].type == "response.output_text.delta"
+ assert output_events[4].delta == "Okay"
+ assert output_events[5].type == "response.output_text.delta"
+ assert output_events[5].delta == "\n\n# content\n\n"
+ assert output_events[6].type == "response.output_text.delta"
+ assert output_events[6].delta == "He"
+ assert output_events[7].type == "response.output_text.delta"
+ assert output_events[7].delta == "llo"
+ # After streaming, the content part and item should be marked done.
+ assert output_events[8].type == "response.content_part.done"
+ assert output_events[9].type == "response.output_item.done"
+ # Last event indicates completion of the stream.
+ assert output_events[10].type == "response.completed"
+ # The completed response should have one output message with full text.
+ completed_resp = output_events[10].response
+ assert isinstance(completed_resp.output[0], ResponseOutputMessage)
+ assert isinstance(completed_resp.output[0].content[0], ResponseOutputText)
+ assert (completed_resp.output[0].content[0].text ==
+ "# reasoning content\n\nOkay\n\n# content\n\nHello")
+
+
@pytest.mark.allow_call_model_methods
@pytest.mark.asyncio
async def test_stream_response_yields_events_for_refusal_content(monkeypatch) -> None: