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[Bugfix] Emit reasoning_part events in simple streaming path for Resp… #35184

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Merged
chaunceyjiang merged 1 commit into from
Feb 27, 2026
Merged

[Bugfix] Emit reasoning_part events in simple streaming path for Resp… #35184

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21 changes: 21 additions & 0 deletions tests/entrypoints/openai/responses/test_simple.py
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@
from openai import OpenAI

from ....utils import RemoteOpenAIServer
from .conftest import validate_streaming_event_stack

MODEL_NAME = "Qwen/Qwen3-8B"

Expand Down Expand Up @@ -219,3 +220,23 @@ async def test_extra_sampling_params(client: OpenAI, model_name: str):
assert response.status in ["completed", "incomplete"]
assert len(response.output) > 0
assert response.output[0].content[0].text # Has text output


@pytest.mark.asyncio
@pytest.mark.parametrize("model_name", [MODEL_NAME])
async def test_streaming_types(
pairs_of_event_types: dict[str, str], client: OpenAI, model_name: str
):
stream = await client.responses.create(
model=model_name,
input="tell me a story about a cat in 20 words",
reasoning={"effort": "low"},
tools=[],
stream=True,
background=False,
)
events = []
async for event in stream:
events.append(event)

validate_streaming_event_stack(events, pairs_of_event_types)
79 changes: 57 additions & 22 deletions vllm/entrypoints/openai/responses/serving.py
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Original file line number Diff line number Diff line change
Expand Up @@ -85,6 +85,8 @@
ResponseCreatedEvent,
ResponseInProgressEvent,
ResponseInputOutputMessage,
ResponseReasoningPartAddedEvent,
ResponseReasoningPartDoneEvent,
ResponsesRequest,
ResponsesResponse,
ResponseUsage,
Expand Down Expand Up @@ -1339,6 +1341,19 @@ async def _process_simple_streaming_events(
),
)
)
yield _increment_sequence_number_and_return(
ResponseReasoningPartAddedEvent(
type="response.reasoning_part.added",
sequence_number=-1,
output_index=current_output_index,
item_id=current_item_id,
content_index=current_content_index,
part=ResponseReasoningTextContent(
text="",
type="reasoning_text",
),
)
)
else:
yield _increment_sequence_number_and_return(
ResponseOutputItemAddedEvent(
Expand All @@ -1354,22 +1369,21 @@ async def _process_simple_streaming_events(
),
)
)
yield _increment_sequence_number_and_return(
ResponseContentPartAddedEvent(
type="response.content_part.added",
sequence_number=-1,
output_index=current_output_index,
item_id=current_item_id,
content_index=current_content_index,
part=ResponseOutputText(
type="output_text",
text="",
annotations=[],
logprobs=[],
),
yield _increment_sequence_number_and_return(
ResponseContentPartAddedEvent(
type="response.content_part.added",
sequence_number=-1,
output_index=current_output_index,
item_id=current_item_id,
content_index=current_content_index,
part=ResponseOutputText(
type="output_text",
text="",
annotations=[],
logprobs=[],
),
)
)
)
current_content_index += 1
first_delta_sent = True
# todo(kebe7jun) tool call support

Expand Down Expand Up @@ -1397,6 +1411,19 @@ async def _process_simple_streaming_events(
text=reason_content,
)
)
yield _increment_sequence_number_and_return(
ResponseReasoningPartDoneEvent(
type="response.reasoning_part.done",
sequence_number=-1,
item_id=current_item_id,
output_index=current_output_index,
content_index=current_content_index,
part=ResponseReasoningTextContent(
text=reason_content,
type="reasoning_text",
),
)
)
current_content_index = 0
reasoning_item = ResponseReasoningItem(
type="reasoning",
Expand All @@ -1418,6 +1445,8 @@ async def _process_simple_streaming_events(
item=reasoning_item,
)
)
current_output_index += 1
current_item_id = str(uuid.uuid4())
yield _increment_sequence_number_and_return(
ResponseOutputItemAddedEvent(
type="response.output_item.added",
Expand All @@ -1432,8 +1461,6 @@ async def _process_simple_streaming_events(
),
)
)
current_output_index += 1
current_item_id = str(uuid.uuid4())
yield _increment_sequence_number_and_return(
ResponseContentPartAddedEvent(
type="response.content_part.added",
Expand All @@ -1449,7 +1476,6 @@ async def _process_simple_streaming_events(
),
)
)
current_content_index += 1
# reset previous delta messages
previous_delta_messages = []

Expand Down Expand Up @@ -1485,7 +1511,6 @@ async def _process_simple_streaming_events(
),
)
)
current_content_index += 1

previous_delta_messages.append(delta_message)
if previous_delta_messages:
Expand All @@ -1505,7 +1530,19 @@ async def _process_simple_streaming_events(
text=reason_content,
)
)
current_content_index += 1
yield _increment_sequence_number_and_return(
ResponseReasoningPartDoneEvent(
type="response.reasoning_part.done",
sequence_number=-1,
item_id=current_item_id,
output_index=current_output_index,
content_index=current_content_index,
part=ResponseReasoningTextContent(
text=reason_content,
type="reasoning_text",
),
)
)
reasoning_item = ResponseReasoningItem(
type="reasoning",
content=[
Expand Down Expand Up @@ -1543,7 +1580,6 @@ async def _process_simple_streaming_events(
item_id=current_item_id,
)
)
current_content_index += 1
part = ResponseOutputText(
text=final_content,
type="output_text",
Expand All @@ -1559,7 +1595,6 @@ async def _process_simple_streaming_events(
part=part,
)
)
current_content_index += 1
item = ResponseOutputMessage(
type="message",
role="assistant",
Expand Down