Implementation:Openai Openai python Response Reasoning Summary Part Added

Knowledge Sources	Openai_Openai_python OpenAI API Reference
Domains	API_Types, Responses_API
Last Updated	2026-02-15 00:00 GMT

Overview

Concrete type for representing an event emitted when a new reasoning summary part is added during a streaming response, provided by the openai-python SDK.

Description

ResponseReasoningSummaryPartAddedEvent is a Pydantic model representing the response.reasoning_summary_part.added streaming event. It is emitted when a new summary part begins within a reasoning item. The event carries a part object (containing text and type fields), the item_id linking it to the parent reasoning item, output_index and summary_index for positional tracking, and a sequence_number for stream ordering.

Usage

Import this type when handling streaming events from reasoning models and you need to detect the start of a new reasoning summary part.

Code Reference

Source Location

• Repository: openai-python
• File: src/openai/types/responses/response_reasoning_summary_part_added_event.py

Signature

class ResponseReasoningSummaryPartAddedEvent(BaseModel):
    """Emitted when a new reasoning summary part is added."""

    item_id: str
    output_index: int
    part: Part
    sequence_number: int
    summary_index: int
    type: Literal["response.reasoning_summary_part.added"]

Import

from openai.types.responses import ResponseReasoningSummaryPartAddedEvent

I/O Contract

Fields

Name	Type	Required	Description
item_id	str	Yes	The ID of the item this summary part is associated with.
output_index	int	Yes	The index of the output item this summary part is associated with.
part	Part	Yes	The summary part that was added. Contains text (str) and type (Literal["summary_text"]).
sequence_number	int	Yes	The sequence number of this event.
summary_index	int	Yes	The index of the summary part within the reasoning summary.
type	Literal["response.reasoning_summary_part.added"]	Yes	The type of the event. Always response.reasoning_summary_part.added.

Usage Examples

import openai

client = openai.OpenAI()

stream = client.responses.create(
    model="o3-mini",
    input="Explain quantum entanglement step by step.",
    stream=True,
)

for event in stream:
    if event.type == "response.reasoning_summary_part.added":
        print(f"New summary part at index {event.summary_index}: {event.part.text}")

Related Pages

• Environment:Openai_Openai_python_Python_3_9_Plus