content_index: int

The index of the reasoning content part this delta is associated with.

delta: str

The text delta that was added to the reasoning content.

item_id: str

The ID of the item this reasoning text delta is associated with.

output_index: int

The index of the output item this reasoning text delta is associated with.

sequence_number: int

The sequence number of this event.

type: Literal["response.reasoning_text.delta"]

The type of the event. Always response.reasoning_text.delta.

agent: Optional[Agent]

The agent that owns this multi-agent streaming event.

agent_name: str

The canonical name of the agent that produced this item.