---
title: "ChatStreamDelta"
---

Delta changes in streaming response


## Fields

| Field                                                                                                                                                                                | Type                                                                                                                                                                                 | Required                                                                                                                                                                             | Description                                                                                                                                                                          | Example                                                                                                                                                                              |
| ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `audio`                                                                                                                                                                              | [Optional[components.ChatAudioOutput]](../components/chataudiooutput.mdx)                                                                                                             | :heavy_minus_sign:                                                                                                                                                                   | N/A                                                                                                                                                                                  | \{<br/>"data": "UklGRnoGAABXQVZFZm10IBAAAAABAAEAQB8AAEAfAAABAAgAZGF0YQoGAACBhYqFbF1f",<br/>"expires_at": 1677652400,<br/>"id": "audio_abc123",<br/>"transcript": "Hello! How can I help you today?"<br/>} |
| `content`                                                                                                                                                                            | *OptionalNullable[str]*                                                                                                                                                              | :heavy_minus_sign:                                                                                                                                                                   | Message content delta                                                                                                                                                                | Hello                                                                                                                                                                                |
| `reasoning`                                                                                                                                                                          | *OptionalNullable[str]*                                                                                                                                                              | :heavy_minus_sign:                                                                                                                                                                   | Reasoning content delta                                                                                                                                                              | I need to                                                                                                                                                                            |
| `reasoning_details`                                                                                                                                                                  | List[[components.ReasoningDetailUnion](../components/reasoningdetailunion.mdx)]                                                                                                       | :heavy_minus_sign:                                                                                                                                                                   | Reasoning details for extended thinking models                                                                                                                                       | [<br/>\{<br/>"text": "Let me think about this...",<br/>"type": "text"<br/>}<br/>]                                                                                                     |
| `refusal`                                                                                                                                                                            | *OptionalNullable[str]*                                                                                                                                                              | :heavy_minus_sign:                                                                                                                                                                   | Refusal message delta                                                                                                                                                                | null                                                                                                                                                                                 |
| `role`                                                                                                                                                                               | [Optional[components.ChatStreamDeltaRole]](../components/chatstreamdeltarole.mdx)                                                                                                     | :heavy_minus_sign:                                                                                                                                                                   | The role of the message author                                                                                                                                                       | assistant                                                                                                                                                                            |
| `tool_calls`                                                                                                                                                                         | List[[components.ChatStreamToolCall](../components/chatstreamtoolcall.mdx)]                                                                                                           | :heavy_minus_sign:                                                                                                                                                                   | Tool calls delta                                                                                                                                                                     |                                                                                                                                                                                      |