> ## Documentation Index
> Fetch the complete documentation index at: https://openrouter-d02e98a0-mintlify-7021d5f4.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# ReasoningDeltaEvent - Python SDK

> ReasoningDeltaEvent method reference

<Warning>
  The Python SDK and docs are currently in beta.
  Report issues on [GitHub](https://github.com/OpenRouterTeam/python-sdk/issues).
</Warning>

Event emitted when reasoning text delta is streamed

## Fields

| Field             | Type                                                                                                       | Required             | Description |
| ----------------- | ---------------------------------------------------------------------------------------------------------- | -------------------- | ----------- |
| `content_index`   | *int*                                                                                                      | :heavy\_check\_mark: | N/A         |
| `delta`           | *str*                                                                                                      | :heavy\_check\_mark: | N/A         |
| `item_id`         | *str*                                                                                                      | :heavy\_check\_mark: | N/A         |
| `output_index`    | *int*                                                                                                      | :heavy\_check\_mark: | N/A         |
| `sequence_number` | *int*                                                                                                      | :heavy\_check\_mark: | N/A         |
| `type`            | [components.ReasoningDeltaEventType](/client-sdks/python/api-reference/components/reasoningdeltaeventtype) | :heavy\_check\_mark: | N/A         |