# OpenResponsesReasoningSummaryTextDeltaEvent Event emitted when reasoning summary text delta is streamed ## Fields | Field | Type | Required | Description | | ------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------ | | `type` | [components.OpenResponsesReasoningSummaryTextDeltaEventType](../components/openresponsesreasoningsummarytextdeltaeventtype.md) | :heavy_check_mark: | N/A | | `item_id` | *str* | :heavy_check_mark: | N/A | | `output_index` | *float* | :heavy_check_mark: | N/A | | `summary_index` | *float* | :heavy_check_mark: | N/A | | `delta` | *str* | :heavy_check_mark: | N/A | | `sequence_number` | *float* | :heavy_check_mark: | N/A |