---
title: "FusionCallInProgressEvent"
---

Emitted when an openrouter:fusion tool call begins executing.


## Fields

| Field                                                                                      | Type                                                                                       | Required                                                                                   | Description                                                                                |
| ------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------ |
| `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.FusionCallInProgressEventType](../components/fusioncallinprogresseventtype.mdx) | :heavy_check_mark:                                                                         | N/A                                                                                        |