---
title: "AddThreadParticipantBody"
description: "Request body for a ThreadParticipant operation."
section: "Reference"
group: "Types"
order: 235
---

## Definition

```ts
interface AddThreadParticipantBody {
  threadId: string;
  userId?: string | undefined;
  agentId?: string | undefined;
  swarmId?: string | undefined;
  externalIdentity?: string | undefined;
  displayName?: string | undefined;
}
```

## Fields

| Field              | Type                  | Notes                                                                                         |
| ------------------ | --------------------- | --------------------------------------------------------------------------------------------- |
| `threadId`         | `string`              | `required` — Thread to add the participant to.                                                |
| `userId`           | `string \| undefined` | `optional` — Set to add an Aeontel user as a participant.                                     |
| `agentId`          | `string \| undefined` | `optional` — Set to add an agent as a participant.                                            |
| `swarmId`          | `string \| undefined` | `optional` — Set to add a swarm as a participant.                                             |
| `externalIdentity` | `string \| undefined` | `optional` — Opaque identity for an external visitor (typically from a deployed-app session). |
| `displayName`      | `string \| undefined` | `optional` — Required when adding a visitor; optional otherwise.                              |