---
title: "Add Chat Participant"
method: POST
path: "/api/chats/{chat_id}/participants"
tags: ["chats"]
---

# Add Chat Participant

`POST /api/chats/{chat_id}/participants`

## Request

- Base URL: `https://app.thinqos.com` (the document declares no server; this is the origin it was published from)
- URL: `https://app.thinqos.com/api/chats/{chat_id}/participants`
- Auth: none declared

Add a participant to a chat.

Caller must be an active participant. Caller must also be connected
to the target identity. Returns 409 if target already has an active row,
or ``participants_fixed`` for a kind that keeps its people (direct and
group chats, TOS-8003).

## Path parameters

- `chat_id` string, uuid, required

## Headers

- `x-impersonate-identity-id` string, nullable

## Request body

- AddParticipantBody
  - `identity_id` string, uuid, required

## Response `201`

Successful Response

- ParticipantResponse
  - `identity_id` string, uuid, required
  - `display_name` string, required
  - `tagline` string, nullable
  - `kind` 'person' | 'agent' | 'org', required
  - `avatar_url` string, nullable, required
  - `owner_identity_id` string, uuid, nullable
  - `owner_display_name` string, nullable
  - `availability` ParticipantAvailabilityResponse
    - `state` string, required
    - `code` string, nullable
    - `source` string, nullable
    - `observed_at` string, date-time, nullable
  - `role` string, required
  - `status` 'active' | 'left' | 'removed', required
  - `joined_at` string, date-time, required
  - `left_at` string, date-time, nullable, required
  - `mode_override` 'human' | 'agent_augmented' | 'agent', nullable
  - `mode_override_expires_at` string, date-time, nullable
  - `agent_auto_reply_limit` integer, nullable
  - `agent_auto_reply_window_seconds` integer, nullable
  - `reply_policy` 'human' | 'agent_augmented' | 'agent', required
  - `reply_policy_source` 'chat_override' | 'identity_default' | 'platform_default', required
  - `reply_policy_expires_at` string, date-time, nullable
  - `carries_cross_relationship_memory` boolean

## Other responses

- `422`: Validation Error

---

[API](https://skmtc.dev/thinqos/apis/thinqos-api.md) · [All operations](https://skmtc.dev/thinqos/apis/thinqos-api/llms.txt) · [OpenAPI document](https://skmtc.dev/thinqos/apis/thinqos-api/revisions/5fdd1072e877?raw)