# Append a message to a chat

**PUT** `/v1/chats/{chatId}`

**Operation ID**: `append`
**Summary**: Append a message to a chat
Signals the chat's workflow with a new user message. Returns 202 immediately.

## Tags
- Chats
## Parameters

- **chatId** (required) - path
  - Type: string

## Request Body

**Content-Type**: `application/json`

**Schema**: `AppendMessageRequest`

## Responses

### 202

Message accepted

### 401

Unauthorized

### 404

Chat not found

### 409

Chat is no longer running