---
title: "Send a message to a Brain"
method: POST
path: "/api/v1/brains/{brain_id}/conversations/{conversation_id}/messages"
tags: ["brain conversations"]
---

# Send a message to a Brain

`POST /api/v1/brains/{brain_id}/conversations/{conversation_id}/messages`

## Request

- Base URL: `https://api.cadencz.com` (the document declares no server; this is the origin it was published from)
- URL: `https://api.cadencz.com/api/v1/brains/{brain_id}/conversations/{conversation_id}/messages`
- Auth: HTTP bearer

## Path parameters

- `brain_id` string, required
- `conversation_id` string, required

## Request body

- BrainChatRequest
  - `message` string, required
  - `mode` 'auto' | 'chat' | 'create' | 'refine'
  - `platform` string, nullable

## Response `200`

Successful Response

- BrainChatResponse
  - `conversation` BrainConversationRead, required
    - `id` string, required
    - `brain_id` string, required
    - `title` string, required
    - `status` string, required
    - `message_count` integer, required
    - `user_message_count` integer, required
    - `current_draft` string, required
    - `current_platform` string, nullable, required
    - `last_message_at` string, date-time, nullable, required
    - `summary_through_sequence` integer, required
    - `created_at` string, date-time, required
    - `updated_at` string, date-time, required
  - `user_message` BrainMessageRead, required
    - `id` string, required
    - `conversation_id` string, required
    - `role` 'user' | 'assistant', required
    - `sequence` integer, required
    - `content` string, required
    - `intent` string, nullable, required
    - `provider` string, nullable, required
    - `model` string, nullable, required
    - `agent_run_id` string, nullable, required
    - `metadata` object, required
    - `created_at` string, date-time, required
  - `assistant_message` BrainMessageRead, required
    - `id` string, required
    - `conversation_id` string, required
    - `role` 'user' | 'assistant', required
    - `sequence` integer, required
    - `content` string, required
    - `intent` string, nullable, required
    - `provider` string, nullable, required
    - `model` string, nullable, required
    - `agent_run_id` string, nullable, required
    - `metadata` object, required
    - `created_at` string, date-time, required
  - `intent` 'chat' | 'create' | 'refine', required
  - `draft` string, nullable, required

## Other responses

- `401`: Missing or invalid Supabase bearer token.
- `404`: The requested resource was not found.
- `422`: Validation Error
- `502`: The upstream provider rejected the request.
- `503`: Required infrastructure or provider config is unavailable.

---

[API](https://skmtc.dev/cadencz/apis/cadencz-api.md) · [All operations](https://skmtc.dev/cadencz/apis/cadencz-api/llms.txt) · [OpenAPI document](https://skmtc.dev/cadencz/apis/cadencz-api/revisions/3392fe5e93db?raw)