---
title: "Create Message"
method: POST
path: "/v1/omni-ai/threads/{thread_id}/messages"
tags: ["Omni AI"]
---

# Create Message

`POST /v1/omni-ai/threads/{thread_id}/messages`

Continue an existing conversation thread.

Appends a new user message to the thread and starts an assistant response.
Only one response may be active per thread at a time — if the previous turn
is still in progress, this endpoint returns **409 Conflict**. Wait for the
active response to reach a terminal status before submitting the next turn.

Poll the returned `response_id` via `GET /omni-ai/responses/{response_id}`
for assistant output.

## Path parameters

- `thread_id` string, uuid, required

## Request body

- CreateMessageRequest — Continue-thread message creation request body.
  - `account_id` integer, required
  - `capabilities` Capability[]
  - `text` string, required

## Response `200`

Message accepted. Poll the returned `response_id` for assistant output.

- object
  - `error` ApiError — A direct mapping of tonic::Status, for use in HTTP responses.
    - `code` integer, required — The error code is used to identify the nature of the error. It corresponds to an HTTP status code.
    - `details` object[]
    - `message` string, required — A human-readable message providing more details about the error.
  - `metadata` ResponseMetadata, required — Metadata for the response. This will always contain a request ID which can be used to identify the request to Clear Street for tracing, and optionally may include pagination data.
    - `next_page_token` string, byte, nullable — Base64URL-encoded pagination token
    - `page_number` integer, nullable — Pagination. Included if this was a GET (list) response
    - `previous_page_token` string, byte, nullable — Base64URL-encoded pagination token
    - `request_id` string, required — A unique ID for this request, generated upon ingestion of the request.
    - `total_items` integer, nullable — Total number of items available (not just in this page).
    - `total_pages` integer, nullable — Total number of pages available.
  - `data` CreateMessageResponse, required — Response payload for continuing a thread with a new message.
    - `response_id` string, uuid, required
    - `thread_id` string, uuid, required
    - `user_message_id` string, uuid, required

## Other responses

- `400` — Invalid request
- `409` — Thread already has an active response — wait for it to complete
- `422` — Malformed request payload
- `500` — Internal server error

---

[API](https://skmtc.net/clear-street/apis/clear-street-trading-api.md) · [All operations](https://skmtc.net/clear-street/apis/clear-street-trading-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/clear-street/clear-street-trading-api/revisions/80e6fb2644e0/schema)