<Info>This API is in beta. Endpoints, fields, and behavior may still change, so avoid depending on it in production.</Info>

Replaces an earlier user message and rebuilds from there. Base44 rolls the app back to just before that message, then runs your new one in its place.

Use it to reword a request that took the AI in the wrong direction, instead of piling a correction on top. Everything the AI did from message_id onwards is undone first, so those changes are gone. To keep them, send a new message with Send chat message instead.

The request stays open until the new turn settles, so it can take several minutes. It consumes credits like any other turn.

Queued messages wait while this runs, and the queue carries on afterward unless you paused it. If the new turn ends waiting on a tool call, the queue stays paused until you answer it with Submit tool-call input.

Set an Idempotency-Key or X-Request-ID header before you send. A network retry carrying the same value is ignored rather than run a second time and charged again.

A 200 response does not mean the turn succeeded. Two cases come back as a 200.

• The turn ran and finished. status.state is ready and the app is idle again.
• The turn ran and failed. status.state is error, and status.error_source says where it failed. A value of paywall means the app's workspace has no credits left.

<Warning>The response includes fields beyond the ones documented here. Don't rely on undocumented response fields, as they can change at any time. Send only the fields documented here. Other request fields are not supported and their behavior can change.</Warning>

{
  "content": "Add a contact form to the home page, with a phone field",
  "message_id": "7f3a1c88-52d4-4a0e-9b31-2c6f0d8e4a19"
}

{
  "id": "6820f3a4e7b91d003c45a1f2",
  "name": "My CRM",
  "status": {
    "state": "ready",
    "details": "Publishing app",
    "request_id": "a1b2c3d4e5f67890abcdef12",
    "last_updated_date": "2026-08-02T14:30:00Z",
    "error_source": "build",
    "paywall_context": {
      "billing_organization_id": "67e0b12c4d8a3f005b21c9e4",
      "user_id": "6706af53b9c1e2004a37d85f",
      "evaluated_at": "2026-08-02T14:30:00Z"
    }
  },
  "conversation": {
    "id": "1f0c2b7a-9d51-4c3e-8a62-7b4d5e6f8a90",
    "messages": [
      {
        "id": "7f3a1c88-52d4-4a0e-9b31-2c6f0d8e4a19",
        "role": "assistant",
        "content": "I added a contact form to the home page.",
        "file_urls": [
          "https://example.com/mockup.png"
        ],
        "checkpoint_id": "6886b8d390dc7e2f4a2c91b3",
        "tool_calls": [
          {
            "id": "toolu_01A9FJd3kP2mNqRs7VwXyZ4b",
            "name": "create_file",
            "status": "waiting_for_user_input",
            "requires_user_input": true,
            "arguments_string": "{\"file_path\": \"src/pages/Home.jsx\", \"content\": \"export default function Home() {}\"}"
          }
        ],
        "usage": {
          "prompt_tokens": 18432,
          "completion_tokens": 742,
          "credits_charged": 1.5
        },
        "metadata": {
          "created_date": "2026-08-02T14:30:00",
          "created_by_email": "developer@example.com"
        }
      }
    ]
  }
}