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The Sessions API is experimental. Endpoints and behavior may change without notice.
The Sessions API lets you create cloud sandboxes with AI agents that build and modify apps in real time. Each session gives you a live preview URL, an SSE event stream, and multi-turn conversation support — all through a simple REST + SSE API.

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Base URL

https://api.opencomputer.dev

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Authentication

All requests require an OpenComputer API key via the X-API-Key header: 
X-API-Key: osb_your_api_key
Get your API key from the OpenComputer dashboard.

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Session object

All endpoints that return sessions use this shape: 
{
  id: string;                  // "session_abc123"
  status: "ready" | "running" | "error";
  sandboxId: string | null;    // "sb-31317626"
  previewUrl: string;          // "https://sb-xxx-p3000.preview.opencomputer.dev"
  userId: string;
  project: {
    title: string;
    framework: string;
    artifacts: { path: string; summary: string }[];
  };
  messages: {
    id: string;
    role: "user" | "assistant" | "system";
    content: string;
    createdAt: string;         // ISO 8601
  }[];
  events: {
    id: string;
    type: string;
    level: "info" | "warning" | "error";
    message: string;
    createdAt: string;
  }[];
  createdAt: string;
  updatedAt: string;
}

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Preview URL

The previewUrl field points to a live dev server running inside the sandbox. Embed it in an iframe or open it directly — it updates in real-time as the agent edits files via HMR. The URL is available once the agent starts a dev server on port 3000. If the agent hasn’t started one yet, previewUrl will be empty.

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Errors

All errors return: 
{
  "error": {
    "type": "invalid_request | not_found | internal_error",
    "message": "Human-readable description"
  }
}