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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"
  }
}