A box is a sandboxed Linux container in the cloud with a shell, a filesystem, git, an optional headless Chromium, and public URLs for its ports. Everything here goes through the remote Upstash MCP server. There is no SDK to install and no API key in the environment (recording videos is the exception, see below): the server forwards the session's OAuth token to the Box API, and screenshot bytes travel from the box to Blob without passing through the server. When to take work into a box - The user asks for it: remote, in a sandbox, in the cloud, in a box, not on my machine. - The deliverable is…