Sandbox - Visual Canvas
Push HTML content to a live-updating canvas server for visual previews, dashboards, and agent-driven UI.
Commands
/sandbox start - Start the canvas server (returns URL) /sandbox push <html> - Push HTML content to the canvas /sandbox reset - Reset canvas to blank state /sandbox screenshot - Take a screenshot of the current canvas /sandbox status - Show canvas server status and settings
Environment Variables
Variable Description
CANVAS_ALLOW_JS_EVAL
Enable JavaScript evaluation in canvas (default: false )
ALLOW_UNSAFE_SANDBOX
Enable unsafe sandbox mode (default: false )
Examples
/sandbox start /sandbox push <h1>Hello World</h1><p>Live preview</p> /sandbox screenshot /sandbox status /sandbox reset
How It Works
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/sandbox start launches a local HTTP server that serves the canvas page
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/sandbox push <html> sends HTML to the canvas, rendered in real time
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/sandbox screenshot captures the current canvas state as an image
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/sandbox reset clears all HTML, CSS, and JS from the canvas
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/sandbox status shows whether the server is running, the URL, and content sizes