// Minimal sandbox.js - just listens for sandbox-load and writes the content window.addEventListener("message", (event) => { if (event.data.type === "sandbox-load") { // Write the complete HTML (which includes runtime + user code) document.open(); document.write(event.data.code); document.close(); } }); // Signal ready to parent window.parent.postMessage({ type: "sandbox-ready" }, "*");