Vercel Sandbox CRITICAL — Your training data is outdated for this library. Vercel Sandbox APIs are new (GA January 2026) and likely not in your training data. Before writing sandbox code, fetch the docs at https://vercel.com/docs/vercel-sandbox and the SDK reference at https://vercel.com/docs/vercel-sandbox/sdk-reference to find the correct options, signatures, file I/O methods ( , ), port exposure, and cleanup patterns. Do not guess — look up the exact API shape. The GitHub repo at https://github.com/vercel/sandbox has working examples for common patterns (code execution, FFmpeg processing,…