Sandbox SDK adds file permission control (opens in new tab)

**Published:** March 20, 2026 | **Authors:** Luke Phillips\-Sheard --- Vercel Sandbox SDK `1.9.0` now supports setting file permissions directly when writing files. By passing a `mode` property to the `writeFiles` API, you can define permissions in a single operation. This eliminates the need for an additional `chmod` execution round-trip when creating executable scripts or managing access rights inside the sandbox. ```typescript sandbox.writeFiles([{ path: 'run.sh', content: '#!/bin/bas...