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.

sandbox.writeFiles([{
  path: 'run.sh',
  content: '#!/bin/bash\necho "ready"',
  mode: 0o755
}]);

See the documentation to learn more.