Cloudflare Sandbox SDK vs SPACE

Cloudflare Sandbox SDK

Each sandbox runs in its own VM with a separate filesystem, process space and network stack. No hosted API. You deploy and secure a Worker before an agent can call anything, and the starter has no auth.

SPACE

Once deployed, SPACE's native API has a public OpenAPI 3.1 contract, stable error codes with a retryable flag and 24-hour idempotency keys, and egress and credential controls sit outside the VM. A person must first deploy it on a Linux x86_64 host with KVM and Kubernetes. Version 0.8.0 has no tagged release, changelog or public container images.

Cloudflare Sandbox SDK

1. Derive the sandbox ID from the authenticated user, as the docs advise. IDs aren't secrets
2. Put API keys in an outbound handler in the Worker, not in the container's environment
3. Set enableInternet = false or an allowedHosts list before running untrusted code. Internet access is on by default
4. Check that a restored backup has every directory you expect. Backups of 10 MB or more have open bugs
5. Start new projects on 1.0. The 0.x library only gets fixes until 31 December 2026

SPACE

1. Ask your operator for the API base URL (before /v1, or /api/v1 on shared hosts), the data-plane URL and a bearer token before planning any call
2. Poll the returned operation until it succeeds and the sandbox is running before creating a command. A 202 response is not readiness
3. Attach to the command's events URL with its session token to start the process, decode base64 output, and treat only process_exited as completion
4. Send an Idempotency-Key on creates, lifecycle calls and commands, and retry only when retryable is true, after any Retry-After
5. Save output as it arrives. Reconnecting with Last-Event-ID returns resync_required, not the missed output