Three modes
Pure SSH Action runs the CLI and stores state on the target server. Self-hosted Server Action calls the control-plane API. Product-grade Preview is owned by Cloud or a self-hosted control plane with preview policy, comments, checks, cleanup, audit, and quota.
Credential model
SSH keys, tokens, and secrets come from GitHub Secrets or trusted environments. Workflows may name secret references, but must not print secret values.
PR preview
The Action runs when a workflow subscribes to pull_request events. Close cleanup uses a separate close-event workflow; preview success leaves cleanup to that workflow.