Preflight proves the exact R20J Machine Git baseline, no active recovery operation and five healthy consistent slots. Backup captures adapter, network and recovery state. Apply isolates watcher/retry services, atomically installs one adapter, runs a no-mutation dry-run against isolated fresh state/cache/config binding, and restores services. Production pool freshness is not an installation prerequisite. Postcheck proves exact runtime-state preservation and one-file Git scope.