Api Restart Agent

Restart the SentinelX agent on a host (owner-only).

Low-risk: a restart just re-reads the existing config — it changes no permissions and touches no allowlist. It's how a config edit takes effect. Only the session cookie is required (no arm token): restarting can't escalate anything on its own.

The agent restarts itself, so its WebSocket drops mid-command and the call raises a disconnect. That's the EXPECTED success signal, not a failure — the agent reconnects to the hub on its own within seconds.