Planning a maintenance window

Plan a disruptive step ahead of time, with who needs telling and by when.

 ❯ Plan pve1's kernel update for next week
 ❯ When should pve1's update happen?

Hostwarden runs the same radius as what a reboot would hit, reads every Downtime notice: inside it for the audience and lead time, and proposes a window: it says whether the update must, should or can happen sooner, from any pending reboot, the longest lead time in the radius, and the host's own automatic-restart slot. Once you pick a window, it writes a plan in memory/plans/ with the steps, the radius, the notify-by date and the rollback, and each affected host gets a Downtime: line — nothing runs yet. Asked later ("run plan pve1-kernel"), Hostwarden re-reads the radius, shows what changed, and puts the steps to you once more before running them. It also writes a short notice for other admins — three lines to paste into chat, or a fuller email — and records automatic reboots and restarts a host would do on its own, so a slot nobody planned still shows up as a known one.