diff --git a/docs/system-recovery.md b/docs/system-recovery.md
index f535064..b8003c3 100644
--- a/docs/system-recovery.md
+++ b/docs/system-recovery.md
@@ -12,6 +12,12 @@ subvolumes beneath `@root` are refused. Boot and fstab must select the filesyste
 UUID plus `subvol=@root`, never a numeric root subvolume ID. `@home` and VM disks
 stored there survive restoration; files stored elsewhere in `@root` roll back.
 
+This includes `/var/lib/hydra-update`: a full root restoration also restores the
+checkpoint's runtime update receipts and replay floor. The signed updater's
+monotonic sequence guarantee applies to runtime apply/recovery/rollback, not to
+replacing the entire root with an older checkpoint. Check the available signed
+release again after base recovery.
+
 Record the Btrfs filesystem UUID and ESP PARTUUID at installation. From the live
 ISO, inspect the plan before executing it: