diff --git a/scripts/daily-sweep.sh b/scripts/daily-sweep.sh
index 26bc8a1..e1b44d2 100644
--- a/scripts/daily-sweep.sh
+++ b/scripts/daily-sweep.sh
@@ -94,6 +94,17 @@ else
   bad "NUT check on tsys1"
 fi
 
+# backup retention (#777): HA auto-backups accumulate ~750MB/day on a
+# 64GB disk. Keep the newest 2 automatic backups + f93af428 (beta seed)
+# + anything from the last 48h; prune older automatic_* tars.
+BK=$(VM_IP=pfv-bms-lan.knel.net VM_USER=root VM_PORT=22222 timeout 45 bash tests/remote.sh vm \
+  'cd /mnt/data/supervisor/backup 2>/dev/null && ls -1t automatic_*.tar 2>/dev/null | tail -n +3 | xargs -r rm -f && echo BK-OK' 2>/dev/null | grep -c BK-OK)
+if [ "${BK:-0}" -ge 1 ]; then
+  ok "backup retention applied (newest 2 automatic kept)"
+else
+  bad "backup retention pass on pfv-bms"
+fi
+
 # shellcheck disable=SC2016  # remote awk must see literal $5 on the far side
 DISKCHK=$(VM_IP=pfv-bms-lan.knel.net VM_USER=root VM_PORT=22222 timeout 45 bash tests/remote.sh vm \
   'df -m /mnt/data | awk "NR==2 {if (\$5+0 < 80) print \"DISK-OK\"}"' 2>/dev/null | grep -c DISK-OK)