diff --git a/infra/start.sh b/infra/start.sh
index 67c84ea..42ba092 100755
--- a/infra/start.sh
+++ b/infra/start.sh
@@ -217,3 +217,36 @@ UNIT
 systemctl --user daemon-reload
 systemctl --user enable --now hiy-update.timer
 echo "[hiy] Auto-update timer installed: systemctl --user status hiy-update.timer"
+
+# ── Install systemd timer for daily backup ────────────────────────────────────
+BACKUP_SERVICE="$SERVICE_DIR/hiy-backup.service"
+BACKUP_TIMER="$SERVICE_DIR/hiy-backup.timer"
+
+cat > "$BACKUP_SERVICE" <<UNIT
+[Unit]
+Description=HIY daily backup
+
+[Service]
+Type=oneshot
+Environment=PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/home/$(id -un)/.local/bin
+ExecStart=${SCRIPT_DIR}/backup.sh
+StandardOutput=journal
+StandardError=journal
+UNIT
+
+cat > "$BACKUP_TIMER" <<UNIT
+[Unit]
+Description=HIY daily backup at 03:00
+
+[Timer]
+OnCalendar=*-*-* 03:00:00
+Persistent=true
+Unit=hiy-backup.service
+
+[Install]
+WantedBy=timers.target
+UNIT
+
+systemctl --user daemon-reload
+systemctl --user enable --now hiy-backup.timer
+echo "[hiy] Backup timer installed: systemctl --user status hiy-backup.timer"