fix(vector): harden backup restore parity gates

scripts/vector-restore.sh

@@ -53,13 +53,14 @@ make_passfile "$active_host" "$active_port" "$active_database" "$active_user" \
 make_passfile "$target_host" "$target_port" "$target_database" "$target_user" \
   "$target_password_file" "$target_pass"
 
-identity_sql="SELECT system_identifier::text || ':' || d.oid::text FROM pg_control_system(), pg_database d WHERE d.datname = current_database()"
+identity_sql="SELECT system_identifier::text FROM pg_control_system()"
 active_identity=$(PGPASSFILE=$active_pass psql -XAt --host="$active_host" --port="$active_port" \
   --username="$active_user" --dbname="$active_database" --command="$identity_sql")
 target_identity=$(PGPASSFILE=$target_pass psql -XAt --host="$target_host" --port="$target_port" \
   --username="$target_user" --dbname="$target_database" --command="$identity_sql")
 [ "$active_identity" != "$target_identity" ] || {
-  echo "refusing restore: active source and target are the same database" >&2; exit 2;
+  echo "refusing restore: active source and target are on the same PostgreSQL cluster" >&2
+  exit 2
 }
 
 object_count=$(PGPASSFILE=$target_pass psql -XAt --host="$target_host" --port="$target_port" \
@@ -72,7 +73,8 @@ if [ "$object_count" != 0 ] && [ "$force" != 1 ]; then
   exit 2
 fi
 
-PGPASSFILE=$target_pass pg_restore --exit-on-error --clean --if-exists --no-owner \
+PGPASSFILE=$target_pass pg_restore --exit-on-error --single-transaction \
+  --clean --if-exists --no-owner \
   --host="$target_host" --port="$target_port" --username="$target_user" \
   --dbname="$target_database" "$input"
 echo "Vector restore completed into explicit target $target_host:$target_port/$target_database"