--- a/scripts/release.sh	2026-03-02 09:14:03.000000000 +0000
+++ b/scripts/release.sh	2026-03-02 10:41:55.000000000 +0000
@@ -1,4 +1,5 @@
 #!/bin/sh
 set -eu
 VERSION="$1"
+test -n "$VERSION" || { echo "usage: release.sh <version>" >&2; exit 2; }
 echo "tagging $VERSION"