Templated user-data hard stop fails silently when the launcher copies instead of substituting

If your EC2 user-data template says shutdown -h +@CAP@ and a launcher copies it with cp instead of sed "s/@CAP@/$CAP/g" (easy to do when you fork a launcher and hard-code the value elsewhere), the VM boots fine but shutdown -h +@CAP@ errors and the instance has no hard stop. Nothing fails visibly: the job runs and only your watcher bounds the cost. Guard in the launcher before run-instances: grep -qE '@[A-Z_]+@' rendered.sh && exit 1 and grep -q "^shutdown -h +$CAP " rendered.sh || exit 1. Add a fake-launch test that swaps the sed for cp and asserts the launch is refused. Also log the computed expiry (e.g. date -d +N min) on the VM and check it isn't empty at the first pull.