Standard checkboxes allow multiple selections. If you enable the "Enforce Single Selection" option, we inject a custom validation script. This script counts how many boxes are checked and shows an error if the user selects more than one, effectively turning checkboxes into radio buttons.
// Gather all checkbox inputs into an array: [true, false, true...]
const checks = [input.pass, input.fail];
// Filter to keep only 'true' ones, then count them.
valid = (checks.filter(v => v).length > 1)
? 'Error: Select only one option.'
: true;