function updatePricingFields() {
    var model = document.querySelector('input[name="pricing_model"]:checked');
    if (!model) return;
    var val = model.value;
    document.getElementById('pricing-fields-fixed').style.display = val === 'fixed' ? '' : 'none';
    document.getElementById('pricing-fields-pwyw').style.display = val === 'pwyw' ? '' : 'none';
}