name : UniqueFormHandle.php <?php namespace Statamic\Rules; use Closure; use Illuminate\Contracts\Validation\ValidationRule; use Statamic\Facades\Form; class UniqueFormHandle implements ValidationRule { public function validate(string $attribute, mixed $value, Closure $fail): void { if (Form::find($value)) { $fail('statamic::validation.unique_form_handle')->translate(); } } }