feat: enforce singleton active invoice template per language during updates and revisions

services/template/DocumentTemplateService.js

@@ -135,6 +135,14 @@ class DocumentTemplateService {
         }, uow.connection);
       }
 
+      // Enforce singleton active invoice template per lang
+      if (state === 'active' && current.type === 'invoice') {
+        await DocumentTemplateRepository.deactivateOtherActiveInvoices({
+          excludeId: id,
+          lang: current.lang,
+        }, uow.connection);
+      }
+
       const updated = await DocumentTemplateRepository.findById(id, uow.connection);
       await uow.commit();
       logger.info('DocumentTemplateService.updateTemplateState:success', { id, state });
@@ -186,6 +194,15 @@ class DocumentTemplateService {
         }, uow.connection);
       }
 
+      // If new template is active and is an invoice template, deactivate other active invoices for same lang
+      const effectiveType = data.type || previous.type;
+      if (nextState === 'active' && effectiveType === 'invoice') {
+        await DocumentTemplateRepository.deactivateOtherActiveInvoices({
+          excludeId: created.id,
+          lang: (data.lang || previous.lang),
+        }, uow.connection);
+      }
+
       // Deactivate previous (requirement: deactive the previous one)
       await DocumentTemplateRepository.updateState(previousId, 'inactive', uow.connection);