improvement: pdf generation added to cases feature.

frontend/src/components/ui/lab/CasesPage.tsx

@@ -75,6 +75,7 @@ export function CasesPage() {
   const [loadingList, setLoadingList] = useState(false);
   const [loadingDetail, setLoadingDetail] = useState(false);
   const [updatingImportant, setUpdatingImportant] = useState(false);
+  const [updatingExternalCode, setUpdatingExternalCode] = useState(false);
   const [assignableStaff, setAssignableStaff] = useState<AssignableTaskStaff[]>([]);
   const [assigningTaskId, setAssigningTaskId] = useState<string | null>(null);
   const [commentCount, setCommentCount] = useState(0);
@@ -330,6 +331,25 @@ export function CasesPage() {
     }
   }
 
+  async function handleCaseExternalCodeChange(externalCode: string | null) {
+    if (!selectedCaseId || !canEdit || !selectedCase) return;
+
+    const previousCase = selectedCase;
+    setSelectedCase({ ...selectedCase, externalCode });
+
+    setUpdatingExternalCode(true);
+    toast.setError('');
+    try {
+      const response = await casesApi.setCaseExternalCode(selectedCaseId, externalCode);
+      setSelectedCase(response.data);
+    } catch (error: unknown) {
+      setSelectedCase(previousCase);
+      toast.showError(getUserFacingError(error, tErrors, t('errorUpdateExternalCode')));
+    } finally {
+      setUpdatingExternalCode(false);
+    }
+  }
+
   const filterSelectClass = `${FORM_SELECT_CLASS} w-full min-w-0 rounded-md py-1.5 text-xs sm:py-2 sm:text-sm`;
 
   return (
@@ -550,6 +570,8 @@ export function CasesPage() {
               canEditImportant={canEdit}
               updatingImportant={updatingImportant}
               onImportantChange={(checked) => void handleCaseImportantToggle(checked)}
+              updatingExternalCode={updatingExternalCode}
+              onExternalCodeChange={(code) => void handleCaseExternalCodeChange(code)}
               assignableStaff={assignableStaff}
               canAssignTasks={canEdit}
               assigningTaskId={assigningTaskId}