fix

frontend/src/preview/DocumentViewerPanel.tsx

@@ -65,7 +65,7 @@ interface DocumentViewerPanelProps extends DocumentSummarySectionProps {
   resolveFolderPath?: (doc: DocumentLike | null) => Array<{ id?: string | number; name?: string }>;
   variant?: 'viewer' | 'sidebar';
   onCollapsePanel?: () => void;
-  onMaximizePanel?: () => void;
+  onMaximizePanel?: (args: { documentIds: Array<string | number> }) => void;
 }
 
 
@@ -418,7 +418,11 @@ const panelRef = useRef<HTMLDivElement | HTMLFormElement | HTMLElement | null>(n
           className="icon-button"
           onClick={(event) => {
             event.stopPropagation();
-            onMaximizePanel?.(document?.id);
+            const targetId = document?.id;
+            if (targetId == null) {
+              return;
+            }
+            onMaximizePanel?.({ documentIds: [targetId] });
           }}
           aria-label="Maximize"
           title="Maximize"