introduce a unified document viewer component.

frontend/src/app/useWorkspaceSurface.tsx

@@ -116,8 +116,8 @@ export const useWorkspaceSurface = ({
           <DocumentViewerPanel
             variant="sidebar"
             sidebarMode={sidebarMode}
-            onClosePanel={onClose}
-            onMaximizePanel={onOpenPreview}
+            onClose={onClose}
+            onMaximize={onOpenPreview}
             tagOptions={tagOptions}
             {...restDetailProps}
           />
@@ -194,7 +194,7 @@ export const useWorkspaceSurface = ({
         ensurePreviewData={ensurePreviewData}
         notifyApiError={notifyApiError}
         sidebarToggle={sidebarToggle}
-        onClosePanel={closeDocumentPreview}
+        onClose={closeDocumentPreview}
         resolveFolderPath={resolveFolderPath}
       />
     );

frontend/src/detail/PreviewZoomOverlay.tsx

@@ -1,7 +1,6 @@
 import React, { useEffect, useRef, useState } from 'react';
 import { createPortal } from 'react-dom';
-import PdfViewer from '../preview/PdfViewer';
-import MediaViewer from '../preview/MediaViewer';
+import UnifiedDocumentViewer from '../preview/UnifiedDocumentViewer';
 import PanelHeader from '../ui/PanelHeader';
 import { IconX, DownloadIcon, FileInfoIcon } from '../ui/icons';
 
@@ -14,16 +13,6 @@ interface PreviewZoomOverlayProps {
   document?: Document | null;
 }
 
-type DisplayKind = 'image' | 'pdf';
-
-const determineDisplayKind = (doc?: Document | null): DisplayKind => {
-  const type = doc?.mime_type?.toLowerCase?.() || '';
-  if (type.includes('pdf')) {
-    return 'pdf';
-  }
-  return 'image';
-};
-
 const PreviewZoomOverlay: React.FC<PreviewZoomOverlayProps> = ({
   open = false,
   onClose,
@@ -41,7 +30,6 @@ const PreviewZoomOverlay: React.FC<PreviewZoomOverlayProps> = ({
   }
 
   const downloadUrl = lastDocumentRef.current?.current_version?.download?.url;
-  const displayKind = determineDisplayKind(lastDocumentRef.current);
   const documentTitle = lastDocumentRef.current?.title || undefined;
 
   useEffect(() => {
@@ -172,23 +160,10 @@ const PreviewZoomOverlay: React.FC<PreviewZoomOverlayProps> = ({
             ref={scrollRef}
             tabIndex={-1}
           >
-            {displayKind === 'pdf' ? (
-              <PdfViewer
-                src={downloadUrl}
-                title={documentTitle}
-                className="preview-zoom__pdf-viewer"
-                viewportRef={scrollRef}
-              />
-            ) : (
-              <MediaViewer
-                src={downloadUrl}
-                alt={documentTitle}
-                className="preview-zoom__image"
-                draggable={false}
-                onClick={(e) => e.stopPropagation()}
-                mimeType={lastDocumentRef.current?.mime_type || undefined}
-              />
-            )}
+            <UnifiedDocumentViewer
+              document={lastDocumentRef.current}
+              viewportRef={scrollRef}
+            />
           </div>
         </div>
       </div>

frontend/src/preview/DocumentViewerLayout.tsx

@@ -1,8 +1,7 @@
 import { useCallback, useMemo, useRef } from 'react';
 import type { JSX } from 'react';
 import DocumentInfoPanel from '../documents/DocumentInfoPanel';
-import PdfViewer from './PdfViewer';
-import MediaViewer from './MediaViewer';
+import UnifiedDocumentViewer from './UnifiedDocumentViewer';
 
 import type { Document } from '../types/documents';
 
@@ -33,7 +32,6 @@ interface DocumentViewerLayoutProps {
   previewLoadingMessage?: string;
   layoutMode?: LayoutMode;
 }
-
 const DocumentViewerLayout = ({
   document,
   summaryProps = {},
@@ -49,43 +47,12 @@ const DocumentViewerLayout = ({
   const isStacked = layoutMode === 'stacked';
   const viewportRef = useRef<HTMLDivElement>(null);
 
-  const previewContent = useMemo(() => {
-    if (!document) {
-      return null;
-    }
-
-    const downloadUrl = document.current_version?.download?.url;
-    if (!downloadUrl) {
-      return null;
-    }
-
-    const normalizedMimeType = (document.mime_type || '').toLowerCase();
-    const normalizedFilename = document.filename;
-
-    const isPdf = normalizedMimeType === 'application/pdf'
-      || normalizedMimeType === 'application/x-pdf';
-
-    if (isPdf) {
-      const documentTitle = document.title;
-
-      return (
-        <PdfViewer
-          src={downloadUrl}
-          title={documentTitle ? `Preview of ${documentTitle}` : undefined}
-          viewportRef={viewportRef}
-        />
-      );
-    }
-
-    return (
-      <MediaViewer
-        src={downloadUrl}
-        mimeType={normalizedMimeType}
-        filename={normalizedFilename}
-        alt={`Preview of ${document.title}`}
-      />
-    );
-  }, [document, viewportRef]);
+  const previewContent = useMemo(() => (
+    <UnifiedDocumentViewer
+      document={document}
+      viewportRef={viewportRef}
+    />
+  ), [document, viewportRef]);
 
   const renderViewportPane = useCallback(() => (
     <div className="document-viewer__viewport" ref={viewportRef}>

frontend/src/preview/DocumentViewerPanel.tsx

@@ -39,10 +39,10 @@ interface DocumentViewerPanelProps extends DocumentSummarySectionProps {
   ensurePreviewData?: (docId: DocumentId, options?: { signal?: AbortSignal }) => Promise<Document | null>;
   notifyApiError?: (error: unknown, fallbackMessage?: string) => void;
   sidebarToggle?: ReactNode;
-  onClosePanel?: () => void;
+  onClose?: () => void;
   resolveFolderPath?: (doc: Document | null) => Array<{ id?: string; name?: string }>;
   variant?: 'viewer' | 'sidebar';
-  onMaximizePanel?: (args: { documentIds: Array<string> }) => void;
+  onMaximize?: (args: { documentIds: Array<string> }) => void;
   sidebarMode?: SidebarMode;
 }
 
@@ -95,10 +95,10 @@ const DocumentViewerPanel: React.FC<DocumentViewerPanelProps> = ({
   ensurePreviewData,
   notifyApiError,
   sidebarToggle = null,
-  onClosePanel,
+  onClose,
   resolveFolderPath,
   variant = 'viewer',
-  onMaximizePanel,
+  onMaximize,
   sidebarMode = 'overlay',
 }) => {
   const navigate = useNavigate();
@@ -299,7 +299,7 @@ const DocumentViewerPanel: React.FC<DocumentViewerPanelProps> = ({
     canZoom: Boolean(document),
   });
 
-  const maximizeButton = isSidebarVariant && onMaximizePanel
+  const maximizeButton = isSidebarVariant && onMaximize
     ? (
       <button
         type="button"
@@ -310,7 +310,7 @@ const DocumentViewerPanel: React.FC<DocumentViewerPanelProps> = ({
           if (targetId == null) {
             return;
           }
-          onMaximizePanel?.({ documentIds: [targetId] });
+          onMaximize?.({ documentIds: [targetId] });
         }}
         aria-label="Maximize"
         title="Maximize"
@@ -320,12 +320,12 @@ const DocumentViewerPanel: React.FC<DocumentViewerPanelProps> = ({
     )
     : null;
 
-  const closeButton = onClosePanel
+  const closeButton = onClose
     ? (
       <button
         type="button"
         className="icon-button"
-        onClick={() => onClosePanel?.()}
+        onClick={() => onClose?.()}
         aria-label="Close preview"
         title="Close preview"
       >

frontend/src/preview/UnifiedDocumentViewer.tsx

@@ -0,0 +1,57 @@
+import React, { useMemo } from 'react';
+import PdfViewer from './PdfViewer';
+import MediaViewer from './MediaViewer';
+import type { Document } from '../types/documents';
+
+interface UnifiedDocumentViewerProps {
+    document: Document | null;
+    viewportRef?: React.RefObject<HTMLDivElement>;
+}
+
+const UnifiedDocumentViewer: React.FC<UnifiedDocumentViewerProps> = ({
+    document,
+    viewportRef,
+}) => {
+    const content = useMemo(() => {
+        if (!document) {
+            return null;
+        }
+
+        const downloadUrl = document.current_version?.download?.url;
+        if (!downloadUrl) {
+            return null;
+        }
+
+        const normalizedMimeType = (document.mime_type || '').toLowerCase();
+        const normalizedFilename = document.filename;
+
+        const isPdf = normalizedMimeType === 'application/pdf'
+            || normalizedMimeType === 'application/x-pdf';
+
+        if (isPdf) {
+            return (
+                <PdfViewer
+                    src={downloadUrl}
+                    title={document.title}
+                    viewportRef={viewportRef}
+                />
+            );
+        }
+
+        return (
+            <MediaViewer
+                src={downloadUrl}
+                mimeType={normalizedMimeType}
+                filename={normalizedFilename}
+                alt={document.title}
+            />
+        );
+    }, [
+        document,
+        viewportRef,
+    ]);
+
+    return content;
+};
+
+export default UnifiedDocumentViewer;

frontend/src/styles/preview/preview-zoom.css

@@ -32,7 +32,7 @@
   --header-clearance: calc(2.5rem + 0.5rem);
 }
 
-.preview-zoom__image {
+.preview-zoom__scroll .document-viewer__object--image {
   width: auto;
   height: auto;
   box-shadow: 0 32px 120px var(--shadow-deep);
@@ -59,10 +59,7 @@
   outline: none;
 }
 
-
-
-
-.preview-zoom__pdf-viewer {
+.preview-zoom__scroll .document-viewer__object--pdf {
   width: 100%;
   height: 100%;
 }