diff --git a/packages/ui/src/components/views/FilesView.tsx b/packages/ui/src/components/views/FilesView.tsx
index 5b236b28..ed66f23b 100644
--- a/packages/ui/src/components/views/FilesView.tsx
+++ b/packages/ui/src/components/views/FilesView.tsx
@@ -42,7 +42,7 @@ import { useDebouncedValue } from '@/hooks/useDebouncedValue';
 import { useFileSearchStore } from '@/stores/useFileSearchStore';
 import { useDeviceInfo } from '@/lib/device';
 import { cn, getModifierLabel, getRevealLabelKey, hasModifier } from '@/lib/utils';
-import { getLanguageFromExtension, getImageMimeType, isDrawioFile, isImageFile } from '@/lib/toolHelpers';
+import { getLanguageFromExtension, getImageMimeType, isDrawioFile, isImageFile, isPdfFile } from '@/lib/toolHelpers';
 import { getRuntimeUrlResolver } from '@/lib/runtime-url';
 import { refreshRuntimeUrlAuthToken } from '@/lib/runtime-auth';
 import { getRuntimeApiBaseUrl } from '@/lib/runtime-switch';
@@ -823,9 +823,10 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
   const [fileContent, setFileContent] = React.useState<string>('');
   const { isPlaying: isTTSPlaying, play: playTTS, stop: stopTTS } = useMessageTTS();
   const [fileLoading, setFileLoading] = React.useState(false);
-  const [fileError, setFileError] = React.useState<string | null>(null);
-  const [desktopImageSrc, setDesktopImageSrc] = React.useState<string>('');
-  const [imageAssetAuthReadyKey, setImageAssetAuthReadyKey] = React.useState('');
+  const [fileError, setFileError] = React.useState<string | null>(null);
+  const [desktopImageSrc, setDesktopImageSrc] = React.useState<string>('');
+  const [imageAssetAuthReadyKey, setImageAssetAuthReadyKey] = React.useState('');
+  const [pdfAssetAuthReadyKey, setPdfAssetAuthReadyKey] = React.useState('');
 
   const [loadedFilePath, setLoadedFilePath] = React.useState<string | null>(null);
 
@@ -1693,8 +1694,9 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
     setDesktopImageSrc('');
     setLoadedFilePath(null);
 
-    const selectedIsImage = isImageFile(node.path);
-    const isSvg = node.path.toLowerCase().endsWith('.svg');
+    const selectedIsImage = isImageFile(node.path);
+    const isSvg = node.path.toLowerCase().endsWith('.svg');
+    const selectedIsPdf = isPdfFile(node.path);
 
     if (isMobile) {
       setShowMobilePageContent(true);
@@ -1709,13 +1711,21 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
     }
 
     // Web: binary images should not be read as utf8.
-    if (!runtime.isDesktop && selectedIsImage && !isSvg) {
-      setFileContent('');
-      setDraftContent('');
-      setLoadedFilePath(node.path);
-      setFileLoading(false);
-      return;
-    }
+    if (!runtime.isDesktop && selectedIsImage && !isSvg) {
+      setFileContent('');
+      setDraftContent('');
+      setLoadedFilePath(node.path);
+      setFileLoading(false);
+      return;
+    }
+
+    if (selectedIsPdf) {
+      setFileContent('');
+      setDraftContent('');
+      setLoadedFilePath(node.path);
+      setFileLoading(false);
+      return;
+    }
 
     setFileLoading(true);
 
@@ -2189,8 +2199,9 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
     });
   }
 
-  const isSelectedImage = Boolean(selectedFile?.path && isImageFile(selectedFile.path));
-  const isSelectedSvg = Boolean(selectedFile?.path && selectedFile.path.toLowerCase().endsWith('.svg'));
+  const isSelectedImage = Boolean(selectedFile?.path && isImageFile(selectedFile.path));
+  const isSelectedSvg = Boolean(selectedFile?.path && selectedFile.path.toLowerCase().endsWith('.svg'));
+  const isSelectedPdf = Boolean(selectedFile?.path && isPdfFile(selectedFile.path));
   const pendingNavigationTargetPath = React.useMemo(
     () => normalizePath(pendingFileNavigation?.path ?? ''),
     [pendingFileNavigation?.path],
@@ -2200,23 +2211,24 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
       && pendingNavigationTargetPath
       && selectedFilePath
       && selectedFilePath === pendingNavigationTargetPath
-      && !fileLoading
-      && !fileError
-      && !isSelectedImage,
-  );
+      && !fileLoading
+      && !fileError
+      && !isSelectedImage
+      && !isSelectedPdf,
+  );
 
   const displaySelectedPath = React.useMemo(() => {
     return getDisplayPath(root, selectedFilePath);
   }, [selectedFilePath, root]);
 
-  const canCopy = Boolean(selectedFile && (!isSelectedImage || isSelectedSvg) && fileContent.length > 0);
-  const canCopyPath = Boolean(selectedFile && displaySelectedPath.length > 0);
-  const canEdit = Boolean(selectedFile && !selectedFileIsOutsideWorkspace && !isSelectedImage && files.writeFile && fileContent.length <= MAX_VIEW_CHARS);
+  const canCopy = Boolean(selectedFile && (!isSelectedImage || isSelectedSvg) && !isSelectedPdf && fileContent.length > 0);
+  const canCopyPath = Boolean(selectedFile && displaySelectedPath.length > 0);
+  const canEdit = Boolean(selectedFile && !selectedFileIsOutsideWorkspace && !isSelectedImage && !isSelectedPdf && files.writeFile && fileContent.length <= MAX_VIEW_CHARS);
   const isMarkdown = Boolean(selectedFile?.path && isMarkdownFile(selectedFile.path));
   const isJson = Boolean(selectedFile?.path && isJsonFile(selectedFile.path));
   const isHtml = Boolean(selectedFile?.path && isHtmlFile(selectedFile.path));
   const isDrawio = Boolean(selectedFile?.path && isDrawioFile(selectedFile.path));
-  const isTextFile = Boolean(selectedFile && !isSelectedImage);
+  const isTextFile = Boolean(selectedFile && !isSelectedImage && !isSelectedPdf);
   const canUseShikiFileView = isTextFile && !isMarkdown && !isDrawio && !(isHtml && htmlViewMode === 'preview');
   const staticLanguageExtension = React.useMemo(
     () => (selectedFilePath ? languageByExtension(selectedFilePath) : null),
@@ -2554,7 +2566,7 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
       return;
     }
 
-    if (fileError || isSelectedImage) {
+    if (fileError || isSelectedImage || isSelectedPdf) {
       setPendingFileNavigation(null);
       pendingNavigationCycleRef.current = { key: '', attempts: 0 };
       return;
@@ -2623,9 +2635,10 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
     draftContent,
     editorViewReadyNonce,
     fileError,
-    fileLoading,
-    isSelectedImage,
-    loadedFilePath,
+    fileLoading,
+    isSelectedImage,
+    isSelectedPdf,
+    loadedFilePath,
     handleSelectFile,
     pendingFileNavigation,
     root,
@@ -2654,7 +2667,7 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
       return;
     }
 
-    if (fileLoading || loadedFilePath !== targetPath || fileError || isSelectedImage) {
+    if (fileLoading || loadedFilePath !== targetPath || fileError || isSelectedImage || isSelectedPdf) {
       return;
     }
 
@@ -2672,9 +2685,10 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
     confirmDiscardOpen,
     fileError,
     fileLoading,
-    handleSelectFile,
-    isSelectedImage,
-    loadedFilePath,
+    handleSelectFile,
+    isSelectedImage,
+    isSelectedPdf,
+    loadedFilePath,
     pendingFileFocusPath,
     root,
     selectedFile?.path,
@@ -2813,6 +2827,10 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
   const imageAssetAuthKey = selectedFile?.path && isSelectedImage && !runtime.isDesktop && !isSelectedSvg
     ? `${selectedFile.path}|${selectedFileReadOptions.allowOutsideWorkspace ? 'outside' : 'workspace'}|${selectedFileReadOptions.outsideFileGrant ?? ''}`
     : '';
+
+  const pdfAssetAuthKey = selectedFile?.path && isSelectedPdf
+    ? `${selectedFile.path}|${selectedFileReadOptions.allowOutsideWorkspace ? 'outside' : 'workspace'}|${selectedFileReadOptions.outsideFileGrant ?? ''}`
+    : '';
 
   React.useEffect(() => {
     if (!imageAssetAuthKey) {
@@ -2833,9 +2851,35 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
     };
   }, [imageAssetAuthKey]);
 
-  const isImageAssetAuthLoading = Boolean(imageAssetAuthKey && imageAssetAuthReadyKey !== imageAssetAuthKey);
+  const isImageAssetAuthLoading = Boolean(imageAssetAuthKey && imageAssetAuthReadyKey !== imageAssetAuthKey);
+
+  React.useEffect(() => {
+    if (!pdfAssetAuthKey) {
+      setPdfAssetAuthReadyKey('');
+      return;
+    }
+
+    let cancelled = false;
+    setPdfAssetAuthReadyKey('');
+    void refreshRuntimeUrlAuthToken(getRuntimeApiBaseUrl())
+      .then((token) => {
+        if (!cancelled && token) setPdfAssetAuthReadyKey(pdfAssetAuthKey);
+      })
+      .catch((error) => {
+        if (!cancelled) {
+          setFileError(error instanceof Error ? error.message : t('filesView.error.readFileFailed'));
+          setPdfAssetAuthReadyKey(pdfAssetAuthKey);
+        }
+      });
+
+    return () => {
+      cancelled = true;
+    };
+  }, [pdfAssetAuthKey, t]);
+
+  const isPdfAssetAuthLoading = Boolean(pdfAssetAuthKey && pdfAssetAuthReadyKey !== pdfAssetAuthKey);
 
-  const imageSrc = selectedFile?.path && isSelectedImage
+  const imageSrc = selectedFile?.path && isSelectedImage
     ? (runtime.isDesktop
       ? (isSelectedSvg
         ? `data:${getImageMimeType(selectedFile.path)};utf8,${encodeURIComponent(fileContent)}`
@@ -2847,7 +2891,25 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
           allowOutsideWorkspace: selectedFileReadOptions.allowOutsideWorkspace ? 'true' : undefined,
           outsideFileGrant: selectedFileReadOptions.outsideFileGrant,
         }) : ''))
-    : '';
+    : '';
+
+  const pdfSrc = selectedFile?.path && isSelectedPdf && pdfAssetAuthReadyKey === pdfAssetAuthKey
+    ? getRuntimeUrlResolver().authenticatedAsset('/api/fs/raw', {
+      path: selectedFile.path,
+      allowOutsideWorkspace: selectedFileReadOptions.allowOutsideWorkspace ? 'true' : undefined,
+      outsideFileGrant: selectedFileReadOptions.outsideFileGrant,
+    })
+    : '';
+
+  const renderPdfPreview = React.useCallback((file: FileNode) => (
+    <div className="h-full overflow-hidden bg-[var(--surface-background)]">
+      <iframe
+        src={pdfSrc}
+        className="h-full w-full border-0"
+        title={file.name}
+      />
+    </div>
+  ), [pdfSrc]);
 
   React.useEffect(() => {
     let cancelled = false;
@@ -3045,7 +3107,7 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
           </DropdownMenuContent>
         </DropdownMenu>
 
-        {!isSelectedImage && (
+        {!isSelectedImage && !isSelectedPdf && (
           <>
             {withTooltip(wrapLines ? t('filesView.editor.disableLineWrap') : t('filesView.editor.enableLineWrap'),
               <Button
@@ -3537,7 +3599,7 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
         <ScrollableOverlay outerClassName="h-full min-w-0" className="h-full min-w-0">
           {!selectedFile ? (
             <div className="p-3 typography-ui text-muted-foreground">{t('filesView.editor.pickFileFromTree')}</div>
-          ) : (fileLoading || isImageAssetAuthLoading) ? (
+          ) : (fileLoading || isImageAssetAuthLoading || isPdfAssetAuthLoading) ? (
             suppressFileLoadingIndicator
               ? <div className="p-3" />
               : (
@@ -3548,15 +3610,17 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
               )
           ) : fileError ? (
             <div className="p-3 typography-ui text-[color:var(--status-error)]">{fileError}</div>
-          ) : isSelectedImage ? (
-            <div className="flex h-full items-center justify-center p-3">
-              <img
-                src={imageSrc}
-                alt={selectedFile?.name ?? t('filesView.editor.imageAltFallback')}
-                className="max-w-full max-h-[70vh] object-contain rounded-md border border-border/30 bg-primary/10"
-              />
-            </div>
-          ) : selectedFile && isDrawio && drawioViewMode === 'preview' ? (
+          ) : isSelectedImage ? (
+            <div className="flex h-full items-center justify-center p-3">
+              <img
+                src={imageSrc}
+                alt={selectedFile?.name ?? t('filesView.editor.imageAltFallback')}
+                className="max-w-full max-h-[70vh] object-contain rounded-md border border-border/30 bg-primary/10"
+              />
+            </div>
+          ) : isSelectedPdf ? (
+            renderPdfPreview(selectedFile)
+          ) : selectedFile && isDrawio && drawioViewMode === 'preview' ? (
             <div className="h-full overflow-hidden" style={{ minHeight: '400px' }}>
               <DiagramEditor
                 key={`${selectedFile.path}:${drawioRemountNonce}`}
@@ -3881,7 +3945,7 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
           {renderFloatingFileControls({ exitFullscreenOnly: true })}
         </div>
         <ScrollableOverlay outerClassName="h-full min-w-0" className="h-full min-w-0">
-          {(fileLoading || isImageAssetAuthLoading) ? (
+          {(fileLoading || isImageAssetAuthLoading || isPdfAssetAuthLoading) ? (
             suppressFileLoadingIndicator
               ? <div className="p-4" />
               : (
@@ -3892,15 +3956,17 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
               )
           ) : fileError ? (
             <div className="p-4 typography-ui text-[color:var(--status-error)]">{fileError}</div>
-          ) : isSelectedImage ? (
-            <div className="flex h-full items-center justify-center p-4">
-              <img
-                src={imageSrc}
-                alt={selectedFile.name}
-                className="max-w-full max-h-full object-contain rounded-md border border-border/30 bg-primary/10"
-              />
-            </div>
-          ) : isMarkdown && getMdViewMode() === 'preview' ? (
+          ) : isSelectedImage ? (
+            <div className="flex h-full items-center justify-center p-4">
+              <img
+                src={imageSrc}
+                alt={selectedFile.name}
+                className="max-w-full max-h-full object-contain rounded-md border border-border/30 bg-primary/10"
+              />
+            </div>
+          ) : isSelectedPdf ? (
+            renderPdfPreview(selectedFile)
+          ) : isMarkdown && getMdViewMode() === 'preview' ? (
             <div className="h-full overflow-auto p-4">
               {fileContent.length > 500 * 1024 && (
                   <div className="mb-3 rounded-md border border-status-warning/20 bg-status-warning/10 px-3 py-2 text-sm text-status-warning">
diff --git a/packages/ui/src/lib/toolHelpers.ts b/packages/ui/src/lib/toolHelpers.ts
index 3e67070c..79f77eff 100644
--- a/packages/ui/src/lib/toolHelpers.ts
+++ b/packages/ui/src/lib/toolHelpers.ts
@@ -693,6 +693,11 @@ export function isImageFile(filePath: string): boolean {
   return IMAGE_EXTENSIONS.includes(ext || '');
 }
 
+export function isPdfFile(filePath: string): boolean {
+  const ext = filePath.split('.').pop()?.toLowerCase();
+  return ext === 'pdf';
+}
+
 export function getImageMimeType(filePath: string): string {
   const ext = filePath.split('.').pop()?.toLowerCase();
   const mimeMap: Record<string, string> = {
diff --git a/packages/web/server/lib/fs/routes.js b/packages/web/server/lib/fs/routes.js
index c9a909a3..d2d61a5b 100644
--- a/packages/web/server/lib/fs/routes.js
+++ b/packages/web/server/lib/fs/routes.js
@@ -840,6 +840,7 @@ export const registerFsRoutes = (app, dependencies) => {
         '.ico': 'image/x-icon',
         '.bmp': 'image/bmp',
         '.avif': 'image/avif',
+        '.pdf': 'application/pdf',
       };
       const mimeType = mimeMap[ext] || 'application/octet-stream';