diff --git a/src/components/layout/AppShell.tsx b/src/components/layout/AppShell.tsx
index 055ff86..81537d3 100644
--- a/src/components/layout/AppShell.tsx
+++ b/src/components/layout/AppShell.tsx
@@ -115,12 +115,11 @@ export function AppShell({ children }: { children: React.ReactNode }) {
   }, []);
 
   // Auto-open panel on chat detail routes, close on others
+  // Also close doc preview when navigating away or switching sessions
   useEffect(() => {
     setPanelOpenRaw(isChatDetailRoute);
-    if (!isChatDetailRoute) {
-      setPreviewFileRaw(null);
-    }
-  }, [isChatDetailRoute]);
+    setPreviewFileRaw(null);
+  }, [isChatDetailRoute, pathname]);
 
   const setPanelOpen = useCallback((open: boolean) => {
     setPanelOpenRaw(open);
diff --git a/src/components/layout/DocPreview.tsx b/src/components/layout/DocPreview.tsx
index 06cea04..c2a6503 100644
--- a/src/components/layout/DocPreview.tsx
+++ b/src/components/layout/DocPreview.tsx
@@ -93,8 +93,9 @@ export function DocPreview({
     };
   }, [filePath]);
 
-  const handleCopyPath = async () => {
-    await navigator.clipboard.writeText(filePath);
+  const handleCopyContent = async () => {
+    const text = preview?.content || filePath;
+    await navigator.clipboard.writeText(text);
     setCopied(true);
     setTimeout(() => setCopied(false), 2000);
   };
@@ -126,13 +127,13 @@ export function DocPreview({
           <ViewModeToggle value={viewMode} onChange={onViewModeChange} />
         )}
 
-        <Button variant="ghost" size="icon-sm" onClick={handleCopyPath}>
+        <Button variant="ghost" size="icon-sm" onClick={handleCopyContent}>
           {copied ? (
             <HugeiconsIcon icon={Tick01Icon} className="h-3.5 w-3.5 text-green-500" />
           ) : (
             <HugeiconsIcon icon={Copy01Icon} className="h-3.5 w-3.5" />
           )}
-          <span className="sr-only">Copy path</span>
+          <span className="sr-only">Copy content</span>
         </Button>
 
         <Button variant="ghost" size="icon-sm" onClick={onClose}>
diff --git a/src/components/layout/RightPanel.tsx b/src/components/layout/RightPanel.tsx
index e3f6586..849a3b5 100644
--- a/src/components/layout/RightPanel.tsx
+++ b/src/components/layout/RightPanel.tsx
@@ -67,6 +67,19 @@ export function RightPanel({ width }: RightPanelProps) {
   }, [handleSaveName]);
 
   const handleFileSelect = useCallback((path: string) => {
+    // Only open preview for text-based files, skip images/videos/binaries
+    const ext = path.split(".").pop()?.toLowerCase() || "";
+    const NON_PREVIEWABLE = new Set([
+      "png", "jpg", "jpeg", "gif", "bmp", "ico", "webp", "svg", "avif",
+      "mp4", "mov", "avi", "mkv", "webm", "flv", "wmv",
+      "mp3", "wav", "ogg", "flac", "aac", "wma",
+      "zip", "tar", "gz", "rar", "7z", "bz2",
+      "pdf", "doc", "docx", "xls", "xlsx", "ppt", "pptx",
+      "exe", "dll", "so", "dylib", "bin", "dmg", "iso",
+      "woff", "woff2", "ttf", "otf", "eot",
+    ]);
+    if (NON_PREVIEWABLE.has(ext)) return;
+
     // Toggle: clicking the same file closes the preview
     if (previewFile === path) {
       setPreviewFile(null);