diff --git a/src/components/cases/documents-tab.tsx b/src/components/cases/documents-tab.tsx
index 9eaa68e..544ec93 100644
--- a/src/components/cases/documents-tab.tsx
+++ b/src/components/cases/documents-tab.tsx
@@ -380,6 +380,80 @@ export function CaseDocumentsTab({ caseId }: { caseId: string }) {
           </CardContent>
         </Card>
       </div>
+
+      <Dialog open={!!previewDoc} onOpenChange={(o) => !o && closePreview()}>
+        <DialogContent className="max-w-5xl w-[95vw] h-[85vh] flex flex-col p-0 gap-0">
+          <DialogHeader className="px-4 py-3 border-b flex-row items-center justify-between space-y-0">
+            <DialogTitle className="truncate pr-4">{previewDoc?.name}</DialogTitle>
+            {previewUrl && (
+              <div className="flex items-center gap-1 mr-6">
+                <Button variant="ghost" size="sm" onClick={() => window.open(previewUrl, "_blank")}>
+                  <ExternalLink className="h-4 w-4 mr-1.5" /> Open
+                </Button>
+                <Button variant="ghost" size="sm" onClick={() => previewDoc && download(previewDoc)}>
+                  <Download className="h-4 w-4 mr-1.5" /> Download
+                </Button>
+              </div>
+            )}
+          </DialogHeader>
+          <div className="flex-1 min-h-0 bg-muted/30">
+            {previewLoading ? (
+              <div className="h-full flex items-center justify-center text-muted-foreground">
+                <Loader2 className="h-5 w-5 animate-spin mr-2" /> Loading preview…
+              </div>
+            ) : previewUrl && previewDoc ? (
+              <PreviewBody url={previewUrl} doc={previewDoc} />
+            ) : null}
+          </div>
+        </DialogContent>
+      </Dialog>
+    </div>
+  );
+}
+
+function PreviewBody({ url, doc }: { url: string; doc: any }) {
+  const mime = (doc.mime_type || "").toLowerCase();
+  const name = (doc.name || "").toLowerCase();
+  const isImage = mime.startsWith("image/") || /\.(png|jpe?g|gif|webp|svg|bmp)$/i.test(name);
+  const isPdf = mime === "application/pdf" || name.endsWith(".pdf");
+  const isText =
+    mime.startsWith("text/") ||
+    /\.(txt|md|csv|json|log|xml|yml|yaml)$/i.test(name);
+  const isAudio = mime.startsWith("audio/") || /\.(mp3|wav|m4a|ogg)$/i.test(name);
+  const isVideo = mime.startsWith("video/") || /\.(mp4|webm|mov)$/i.test(name);
+
+  if (isImage) {
+    return (
+      <div className="h-full w-full flex items-center justify-center overflow-auto p-4">
+        <img src={url} alt={doc.name} className="max-h-full max-w-full object-contain" />
+      </div>
+    );
+  }
+  if (isPdf || isText) {
+    return <iframe src={url} title={doc.name} className="h-full w-full border-0 bg-white" />;
+  }
+  if (isAudio) {
+    return (
+      <div className="h-full flex items-center justify-center p-4">
+        <audio controls src={url} className="w-full max-w-xl" />
+      </div>
+    );
+  }
+  if (isVideo) {
+    return (
+      <div className="h-full flex items-center justify-center p-4 bg-black">
+        <video controls src={url} className="max-h-full max-w-full" />
+      </div>
+    );
+  }
+  return (
+    <div className="h-full flex flex-col items-center justify-center text-center p-8 text-muted-foreground">
+      <FileText className="h-10 w-10 mb-3 opacity-60" />
+      <p className="mb-1">No inline preview available for this file type.</p>
+      <p className="text-xs mb-4">{doc.mime_type || "Unknown type"}</p>
+      <Button onClick={() => window.open(url, "_blank")}>
+        <ExternalLink className="h-4 w-4 mr-1.5" /> Open in new tab
+      </Button>
     </div>
   );
 }