diff --git a/src/components/app-shell.tsx b/src/components/app-shell.tsx
index d72569f..349da7f 100644
--- a/src/components/app-shell.tsx
+++ b/src/components/app-shell.tsx
@@ -46,10 +46,60 @@ const NAV: NavItem[] = [
   { to: "/settings", label: "Settings", icon: Settings, adminOnly: true },
 ];
 
+function useUnreadMessagesCount() {
+  const { user } = useAuth();
+  const uid = user?.id;
+  const [count, setCount] = useState(0);
+
+  const refresh = useCallback(async () => {
+    if (!uid) {
+      setCount(0);
+      return;
+    }
+    const { data: mems } = await supabase
+      .from("conversation_members")
+      .select("conversation_id, last_read_at")
+      .eq("user_id", uid);
+    if (!mems || mems.length === 0) {
+      setCount(0);
+      return;
+    }
+    let total = 0;
+    await Promise.all(
+      mems.map(async (m) => {
+        const { count: c } = await supabase
+          .from("messages")
+          .select("id", { count: "exact", head: true })
+          .eq("conversation_id", m.conversation_id)
+          .gt("created_at", m.last_read_at)
+          .neq("sender_id", uid);
+        total += c ?? 0;
+      }),
+    );
+    setCount(total);
+  }, [uid]);
+
+  useEffect(() => {
+    refresh();
+    if (!uid) return;
+    const ch = supabase
+      .channel("sidebar-unread")
+      .on("postgres_changes", { event: "*", schema: "public", table: "messages" }, () => refresh())
+      .on("postgres_changes", { event: "UPDATE", schema: "public", table: "conversation_members", filter: `user_id=eq.${uid}` }, () => refresh())
+      .subscribe();
+    return () => {
+      supabase.removeChannel(ch);
+    };
+  }, [uid, refresh]);
+
+  return count;
+}
+
 export function AppShell({ children }: { children: ReactNode }) {
   const { user, signOut, isAdmin, roles } = useAuth();
   const location = useLocation();
   const navigate = useNavigate();
+  const unreadMessages = useUnreadMessagesCount();
 
   const handleSignOut = async () => {
     await signOut();
@@ -79,6 +129,7 @@ export function AppShell({ children }: { children: ReactNode }) {
                 ? location.pathname === "/"
                 : location.pathname.startsWith(item.to);
             const Icon = item.icon;
+            const showBadge = item.to === "/messages" && unreadMessages > 0;
             return (
               <Link
                 key={item.to}
@@ -91,7 +142,12 @@ export function AppShell({ children }: { children: ReactNode }) {
                 )}
               >
                 <Icon className="h-4 w-4" />
-                {item.label}
+                <span className="flex-1">{item.label}</span>
+                {showBadge && (
+                  <Badge variant="destructive" className="h-5 px-1.5 text-[10px]">
+                    {unreadMessages}
+                  </Badge>
+                )}
               </Link>
             );
           })}