diff --git a/src/frontend/src/components/NotificationCenter.tsx b/src/frontend/src/components/NotificationCenter.tsx
index 3ccc4b2..115f45f 100644
--- a/src/frontend/src/components/NotificationCenter.tsx
+++ b/src/frontend/src/components/NotificationCenter.tsx
@@ -66,15 +66,18 @@ export default function NotificationCenter({ onClose }: { onClose: () => void })
           'agent_completed', 'agent_spawned',
         ];
         if (importantTypes.includes(e.type || data.event_type)) {
-          setSseEvents(prev => [{
-            id: data.id || `sse-${Date.now()}`,
-            type: (e.type === 'task_failed' ? 'error' : e.type === 'task_completed' ? 'success' : 'info') as NotifItem['type'],
-            title: data.title || data.event_type || e.type,
-            message: data.detail || JSON.stringify(data).slice(0, 100),
-            time: data.timestamp || new Date().toISOString(),
-            read: false,
-            source: 'event' as const,
-          }, ...prev].slice(0, 20)]);
+          setSseEvents(prev => {
+            const item: NotifItem = {
+              id: data.id || `sse-${Date.now()}`,
+              type: e.type === 'task_failed' ? 'error' : e.type === 'task_completed' ? 'success' : 'info',
+              title: data.title || data.event_type || e.type || 'Event',
+              message: data.detail || JSON.stringify(data).slice(0, 100),
+              time: data.timestamp || new Date().toISOString(),
+              read: false,
+              source: 'event',
+            };
+            return [item, ...prev].slice(0, 20);
+          });
         }
       } catch { /* ignore parse errors */ }
     };