diff --git a/TopManager/TopManagerApp.swift b/TopManager/TopManagerApp.swift
index 69d9bbf..214b72c 100644
--- a/TopManager/TopManagerApp.swift
+++ b/TopManager/TopManagerApp.swift
@@ -1,8 +1,20 @@
 import SwiftUI
+import UserNotifications
+
+/// Flushes persisted metrics history when the app is quit, and lets alert banners
+/// appear even while TopManager is the foreground app (macOS suppresses an app's
+/// own notifications in the foreground unless the delegate opts in).
+final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCenterDelegate {
+    func applicationDidFinishLaunching(_ notification: Notification) {
+        UNUserNotificationCenter.current().delegate = self
+    }
+
+    func userNotificationCenter(_ center: UNUserNotificationCenter,
+                                willPresent notification: UNNotification,
+                                withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
+        completionHandler([.banner, .sound, .list])
+    }
 
-/// Flushes persisted metrics history when the app is quit so history isn't lost
-/// between the throttled background saves.
-final class AppDelegate: NSObject, NSApplicationDelegate {
     func applicationWillTerminate(_ notification: Notification) {
         MetricsStore.shared.flush()
     }