diff --git a/packages/cli/__tests__/lib/startup-notifier-defaults.test.ts b/packages/cli/__tests__/lib/startup-notifier-defaults.test.ts
index 4aa51b959..240157ebe 100644
--- a/packages/cli/__tests__/lib/startup-notifier-defaults.test.ts
+++ b/packages/cli/__tests__/lib/startup-notifier-defaults.test.ts
@@ -159,6 +159,41 @@ describe("startup notifier defaults", () => {
     expect(parsed.notificationRouting?.urgent).toEqual(["desktop", "dashboard"]);
   });
 
+  it("preserves defaults.notifiers fallback semantics when writing startup routes", () => {
+    writeFileSync(
+      configPath,
+      [
+        "port: 3000",
+        "defaults:",
+        "  notifiers:",
+        "    - slack",
+        "notifiers:",
+        "  slack:",
+        "    plugin: slack",
+        "    webhookUrl: https://hooks.slack.com/services/T/B/C",
+        "projects: {}",
+        "",
+      ].join("\n"),
+    );
+
+    expect(
+      ensureStartupNotifierDefaults({
+        configPath,
+        dashboardUrl: "http://localhost:3000",
+        desktopMode: "enable",
+      }),
+    ).toBe(true);
+
+    const parsed = readConfig();
+    expect(parsed.defaults?.notifiers).toEqual(["slack"]);
+    expect(parsed.notificationRouting).toEqual({
+      urgent: ["slack", "desktop", "dashboard"],
+      action: ["slack", "dashboard"],
+      warning: ["slack", "dashboard"],
+      info: ["slack", "dashboard"],
+    });
+  });
+
   it("preserves configured manual opt-in notifiers while removing only implicit manual defaults", () => {
     writeFileSync(
       configPath,
diff --git a/packages/cli/src/lib/startup-notifier-defaults.ts b/packages/cli/src/lib/startup-notifier-defaults.ts
index cdc299f27..291f0b6d9 100644
--- a/packages/cli/src/lib/startup-notifier-defaults.ts
+++ b/packages/cli/src/lib/startup-notifier-defaults.ts
@@ -44,6 +44,10 @@ function arraysEqual(left: string[], right: string[]): boolean {
   return left.length === right.length && left.every((value, index) => value === right[index]);
 }
 
+function hasOwn(record: Record<string, unknown>, key: string): boolean {
+  return Object.prototype.hasOwnProperty.call(record, key);
+}
+
 function hasNotifierConfig(notifiers: Record<string, unknown>, notifierName: string): boolean {
   return isRecord(notifiers[notifierName]);
 }
@@ -227,7 +231,12 @@ export function ensureStartupNotifierDefaults(options: StartupNotifierDefaultsOp
   const shouldRemoveDefaultDesktopRouting = desktopMode === "disable-default" && !desktopConfigured;
 
   for (const priority of NOTIFICATION_PRIORITIES) {
-    const existingRoute = sanitizeNotifierReferences(notifiers, routing[priority]);
+    const hasExplicitRoute = hasOwn(routing, priority);
+    const existingRoute = sanitizeNotifierReferences(
+      notifiers,
+      hasExplicitRoute ? routing[priority] : defaults["notifiers"],
+    );
+    const previousRoute = hasExplicitRoute ? asStringArray(routing[priority]) : existingRoute;
     let nextRoute = existingRoute;
 
     if (shouldRemoveDefaultDesktopRouting) {
@@ -245,7 +254,7 @@ export function ensureStartupNotifierDefaults(options: StartupNotifierDefaultsOp
     }
 
     nextRoute = unique(nextRoute);
-    if (!arraysEqual(asStringArray(routing[priority]), nextRoute)) {
+    if (!arraysEqual(previousRoute, nextRoute)) {
       routing[priority] = nextRoute;
       changed = true;
     }
diff --git a/packages/plugins/notifier-desktop/src/index.test.ts b/packages/plugins/notifier-desktop/src/index.test.ts
index 1f7755c41..21cba3776 100644
--- a/packages/plugins/notifier-desktop/src/index.test.ts
+++ b/packages/plugins/notifier-desktop/src/index.test.ts
@@ -483,6 +483,18 @@ describe("notifier-desktop", () => {
       expect(mockExecFile.mock.calls[0][0]).toBe("notify-send");
     });
 
+    it("keeps action labels on non-macOS even when backend is ao-app", async () => {
+      mockPlatform.mockReturnValue("linux");
+      setProcessPlatform("linux");
+      const notifier = create({ backend: "ao-app", dashboardUrl: "http://localhost:3000" });
+      const actions: NotifyAction[] = [{ label: "Open PR", url: "https://example.com/pr/1" }];
+      await notifier.notifyWithActions!(makeEvent(), actions);
+
+      expect(mockExecFile.mock.calls[0][0]).toBe("notify-send");
+      const args = mockExecFile.mock.calls[0][1] as string[];
+      expect(args.join("\n")).toContain("Open PR");
+    });
+
     it("uses terminal-notifier for notifyWithActions too", async () => {
       const notifier = create({ dashboardUrl: "http://localhost:3000" });
       const actions: NotifyAction[] = [{ label: "View", url: "https://example.com" }];
diff --git a/packages/plugins/notifier-desktop/src/index.ts b/packages/plugins/notifier-desktop/src/index.ts
index 47bee1d25..afce79928 100644
--- a/packages/plugins/notifier-desktop/src/index.ts
+++ b/packages/plugins/notifier-desktop/src/index.ts
@@ -388,6 +388,10 @@ function detectTerminalNotifier(): boolean {
   }
 }
 
+function usesAoNotifierNativeActions(backend: DesktopBackend, appPath: string): boolean {
+  return isMac() && (backend === "ao-app" || (backend === "auto" && detectAoNotifierApp(appPath)));
+}
+
 /**
  * Send a desktop notification using terminal-notifier / osascript (macOS) or
  * notify-send (Linux). Falls back gracefully if neither is available.
@@ -568,10 +572,9 @@ export function create(config?: Record<string, unknown>): Notifier {
     async notifyWithActions(event: OrchestratorEvent, actions: NotifyAction[]): Promise<void> {
       const nativeActions = nativeActionPayloads(actions, dashboardUrl);
       const content = formatContent(event, actions, {
-        hiddenActionIndexes:
-          backend === "ao-app" || (backend === "auto" && detectAoNotifierApp(appPath))
-            ? nativeActionIndexes(actions, dashboardUrl)
-            : undefined,
+        hiddenActionIndexes: usesAoNotifierNativeActions(backend, appPath)
+          ? nativeActionIndexes(actions, dashboardUrl)
+          : undefined,
       });
       const fallbackContent = formatContent(event, actions);
       const sound = shouldPlaySound(event.priority, soundEnabled);