Skip default completion sound when playback is disabled

- treat only `src: null` as an explicit no-play signal
- add test to ensure disabled playback does not trigger default audio

Author: ThallesP

apps/web/src/agentCompletionNotifications.test.ts

@@ -416,4 +416,27 @@ describe("agent completion notifications", () => {
       }),
     ).resolves.toBeNull();
   });
+
+  it("does not play the default sound when configured playback is disabled", async () => {
+    const playMock = vi.fn(async () => undefined);
+
+    class FakeAudio {
+      currentTime = 0;
+      preload = "";
+      play = playMock;
+      constructor(public readonly src: string) {}
+    }
+
+    vi.stubGlobal("Audio", FakeAudio);
+
+    const { playConfiguredCompletionSound } = await import("./agentCompletionNotifications");
+
+    await playConfiguredCompletionSound({
+      enableCompletionSound: false,
+      notificationSoundSelection: "default",
+      notificationCustomSoundId: "",
+    });
+
+    expect(playMock).not.toHaveBeenCalled();
+  });
 });

apps/web/src/agentCompletionNotifications.ts

@@ -270,10 +270,10 @@ export function collectNewlySettledTurns(
 
 export async function playCompletionSound(options: PlayCompletionSoundOptions = {}): Promise<void> {
   try {
-    const src = options.src ?? "/sounds/agent-finished.mp3";
-    if (!src) {
+    if (options.src === null) {
       return;
     }
+    const src = options.src ?? "/sounds/agent-finished.mp3";
     if (!completionSound || completionSoundSrc !== src) {
       completionSound = createCompletionSound(src);
       completionSoundSrc = src;