feat(notifications): scale completion sound speed with task length

apps/code/src/renderer/desktop-services.ts

@@ -202,6 +202,7 @@ container
         dockBounceNotifications: s.dockBounceNotifications,
         completionSound: s.completionSound,
         completionVolume: s.completionVolume,
+        scaleSoundWithTaskLength: s.scaleSoundWithTaskLength,
         customSounds: s.customSounds,
       };
     },

packages/core/src/sessions/cloudTaskUpdateNotifications.test.ts

@@ -178,6 +178,7 @@ describe("cloud task update notifications", () => {
       "Cloud Task",
       "end_turn",
       TASK_ID,
+      undefined,
     );
     expect(harness.markActivity).toHaveBeenCalledTimes(1);
   });

packages/core/src/sessions/sessionService.ts

@@ -1550,6 +1550,9 @@ export class SessionService {
                 session.taskTitle,
                 "end_turn",
                 session.taskId,
+                session.promptStartedAt
+                  ? acpMsg.ts - session.promptStartedAt
+                  : undefined,
               );
             }
             this.d.taskViewedApi.markActivity(session.taskId);
@@ -1671,6 +1674,9 @@ export class SessionService {
           session.taskTitle,
           stopReason,
           session.taskId,
+          session.promptStartedAt
+            ? acpMsg.ts - session.promptStartedAt
+            : undefined,
         );
       }
 

packages/ui/src/features/notifications/identifiers.ts

@@ -10,6 +10,7 @@ export interface NotificationSettings {
   dockBounceNotifications: boolean;
   completionSound: CompletionSound;
   completionVolume: number;
+  scaleSoundWithTaskLength: boolean;
   customSounds: CustomSound[];
 }
 

packages/ui/src/features/notifications/notifications.test.ts

@@ -51,6 +51,7 @@ function makeBus(overrides?: {
     dockBounceNotifications: true,
     completionSound: "meep",
     completionVolume: 80,
+    scaleSoundWithTaskLength: false,
     customSounds: [],
     ...overrides?.settings,
   };
@@ -183,4 +184,22 @@ describe("sound", () => {
     bus.notifyPromptComplete("My task", "end_turn", TASK_ID);
     expect(play).toHaveBeenCalledTimes(1);
   });
+
+  it.each([
+    [
+      "scaling off, with duration",
+      false,
+      (10 * 60 * 1000) as number | undefined,
+      1,
+    ],
+    ["scaling on, quick task (<30s) → 3×", true, 10 * 1000, 3],
+    ["scaling on, no duration → 1×", true, undefined, 1],
+  ])("%s", (_label, scaleSoundWithTaskLength, durationMs, expectedRate) => {
+    const { bus, play } = makeBus({
+      hasFocus: false,
+      settings: { scaleSoundWithTaskLength },
+    });
+    bus.notifyPromptComplete("My task", "end_turn", TASK_ID, durationMs);
+    expect(play).toHaveBeenCalledWith("meep", 80, [], expectedRate);
+  });
 });

packages/ui/src/features/notifications/notifications.ts

@@ -5,7 +5,11 @@ import {
 } from "@posthog/platform/notifications";
 import { toast } from "@posthog/ui/primitives/toast";
 import { openNotificationTarget } from "@posthog/ui/router/navigationBridge";
-import { playCompletionSound, resolveSoundUrl } from "@posthog/ui/utils/sounds";
+import {
+  playbackRateForTaskDuration,
+  playCompletionSound,
+  resolveSoundUrl,
+} from "@posthog/ui/utils/sounds";
 import { inject, injectable } from "inversify";
 import {
   ACTIVE_VIEW_PROVIDER,
@@ -34,6 +38,9 @@ export interface NotificationDescriptor {
     duration?: number;
   };
   silent?: boolean;
+  // How long the task took, in ms. When the user enables sound scaling, this
+  // drives the completion sound's playback rate (fast task -> faster/higher).
+  soundDurationMs?: number;
 }
 
 // The single channel every app notification flows through. Reads focus + the
@@ -61,12 +68,18 @@ export class NotificationBus {
     if (channel === "suppress") return;
 
     const settings = this.settings.get();
+    const playbackRate =
+      settings.scaleSoundWithTaskLength &&
+      descriptor.soundDurationMs !== undefined
+        ? playbackRateForTaskDuration(descriptor.soundDurationMs)
+        : 1;
     // Sound fires on both delivered tiers (toast + native), not on suppress —
     // matching the pre-bus behavior where any non-suppressed notification rang.
     playCompletionSound(
       settings.completionSound,
       settings.completionVolume,
       settings.customSounds,
+      playbackRate,
     );
 
     if (channel === "toast") {
@@ -100,12 +113,14 @@ export class NotificationBus {
     taskTitle: string,
     stopReason: string,
     taskId?: string,
+    durationMs?: number,
   ): void {
     if (stopReason !== "end_turn") return;
     this.notify({
       body: `"${this.truncateTitle(taskTitle)}" finished`,
       target: taskId ? { kind: "task", taskId } : undefined,
       toast: { level: "success" },
+      soundDurationMs: durationMs,
     });
   }
 

packages/ui/src/features/sessions/sessionServiceHost.ts

@@ -84,11 +84,12 @@ function buildSessionServiceDeps(): SessionServiceDeps {
         taskTitle,
         taskId,
       ),
-    notifyPromptComplete: (taskTitle, stopReason, taskId) =>
+    notifyPromptComplete: (taskTitle, stopReason, taskId, durationMs) =>
       resolveService(NotificationBus).notifyPromptComplete(
         taskTitle,
         stopReason,
         taskId,
+        durationMs,
       ),
     getIsOnline,
     fetchAuthState,

packages/ui/src/features/settings/sections/NotificationsSettings.tsx

@@ -40,12 +40,14 @@ export function NotificationsSettings() {
     dockBounceNotifications,
     completionSound,
     completionVolume,
+    scaleSoundWithTaskLength,
     customSounds,
     setDesktopNotifications,
     setDockBadgeNotifications,
     setDockBounceNotifications,
     setCompletionSound,
     setCompletionVolume,
+    setScaleSoundWithTaskLength,
     removeCustomSound,
     renameCustomSound,
   } = useSettingsStore();
@@ -117,19 +119,33 @@ export function NotificationsSettings() {
     [completionSound, setCompletionSound],
   );
 
+  const handleScaleSoundChange = useCallback(
+    (checked: boolean) => {
+      track(ANALYTICS_EVENTS.SETTING_CHANGED, {
+        setting_name: "scale_sound_with_task_length",
+        new_value: checked,
+        old_value: scaleSoundWithTaskLength,
+      });
+      setScaleSoundWithTaskLength(checked);
+    },
+    [scaleSoundWithTaskLength, setScaleSoundWithTaskLength],
+  );
+
   const resetToDefaults = useCallback(() => {
     setDesktopNotifications(NOTIFICATION_DEFAULTS.desktopNotifications);
     setDockBadgeNotifications(NOTIFICATION_DEFAULTS.dockBadgeNotifications);
     setDockBounceNotifications(NOTIFICATION_DEFAULTS.dockBounceNotifications);
     setCompletionSound(NOTIFICATION_DEFAULTS.completionSound);
     setCompletionVolume(NOTIFICATION_DEFAULTS.completionVolume);
+    setScaleSoundWithTaskLength(NOTIFICATION_DEFAULTS.scaleSoundWithTaskLength);
     toast.success("Notification settings reset to defaults");
   }, [
     setDesktopNotifications,
     setDockBadgeNotifications,
     setDockBounceNotifications,
     setCompletionSound,
     setCompletionVolume,
+    setScaleSoundWithTaskLength,
   ]);
 
   return (
@@ -270,7 +286,7 @@ export function NotificationsSettings() {
       />
 
       {completionSound !== "none" && (
-        <SettingRow label="Sound volume" noBorder>
+        <SettingRow label="Sound volume">
           <Flex align="center" gap="3">
             <Slider
               value={[completionVolume]}
@@ -288,6 +304,20 @@ export function NotificationsSettings() {
         </SettingRow>
       )}
 
+      {completionSound !== "none" && (
+        <SettingRow
+          label="Scale sound speed with task length"
+          description="Play the sound faster for quick tasks and slower for long ones"
+          noBorder
+        >
+          <Switch
+            checked={scaleSoundWithTaskLength}
+            onCheckedChange={handleScaleSoundChange}
+            size="1"
+          />
+        </SettingRow>
+      )}
+
       <NotificationTestHarness
         bus={bus}
         notifications={notifications}

packages/ui/src/features/settings/settingsStore.ts

@@ -113,12 +113,14 @@ interface SettingsStore {
   dockBounceNotifications: boolean;
   completionSound: CompletionSound;
   completionVolume: number;
+  scaleSoundWithTaskLength: boolean;
   customSounds: CustomSound[];
   setDesktopNotifications: (enabled: boolean) => void;
   setDockBadgeNotifications: (enabled: boolean) => void;
   setDockBounceNotifications: (enabled: boolean) => void;
   setCompletionSound: (sound: CompletionSound) => void;
   setCompletionVolume: (volume: number) => void;
+  setScaleSoundWithTaskLength: (enabled: boolean) => void;
   addCustomSound: (sound: CustomSound) => void;
   removeCustomSound: (id: string) => void;
   renameCustomSound: (id: string, name: string) => void;
@@ -187,6 +189,7 @@ export const NOTIFICATION_DEFAULTS = {
   dockBounceNotifications: false,
   completionSound: "none" as CompletionSound,
   completionVolume: 80,
+  scaleSoundWithTaskLength: false,
 };
 
 export const useSettingsStore = create<SettingsStore>()(
@@ -253,6 +256,8 @@ export const useSettingsStore = create<SettingsStore>()(
         set({ dockBounceNotifications: enabled }),
       setCompletionSound: (sound) => set({ completionSound: sound }),
       setCompletionVolume: (volume) => set({ completionVolume: volume }),
+      setScaleSoundWithTaskLength: (enabled) =>
+        set({ scaleSoundWithTaskLength: enabled }),
       addCustomSound: (sound) =>
         set((state) => ({ customSounds: [...state.customSounds, sound] })),
       removeCustomSound: (id) =>
@@ -381,6 +386,7 @@ export const useSettingsStore = create<SettingsStore>()(
         dockBounceNotifications: state.dockBounceNotifications,
         completionSound: state.completionSound,
         completionVolume: state.completionVolume,
+        scaleSoundWithTaskLength: state.scaleSoundWithTaskLength,
         customSounds: state.customSounds,
 
         // Composer / chat

packages/ui/src/utils/sounds.test.ts

@@ -3,7 +3,7 @@ import type {
   CustomSound,
 } from "@posthog/ui/features/settings/settingsStore";
 import { describe, expect, it } from "vitest";
-import { resolveSoundUrl } from "./sounds";
+import { playbackRateForTaskDuration, resolveSoundUrl } from "./sounds";
 
 const customs: CustomSound[] = [
   {
@@ -40,3 +40,23 @@ describe("resolveSoundUrl", () => {
     expect(resolveSoundUrl("custom:gone", customs)).toBeNull();
   });
 });
+
+describe("playbackRateForTaskDuration", () => {
+  it.each([
+    ["below the fast floor (10s)", 10 * 1000, 3],
+    ["at the fast floor (30s)", 30 * 1000, 3],
+    ["geometric mid of the fast ramp (60s)", 60 * 1000, Math.sqrt(3)],
+    ["normal band start (2min)", 2 * 60 * 1000, 1],
+    ["normal band end (4min)", 4 * 60 * 1000, 1],
+    [
+      "geometric mid of the slow ramp",
+      Math.sqrt(4 * 60 * 1000 * (30 * 60 * 1000)),
+      Math.sqrt(1 / 3),
+    ],
+    ["at the slow ceiling (30min)", 30 * 60 * 1000, 1 / 3],
+    ["beyond the slow ceiling (2h)", 2 * 60 * 60 * 1000, 1 / 3],
+    ["NaN (non-finite) → fast rate", Number.NaN, 3],
+  ])("%s → %f", (_label, durationMs, expected) => {
+    expect(playbackRateForTaskDuration(durationMs)).toBeCloseTo(expected, 5);
+  });
+});

packages/ui/src/utils/sounds.ts

@@ -37,6 +37,35 @@ const SOUND_URLS: Record<Exclude<BuiltInCompletionSound, "none">, string> = {
   icq: icqUrl,
 };
 
+const MIN_RATE = 1 / 3;
+const MAX_RATE = 3;
+const FAST_MS = 30 * 1000;
+const NORMAL_START_MS = 2 * 60 * 1000;
+const NORMAL_END_MS = 4 * 60 * 1000;
+const SLOW_MS = 30 * 60 * 1000;
+
+// Maps a task's duration to an audio playback rate so a quick task rings fast
+// (and high-pitched) while a long one drags slow (and low). Anchored at: <=30s
+// -> 3x, the 2-4min "normal" band -> 1x, >=30min -> 1/3x, with smooth
+// log-interpolation across the two ramps so the rate doesn't jump at the edges.
+export function playbackRateForTaskDuration(durationMs: number): number {
+  if (!Number.isFinite(durationMs) || durationMs <= FAST_MS) return MAX_RATE;
+  if (durationMs >= SLOW_MS) return MIN_RATE;
+  if (durationMs >= NORMAL_START_MS && durationMs <= NORMAL_END_MS) return 1;
+
+  if (durationMs < NORMAL_START_MS) {
+    const frac =
+      (Math.log(durationMs) - Math.log(FAST_MS)) /
+      (Math.log(NORMAL_START_MS) - Math.log(FAST_MS));
+    return MAX_RATE ** (1 - frac);
+  }
+
+  const frac =
+    (Math.log(durationMs) - Math.log(NORMAL_END_MS)) /
+    (Math.log(SLOW_MS) - Math.log(NORMAL_END_MS));
+  return MIN_RATE ** frac;
+}
+
 let currentAudio: HTMLAudioElement | null = null;
 
 // Resolves the playable URL for a completion sound: a bundled asset URL for the
@@ -59,6 +88,7 @@ export function playCompletionSound(
   sound: CompletionSound,
   volume = 80,
   customSounds: CustomSound[] = [],
+  playbackRate = 1,
 ): void {
   const url = resolveSoundUrl(sound, customSounds);
   if (!url) return;
@@ -70,6 +100,7 @@ export function playCompletionSound(
 
   const audio = new Audio(url);
   audio.volume = Math.max(0, Math.min(100, volume)) / 100;
+  audio.playbackRate = playbackRate;
   currentAudio = audio;
   audio.play().catch(() => {
     // Audio play can fail if user hasn't interacted with the page yet