How to actually mute toast sounds in Decky Loader plugins

decky-toast-sound-muting.md

How to Actually Mute Toast Sounds in Decky Loader Plugins

playSound: false does not work. Here is why, and what does.

The Problem

Decky Loader's toaster.toast() accepts playSound?: boolean and sound?: number, but neither field silences the sound in practice.

What Decky actually sends to Steam

Decky's internal toast() function builds an info object like this:

const info = {
  showToast: toast.showToast,
  sound: toast.sound,       // your sound value IS forwarded
  eFeature: 0,
  toastDurationMS: ...,
  bCritical: toast.critical,
  fnTray,
  // playSound is NOT included here
};
window.NotificationStore.ProcessNotification(info, toastData, ToastType.New);

playSound is silently dropped.

Where the sound is actually played

When Steam renders the toast, the React component runs:

useEffect(() => { e && NotificationStore.PlayNotificationSound(e) }, [e])

PlayNotificationSound(toastData) does:

const r = W[toastData.eType];   // looks up Steam's hardcoded type map -- NOT your info object
const soundId = ChooseSound(r, toastData);
if (soundId) PlayNavSound(soundId);

ChooseSound logic:

const play = e.playSound ?? !!e.sound;
if ((clientSettings.play_sound_on_toast || e.bCritical) && play) return e.sound;
return null;

For the Decky default eType: 31 ("General"), W[31] has sound: ToastMisc and no playSound, so play = true -- sound always plays, regardless of what you put in your toast args.

The Fix

Pass eType: 40 when muting. W[40] ("Steam Input Action Set") has playSound: false:

// ChooseSound(W[40], ...) -> play = false -> returns null -> no sound

Decky still renders your toast normally because it uses its own info object (with showToast: true, your title/body). The eType only affects the PlayNotificationSound lookup.

In practice (TypeScript)

const soundOn = getSetting('toast-sound-enabled', true);

deckyToaster.toast({
  title: 'My Plugin',
  body: 'Hello!',
  playSound: soundOn,
  // sound:0 covers the info.sound path; eType:40 covers the W[eType] path
  ...(soundOn ? {} : { sound: 0, eType: 40 }),
});

Why Two Fields?

• sound: 0 -- silences the ChooseSound(info, ...) call inside ProcessNotification (where info is used).
• eType: 40 -- silences PlayNotificationSound(toastData) called by the toast React component (where W[eType] is used).

Both code paths are hit when a toast is shown; you need both to be safe.

Verified Against

• Decky Loader: checked against /tmp/_MEI*/decky_loader/static/chunk-*.js
• Steam UI: checked against /home/deck/.steam/root/steamui/chunk~2dcc5aaf7.js
• SteamOS stable (April 2025)

eType Reference (Silent Options)

eType	Steam Name	playSound	showToast	Notes
40	Steam Input Action Set	false	true	Best choice -- toast shows, no sound
41	Remote Client Connection	false	false	Toast hidden in W but Decky info overrides
43	Streaming Client Connection	false	false	Same
57	GRUM	false	false	bEnableInReducedUI: false