Sound Belongs to the User
MUST: Ship an explicit mute toggle in settings plus a volume control independent of system volume, and default the volume subtle (`0.3`) — never loud, never autoplaying. The OS mixer silences everything, not just you, so "turn your machine down" is not an off switch.
Ship an explicit mute toggle, an independent volume control, and a subtle default
Bad
Good
Why it matters
Cherry-picked from Raphael Salaja's sounds-on-the-web skill, merging three of its rules (`a11y-toggle-setting`, `a11y-volume-control`, `impl-default-subtle`). A sound provider with no off switch treats audio as a property of the product rather than a property of the session, and the user's only recourse is the OS mixer — which silences everything, not just you.
Three controls fix it. An explicit toggle, because "turn down my whole machine" is not an answer to "this app is noisy". An in-app volume independent of system volume, because the right level for a notification chime and the right level for a video are different numbers, and only the user knows what else is playing. And a subtle default: the upstream number is 0.3, chosen so that the first sound a user hears is never the loudest thing they have heard today.
Defaulting to full volume converts a nice touch into an ambush, and an ambushed user mutes the tab permanently — which loses you the channel entirely.