Toast

A confirmation after an action: a small plate with a lamp and one factual sentence, read out politely, gone in 3.6 seconds.

Press a key: the plate rises bottom right and leaves by itself.

• Toasts go into one role="status" region with aria-live="polite", so they are read after the current sentence.
• They leave on their own: never put a decision or an error that needs action in one. Use a dialog, or a hint on the field.