The format prop reuses Timestamp's format vocabulary to control how the committed value is displayed: date, date_long (default), date_weekday, and system_date, or a function for a fully custom string. Formatting applies only to the committed value, never to text the user is actively typing.
pnpm dlx shadcn@latest add "https://astryx.atmeta.com/shadcn/example-date-input-formats.json"