/**
 * Date formatting shared by the accessor expression language and built-in
 * widgets. The public surface is intentionally small and deterministic:
 * numeric values are epoch milliseconds, the default zone is UTC, and the
 * locale is fixed so authored maps and snapshots do not vary by viewer.
 */
export declare const DATE_FORMAT_STYLES: readonly ["date", "datetime", "time", "iso"];
export type DateFormatStyle = (typeof DATE_FORMAT_STYLES)[number];
export declare function isDateFormatStyle(value: string): value is DateFormatStyle;
/** `local` is the explicit opt-in to the viewer's local time zone. */
export declare function isValidTimeZone(value: string): boolean;
/**
 * Format an epoch-millisecond number or ISO date string.
 *
 * Invalid values, styles, and time zones return an empty string so one bad
 * datum cannot crash a deck.gl accessor or widget reconciliation pass.
 */
export declare function formatDate(value: unknown, style?: DateFormatStyle | string, timeZone?: string): string;