/** Parses an ISO `YYYY-MM-DD` string into a local-midnight `Date`, or `null` when invalid. */
export declare function isoToDate(iso: string | null | undefined): Date | null;
/** Serializes a local calendar date to ISO `YYYY-MM-DD`. */
export declare function dateToIso(date: Date): string;
/** Returns true when `iso` falls within optional `min` / `max` bounds (inclusive). */
export declare function isIsoInRange(iso: string, min?: string, max?: string): boolean;