/**
 * Convert integer card codes to string array
 */
export declare function cardCodesToStrings(codes: readonly number[]): string[];
/**
 * Convert string card array to integer codes
 * Filters out null (masked) cards
 */
export declare function cardStringsToCards(cards: ReadonlyArray<string | null>): number[];
/**
 * Validate card string format
 */
export declare function isValidCard(card: string): boolean;