export declare function unixSecondsFromDate(date: Date): number;
/**
 * Build Info-ZIP "Extended Timestamp" extra field (0x5455).
 * We write only mtime (UTC, Unix seconds) to minimize size.
 *
 * Layout:
 * - Header ID: 2 bytes (0x5455)
 * - Data size: 2 bytes
 * - Flags: 1 byte (bit0 = mtime)
 * - mtime: 4 bytes (Unix seconds)
 */
export declare function buildExtendedTimestampExtraFieldFromUnixSeconds(unixSeconds: number): Uint8Array;
export declare function buildExtendedTimestampExtraFieldFromDate(date: Date): Uint8Array;
/**
 * Parse Info-ZIP "Extended Timestamp" extra field (0x5455) and return mtime.
 * Returns Unix seconds (UTC) if present.
 */
export declare function parseExtendedTimestampMtimeUnixSeconds(extraField: Uint8Array): number | undefined;
