/**
 * Formats a DocumentVersion createdAt date string for display in the editor UI.
 * Returns an empty string for invalid/missing dates (safe to use as a falsy guard).
 */
export declare function formatVersionDate(dateString: string): string;
/**
 * Returns a human-readable day-group label for a version timestamp:
 * 'Today', 'Yesterday', or a short date like 'Jul 15'.
 *
 * Day boundaries use local browser time. API timestamps are UTC ISO strings,
 * so users near midnight in timezones ahead of UTC may see a version group
 * under a different day than expected — this is intentional local-time behaviour.
 */
export declare function dayLabel(isoString: string): string;