export type CalendarSelectionMode = 'single' | 'multiple' | 'range';
export type IsoRange = {
    start: string;
    end: string;
};
export type RangeSelectionDraft = {
    anchor: string | null;
    hover: string | null;
};
export type DaySelectionAppearance = {
    isSelected: boolean;
    isRangeStart: boolean;
    isRangeEnd: boolean;
    isRangeMiddle: boolean;
};
/** Lexicographic compare for ISO `YYYY-MM-DD` strings. */
export declare function compareIso(a: string, b: string): number;
export declare function normalizeRange(start: string, end: string): IsoRange;
export declare function parseIsoRange(value: string | null | undefined): IsoRange | null;
export declare function serializeIsoRange(range: IsoRange | null): string;
export declare function parseMultipleIsos(value: string | null | undefined): string[];
export declare function serializeMultipleIsos(values: Iterable<string>): string;
export declare function toggleMultipleIso(selected: readonly string[], iso: string): string[];
export declare function isIsoInSpan(iso: string, range: IsoRange): boolean;
export declare function getActiveRangeBounds(committed: IsoRange | null, draft: RangeSelectionDraft): IsoRange | null;
export declare function getDaySelectionAppearance(iso: string, mode: CalendarSelectionMode, options: {
    singleIso?: string;
    multipleIsos?: readonly string[];
    range?: IsoRange | null;
}): DaySelectionAppearance;
/**
 * Advances range selection after a day click.
 *
 * First click sets the anchor; second click commits the range.
 */
export declare function advanceRangeSelection(committed: IsoRange | null, draft: RangeSelectionDraft, iso: string): {
    committed: IsoRange | null;
    draft: RangeSelectionDraft;
};