export declare const WEEKDAYS: readonly ["MO", "TU", "WE", "TH", "FR", "SA", "SU"];
export type Weekday = (typeof WEEKDAYS)[number];
export declare const WEEKDAY_LABELS: Record<Weekday, string>;
export type Frequency = "DAILY" | "WEEKLY" | "MONTHLY";
export type ParsedRRule = {
    frequency: Frequency;
    interval: number;
    byWeekdays: Weekday[];
    byMonthDays: number[];
};
export type RRuleValidationResult = {
    ok: true;
    parsed: ParsedRRule;
} | {
    ok: false;
    message: string;
};
export declare function validateRRule(rrule: string): RRuleValidationResult;
/**
 * Parse a minimal RRULE string (subset of RFC 5545).
 * Supports FREQ, INTERVAL, BYDAY, BYMONTHDAY.
 */
export declare function parseRRule(rrule: string): ParsedRRule;
/**
 * Build an RRULE string from structured values.
 */
export declare function buildRRule(values: ParsedRRule): string;
/**
 * Human-readable preview: "Every Monday" / "Every 2 weeks on Mon, Wed, Fri"
 */
export declare function describeRRule(rrule: string | ParsedRRule): string;
/**
 * Expand an RRULE into a sorted list of local date strings (YYYY-MM-DD).
 * Operates on UTC-anchored wall-clock dates — timezone conversion is
 * the caller's responsibility.
 */
export declare function expandRRule(rrule: string | ParsedRRule, fromDate: Date, toDate: Date, limit?: number): string[];