import type { Temporal } from "@js-temporal/polyfill";
/**
 * Return the start of the specified date `unit` for a `Temporal.PlainDate`.
 *
 * - Always uses Monday as the week start (consistent with roundDate semantics).
 * - Does NOT validate the unit — caller ensures it is a DateUnit.
 *
 * @param source Temporal.PlainDate to round
 * @param unit DateUnit to specify the unit for the start
 * @returns Temporal.PlainDate at the start of the specified unit
 */
export declare function getStartOfDateUnit(source: Temporal.PlainDate, unit: string): Temporal.PlainDate;
/**
 * Add `amount` units of the specified date `unit` to a `Temporal.PlainDate`.
 *
 * - Does NOT validate the unit — caller ensures it is a DateUnit.
 *
 * @param date Temporal.PlainDate to advance
 * @param unit DateUnit to add
 * @param amount number of units to add
 * @returns new Temporal.PlainDate advanced by the specified amount
 */
export declare function addDateUnit(date: Temporal.PlainDate, unit: string, amount: number): Temporal.PlainDate;