import type { Overflow, TimeDurationUnit } from "../../types/index.js";
/**
 * Return a PlainTime ISO string with `units` added to `value`.
 *
 * - Validates `value`, `units`, and `amount` before performing the add.
 * - Returns "" for invalid inputs.
 *
 * `overflow` ("constrain" (default) | "reject") is accepted for API consistency with sibling
 * add functions, but PlainTime arithmetic always wraps around the clock (e.g. 23:00 + 2 hours
 * = 01:00) rather than producing an out-of-range value, so it has no observable effect here.
 *
 * @param value ISO PlainTime string
 * @param units Partial<Record<TimeDurationUnit, number>> object specifying units to add
 * @param options optional: overflow ("constrain" | "reject" — accepted but inert, see above)
 * @returns ISO PlainTime string after addition, or "" on invalid input
 *
 * @example addTime("12:00:00", { hours: 1 }) // "13:00:00"
 * @example addTime("invalid", { hours: 1 }) // ""
 */
export declare function addTime(value: string, units: Partial<Record<TimeDurationUnit, number>>, options?: {
    overflow?: Overflow;
}): string;