import type { UnixUnit } from "../validate/isValidUnixUnit.js";
/**
 * Return whether `value1` represents an instant strictly before `value2`.
 *
 * - Uses Temporal.Instant.compare to check ordering.
 * - Returns false if either input is invalid.
 *
 * @param value1 first unix epoch value
 * @param value2 second unix epoch value
 * @param options optional: epochUnit ("seconds" | "milliseconds")
 * @returns `true` if `value1` is before `value2`, otherwise `false`
 *
 * @example isBeforeUnix(1704067200, 1706659200) // true
 * @example isBeforeUnix(1706659200, 1706659200) // false
 * @example isBeforeUnix(-1, 0) // true (1969-12-31T23:59:59.999Z is before 1970-01-01T00:00:00Z)
 * @example isBeforeUnix('invalid', 1704067200000) // false
 * @example isBeforeUnix(1704067200000, 'invalid') // false
 */
export declare function isBeforeUnix(value1: number, value2: number, options?: {
    epochUnit?: UnixUnit;
}): boolean;