/**
 * Compares two dot-separated numeric version strings.
 *
 * Each segment is parsed as an integer with missing or invalid segments treated as `0`.
 * The comparison iterates over the length of `a`, which matches the current upgrader usage
 * where the left-hand side is the reference version shape.
 *
 * @param a Reference version string.
 * @param b Version string to compare against.
 * @returns `-1` when `a < b`, `1` when `a > b`, otherwise `0`.
 */
export declare function compareVersions(a: string, b: string): number;