export declare const SIGNAL_EXIT_CODES: {
    readonly SIGHUP: 129;
    readonly SIGINT: 130;
    readonly SIGTERM: 143;
};
export type TerminalSignal = keyof typeof SIGNAL_EXIT_CODES;
/**
 * Without a parent handler, terminal Ctrl+C kills this process inside spawn.sync before the
 * child result exists — no event, no flush. `onSignal` runs at most once; a second signal
 * exits rather than waiting on it.
 */
export declare function installSignalGuard(onSignal: (signal: TerminalSignal) => Promise<void> | void): () => void;