/**
 * Cross-package classification for errors that describe an expected outcome
 * rather than an unexpected failure.
 *
 * The symbol is registered globally so the marker survives package duplication
 * and worker/VM boundaries without relying on a particular Error constructor.
 */
export declare const DESIGNED_ERROR: unique symbol;
/** Mark an Error as a designed outcome before it crosses package boundaries. */
export declare function markDesignedError<T extends Error>(error: T): T;
/** Return true when a throwable carries the trusted designed-outcome marker. */
export declare function isDesignedError(error: unknown): boolean;