/**
 * @license
 * Copyright 2025 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */
export declare function isNodeError(error: unknown): error is NodeJS.ErrnoException;
export declare function getErrorMessage(error: unknown): string;
export declare class FatalError extends Error {
    readonly exitCode: number;
    constructor(message: string, exitCode: number);
}
export declare class FatalAuthenticationError extends FatalError {
    constructor(message: string);
}
export declare class FatalInputError extends FatalError {
    constructor(message: string);
}
export declare class FatalSandboxError extends FatalError {
    constructor(message: string);
}
export declare class FatalConfigError extends FatalError {
    constructor(message: string);
}
export declare class FatalTurnLimitedError extends FatalError {
    constructor(message: string);
}
export declare class FatalToolExecutionError extends FatalError {
    constructor(message: string);
}
export declare class FatalCancellationError extends FatalError {
    constructor(message: string);
}
export declare class ForbiddenError extends Error {
}
export declare class UnauthorizedError extends Error {
}
export declare class BadRequestError extends Error {
}
export declare class NotYetImplemented extends Error {
    constructor(message?: string);
}
export declare function toFriendlyError(error: unknown): unknown;
/**
 * Checks if an error is a 401 authentication error.
 * Uses structured error properties from MCP SDK errors first.
 *
 * @plan PLAN-20250219-GMERGE021.R3.P03
 * @requirement REQ-GMERGE021-R3-002
 */
export declare function isAuthenticationError(error: unknown): boolean;
/**
 * Checks if an error is a 404 Not Found error with proper detection.
 * Uses typed error checking first, falls back to anchored pattern matching.
 * Avoids false positives from strings like "port 40404" or "code 4040".
 *
 * @param error - The error to check
 * @returns True if the error is a 404 error
 */
export declare function is404Error(error: unknown): boolean;