/**
 * Custom error types for captcha-canvas to provide actionable and typed error reporting.
 */
export type ErrorCode = 'VALIDATION_ERROR' | 'GENERATION_ERROR' | 'SECURITY_ERROR';
export interface ErrorDetails {
    param?: string;
    expected?: string;
    actual?: unknown;
    suggestion?: string;
    context?: Record<string, unknown>;
}
export declare class CaptchaBaseError extends Error {
    readonly code: ErrorCode;
    readonly details?: ErrorDetails;
    constructor(message: string, code: ErrorCode, details?: ErrorDetails);
}
/**
 * Thrown when configuration/parameter validation fails.
 */
export declare class CaptchaValidationError extends CaptchaBaseError {
    constructor(message: string, details?: ErrorDetails);
}
/**
 * Thrown when rendering/generation fails (e.g., canvas/image errors).
 */
export declare class CaptchaGenerationError extends CaptchaBaseError {
    constructor(message: string, details?: ErrorDetails);
}
/**
 * Thrown when security-related constraints are violated.
 */
export declare class CaptchaSecurityError extends CaptchaBaseError {
    constructor(message: string, details?: ErrorDetails);
}