export type FailoverReason = 'auth' | 'format' | 'rate_limit' | 'billing' | 'timeout' | 'unknown';
export declare function isRateLimitErrorMessage(raw: string): boolean;
export declare function isTimeoutErrorMessage(raw: string): boolean;
export declare function isBillingErrorMessage(raw: string): boolean;
export declare function isAuthErrorMessage(raw: string): boolean;
export declare function isFormatErrorMessage(raw: string): boolean;
export declare function classifyFailoverReason(err: unknown): FailoverReason;