import type { EmailLogger } from '../utils/logger.js';
/**
 * Custom error for IM token fetch failures
 */
export declare class TokenFetchError extends Error {
    readonly attempts: number;
    readonly lastError: unknown;
    readonly retryable: boolean;
    readonly name = "TokenFetchError";
    constructor(message: string, attempts: number, lastError: unknown, retryable?: boolean);
}
/**
 * Check if an error is retryable
 */
export declare function isRetryableError(error: any): boolean;
/**
 * Format error for logging
 */
export declare function formatError(error: unknown): string;
/**
 * Validate parameters for token fetch
 */
export declare function validateParams(apiKey: string, email: string): void;
/**
 * Validate token API response
 */
export declare function validateResponse(response: any): void;
/**
 * Fetch IM token once (single attempt, no retry)
 */
declare function fetchTokenOnce(apiKey: string, email: string, log: EmailLogger): Promise<string>;
export { fetchTokenOnce };
/**
 * Fetch IM token with automatic retry
 *
 * @param apiKey - API key (ck_live_xxx format)
 * @param email - User email address
 * @param log - Logger instance
 * @returns IM access token
 * @throws TokenFetchError if all attempts fail
 */
export declare function fetchIMToken(apiKey: string, email: string, log: EmailLogger): Promise<string>;