import type { ChatConfig, Attachment } from '../types/index.ts';
export declare class N8nApiError extends Error {
    readonly status?: number;
    /**
     * True when the underlying transport or status code indicates the request can be safely
     * retried (network failure, 408, 429, 502/503/504). 4xx responses (other than 408/429) and
     * any error that occurred after streaming chunks have been written are non-retryable.
     */
    readonly retryable: boolean;
    constructor(message: string, status?: number, retryable?: boolean);
}
/**
 * Send a message to the n8n webhook.
 *
 * Non-streaming: expects { output: string } response.
 * Streaming: SSE; each event contains data: { text: "chunk" } or data: { output: "full" }.
 *
 * Automatically retries transient transport failures (network errors, 408, 429, 502/503/504)
 * with short backoff. Other 4xx and any error that occurs *after* streaming has begun are
 * surfaced immediately — duplicating partially-delivered content would be worse than failing.
 *
 * @param config   Chat configuration
 * @param sessionId  Current session ID (maps to chatSessionKey)
 * @param text     User message text
 * @param language Optional ISO 639-1 code forwarded to n8n
 * @param onChunk  Called with each streaming chunk (enables streaming mode)
 * @returns Full bot response text
 */
export declare function sendMessage(config: ChatConfig, sessionId: string, text: string, language?: string, attachments?: Attachment[], onChunk?: (chunk: string) => void): Promise<string>;