import type { LlmGenerationEvent, LlmToolSpan, LlmToolSpanContext, LlmTraceSink } from '@cat-factory/kernel';
/** Minimal structured logger (pino-compatible); optional. */
export interface LangfuseLogger {
    warn(obj: Record<string, unknown>, msg?: string): void;
}
export interface LangfuseSinkConfig {
    /** Langfuse public key (`pk-lf-…`). */
    publicKey: string;
    /** Langfuse secret key (`sk-lf-…`). */
    secretKey: string;
    /** Host of the Langfuse instance. Default: Langfuse Cloud (`https://cloud.langfuse.com`). */
    baseUrl?: string;
    /** Optional logger for swallowed errors. */
    logger?: LangfuseLogger;
    /** Injectable fetch (tests); defaults to the global `fetch`. */
    fetchImpl?: typeof fetch;
}
export declare class LangfuseTraceSink implements LlmTraceSink {
    private readonly endpoint;
    private readonly authorization;
    private readonly logger?;
    private readonly fetchImpl;
    constructor(config: LangfuseSinkConfig);
    recordGeneration(event: LlmGenerationEvent): Promise<void>;
    recordToolSpans(context: LlmToolSpanContext, spans: LlmToolSpan[]): Promise<void>;
    private send;
}
/** Build a {@link LangfuseTraceSink}. Returns the opt-in sink wired into a facade. */
export declare function createLangfuseSink(config: LangfuseSinkConfig): LangfuseTraceSink;
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