import type { CompletionRequest } from '../types/messages.js';
import type { NexusResponse } from '../types/response.js';
import { type EmbeddingProvider } from '../hallucination/retrieval.js';
/** Options for the semantic response cache. */
export interface SemanticCacheOptions {
    /** Turns it on. Off by default, and then every lookup misses. */
    enabled?: boolean;
    /** Cosine similarity at which a cached answer is reused, from 0 to 1. Defaults to 0.88. */
    similarityThreshold?: number;
    /** Entries kept before the oldest is dropped. Defaults to 500. */
    maxEntries?: number;
    /** Lifetime of an entry, in seconds. Defaults to 5 minutes. */
    ttlSeconds?: number;
    /** Embeds requests. Defaults to hashed term vectors, which need no provider. */
    embed?: EmbeddingProvider;
}
/**
 * Reuses a cached response for a request that means nearly the same as an earlier one, not only one
 * that is identical.
 */
export declare class SemanticCache {
    private options;
    private entries;
    private embed;
    constructor(options?: SemanticCacheOptions);
    /**
     * The cached response for the most similar earlier request above the threshold, or `undefined`.
     */
    get(request: CompletionRequest): Promise<NexusResponse | undefined>;
    /** Caches a response under its request's embedding. */
    set(key: string, request: CompletionRequest, response: NexusResponse): Promise<void>;
    /** Removes every entry. */
    clear(): void;
}