/**
 * Semantic Cache for LLM responses
 *
 * Cache LLM responses with similarity-based retrieval for cost savings.
 * Uses database prefix scanning to store and retrieve cached responses.
 */
import { EmbeddedDatabase } from './embedded';
export interface CacheEntry {
    key: string;
    value: string;
    embedding: number[];
    timestamp: number;
    ttl?: number;
    metadata?: Record<string, any>;
}
export interface CacheHit extends CacheEntry {
    score: number;
}
export interface CacheStats {
    count: number;
    hits: number;
    misses: number;
    hitRate: number;
    memoryUsage: number;
}
/**
 * Semantic Cache with vector similarity matching
 *
 * @example
 * ```typescript
 * const cache = new SemanticCache(db, 'llm_responses');
 *
 * // Store response
 * await cache.put(
 *   'What is Python?',
 *   'Python is a high-level programming language...',
 *   embedding,
 *   3600  // TTL in seconds
 * );
 *
 * // Check cache
 * const hit = await cache.get(queryEmbedding, 0.85);
 * if (hit) {
 *   console.log(`Cache HIT: ${hit.value} (similarity: ${hit.score})`);
 * }
 * ```
 */
export declare class SemanticCache {
    private db;
    private cacheName;
    private prefix;
    private hits;
    private misses;
    constructor(db: EmbeddedDatabase, cacheName: string);
    /**
     * Store a cached response
     */
    put(key: string, value: string, embedding: number[], ttlSeconds?: number, metadata?: Record<string, any>): Promise<void>;
    /**
     * Retrieve cached response by similarity
     *
     * @param queryEmbedding - Query embedding vector
     * @param threshold - Minimum cosine similarity (0-1)
     * @returns Best matching cache entry or null
     */
    get(queryEmbedding: number[], threshold?: number): Promise<CacheHit | null>;
    /**
     * Delete a specific cache entry
     */
    delete(key: string): Promise<void>;
    /**
     * Clear all entries in this cache
     */
    clear(): Promise<number>;
    /**
     * Get cache statistics
     */
    stats(): Promise<CacheStats>;
    /**
     * Purge expired entries
     */
    purgeExpired(): Promise<number>;
}
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