/**
 * Simple in-memory rate limiter with automatic cleanup of expired entries.
 *
 * Tracks request counts per key (typically IP address) within a sliding window.
 * Periodically evicts expired entries to prevent unbounded memory growth.
 */
export declare class RateLimiter {
    private readonly limits;
    private readonly maxPerMinute;
    private readonly windowMs;
    private lastCleanup;
    private static readonly CLEANUP_INTERVAL;
    constructor(maxPerMinute: number, windowMs?: number);
    /** Number of tracked entries (for monitoring/testing). */
    get size(): number;
    /** Check if a request from the given key is allowed. */
    isAllowed(key: string): boolean;
    /** Evict expired entries if enough time has passed since last cleanup. */
    private maybeCleanup;
}