/** A cached value and when it expires. */
export interface CacheEntry<T> {
    /** The value. */
    value: T;
    /** Epoch milliseconds when it expires. */
    expiresAt: number;
}
/**
 * A bounded in-memory cache with per-entry expiry, evicting the least recently used entry when
 * full. Holds 500 entries by default.
 */
export declare class MemoryCache<T> {
    private maxEntries;
    private entries;
    constructor(maxEntries?: number);
    /** Returns a value, or `undefined` for a miss or an expired entry. A hit counts as recent use. */
    get(key: string): T | undefined;
    /**
     * Like `get()`, also saying whether an entry was there but had expired, which a caller can report
     * as stale rather than missing. The expired entry is removed either way.
     */
    lookup(key: string): {
        value?: T;
        stale: boolean;
    };
    /** Stores a value. Defaults to 5 minutes. */
    set(key: string, value: T, ttlSeconds?: number): void;
    /** Removes every entry. */
    clear(): void;
    /** Removes an entry. Returns true when one was removed. */
    delete(key: string): boolean;
    /** Removes expired entries, returning how many went. */
    clearExpired(): number;
    /** Size, capacity, and expired entries not yet removed. */
    stats(): {
        size: number;
        maxEntries: number;
        expiredEntries: number;
    };
}
/** A cache key for any value, with object keys sorted so equal values give equal keys. */
export declare function createCacheKey(value: unknown): string;