import type { NonceCacheLike } from './types.js';
/**
 * In-memory nonce cache for anti-replay.
 * TTL defines how long a nonce is considered "seen".
 */
export declare class NonceCache implements NonceCacheLike {
    private readonly cache;
    private readonly ttlMs;
    constructor(ttlMs?: number);
    /**
     * Returns true if nonce is valid (not seen within TTL). Records nonce on success.
     */
    isValid(nonce: string, timestamp: number): boolean;
    private cleanup;
    clear(): void;
}
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