import type { NonceCacheLike } from './types.js';
/**
 * Persistent nonce cache using IndexedDB (browser) or localStorage (fallback).
 * Implements NonceCacheLike interface for use with verifyLoginProof.
 */
export declare class PersistentNonceCache implements NonceCacheLike {
    private readonly ttlMs;
    private readonly storageKey;
    private readonly useIndexedDB;
    private db;
    constructor(ttlMs?: number, storageKey?: string);
    /**
     * Initialize IndexedDB if available.
     */
    init(): Promise<void>;
    /**
     * Check if nonce is valid (not seen within TTL). Records nonce on success.
     * Note: IndexedDB operations are async, but NonceCacheLike interface requires sync.
     * This implementation uses localStorage for synchronous access.
     * For true IndexedDB persistence, consider making the interface async.
     */
    isValid(nonce: string, timestamp: number): boolean;
    /**
     * Synchronous validation using localStorage (fallback).
     */
    private isValidSync;
    /**
     * Cleanup expired entries (localStorage).
     */
    private cleanupSync;
    /**
     * Clear all entries.
     */
    clear(): void;
}
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