import type { NonceCacheLike } from './types.js';
/**
 * Persistent nonce cache using IndexedDB (browser) and localStorage.
 * 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.
     * Uses localStorage for synchronous access (required by NonceCacheLike interface).
     * Also persists to IndexedDB in background if available.
     */
    isValid(nonce: string, timestamp: number): boolean;
    /**
     * Synchronous validation using localStorage (primary storage).
     */
    private isValidSync;
    /**
     * Persist nonce to IndexedDB in background (async, non-blocking).
     */
    private persistToIndexedDB;
    /**
     * Cleanup expired entries (localStorage and IndexedDB).
     */
    private cleanupSync;
    /**
     * Cleanup expired entries from IndexedDB (async, non-blocking).
     */
    private cleanupIndexedDB;
    /**
     * Clear all entries.
     */
    clear(): void;
}
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