export declare class RelayPrefixPool {
    private readonly pools;
    private readonly indices;
    private readonly poolSize;
    constructor(poolSize?: number);
    /**
     * Get the next prefix for a relay host via round-robin.
     * Lazily initializes the pool (and triggers DNS warmup) on first access.
     */
    getPrefix(relayHost: string): string;
    /**
     * Generate a pool of random prefixes and kick off DNS warmup.
     */
    private initPool;
    /**
     * Send lightweight pings to each prefixed hostname to prime the browser's
     * DNS cache and TLS session cache. Failures are silently ignored —
     * this is best-effort optimization.
     */
    private warmup;
    /** Generate a random 8-char alphanumeric prefix. */
    private static randomPrefix;
}
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