/**
 * Free proxy auto-selection for bot-protection bypass.
 *
 * Source: proxifly/free-proxy-list (MIT) via jsDelivr CDN.
 * These are datacenter proxies — they bypass simple IP blocks but NOT
 * full Cloudflare Bot Manager / Akamai. For Cloudflare-protected sites,
 * users need a residential proxy (Bright Data, Oxylabs, etc.).
 */
/**
 * Pick a working free proxy. Tests in parallel batches of 10 with a 4s timeout.
 * Returns null if no working proxy found (not an error — crawl can proceed without proxy).
 */
export declare function pickFreeProxy(): Promise<string | null>;
export type ProxyTier = 'free' | 'datacenter' | 'residential' | 'premium';
export interface ProxyTierConfig {
    /** List of proxy URLs for this tier. E.g. ['http://user:pass@dc1.proxy:8080'] */
    urls: string[];
    tier: ProxyTier;
}
/**
 * Tiered proxy manager with per-domain error histograms.
 *
 * Tracks success/failure per domain and automatically escalates to higher proxy tiers
 * on consecutive failures. Applies time-decay to probe returning to lower tiers.
 *
 * Usage:
 *   const mgr = new TieredProxyManager([{ tier: 'datacenter', urls: [...] }]);
 *   const proxy = await mgr.selectProxy('api.salesforce.com');
 *   // ... make request ...
 *   mgr.recordResult('api.salesforce.com', success);
 */
export declare class TieredProxyManager {
    private tiers;
    private domainHistory;
    private readonly ESCALATE_AFTER;
    private readonly DECAY_AFTER_MS;
    constructor(configs: ProxyTierConfig[]);
    private getHistory;
    private lowestAvailableTier;
    /** Pick a proxy URL for this domain, based on its tier history. */
    selectProxy(domain: string): string | null;
    /** Record a request result for a domain. Triggers tier escalation on repeated failures. */
    recordResult(domain: string, success: boolean): void;
    stats(): Array<{
        domain: string;
        tier: ProxyTier;
        successRate: number;
        totalRequests: number;
    }>;
}