/**
 * @omnifolio/rate-governor — IP Extraction Helpers
 *
 * Extract the real client IP from common proxy / CDN headers.
 * Works behind Cloudflare, AWS ALB, GCP Cloud Run, nginx, etc.
 *
 * Built by OmniFolio — https://omnifolio.app
 */
/**
 * Extract the client IP from a standard `Headers` object.
 *
 * Checks (in order): `cf-connecting-ip`, `x-forwarded-for`, `x-real-ip`.
 * Returns `'unknown'` if no IP can be determined.
 *
 * ```ts
 * const ip = getClientIP(request.headers);
 * const result = checkRateLimit(`ip:${ip}`, Presets.STANDARD);
 * ```
 */
export declare function getClientIP(headers: {
    get(name: string): string | null;
}): string;
/**
 * Build a rate-limit identifier from a request.
 *
 * If a `userId` is provided, uses `user:{userId}`.
 * Otherwise falls back to `ip:{clientIP}`.
 */
export declare function buildIdentifier(headers: {
    get(name: string): string | null;
}, userId?: string): string;
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