import { type AttributionTouch } from "./attribution-source.js";
/**
 * The durable copy of first touch. Our server sets it, because Safari caps
 * cookies written by page JavaScript at seven days; the browser's own `an_ft`
 * cookie and localStorage copy stay the immediate, 30-day copies. Signup and
 * the browser both pick between the copies with `preferFirstTouch`, so they
 * agree on which visit is first touch.
 */
export declare const FIRST_TOUCH_SERVER_COOKIE_NAME = "an_fts";
export declare const FIRST_TOUCH_SERVER_COOKIE_VERSION = "1";
export declare const FIRST_TOUCH_SERVER_PATH = "/_agent-native/auth/attribution";
/** Counted from the first visit, never extended by later ones. */
export declare const FIRST_TOUCH_SERVER_LIFETIME_SECONDS: number;
/** `name=value` budget, so this and the browser's cookies fit one header. */
export declare const FIRST_TOUCH_SERVER_COOKIE_MAX_BYTES = 1500;
export interface TimedFirstTouch extends AttributionTouch {
    landed_at?: string;
}
/**
 * Which of two records is first touch: the first visit that had a source,
 * else the first visit. `incumbent` wins a tie, so a copy never displaces the
 * value it came from.
 */
export declare function preferFirstTouch<T extends TimedFirstTouch>(incumbent: T | null | undefined, challenger: T | null | undefined): T | null;
/** Whether two records are the same visit, however each copy was trimmed. */
export declare function isSameFirstTouch(a: TimedFirstTouch | null | undefined, b: TimedFirstTouch | null | undefined): boolean;
/**
 * When the durable copy expires: a year after the visit, or `null` once that
 * year is over. A missing or future visit time counts from now.
 */
export declare function firstTouchServerExpiry(touch: TimedFirstTouch, now?: number): Date | null;