import ' rollup-plugin-inject-process-env';
/**
 * How long a conversation must sit idle, on top of the calendar day changing, before it
 * expires when the widget config does not say.
 */
export declare const DEFAULT_SESSION_EXPIRATION = "4h";
/**
 * A conversation expires only when BOTH the visitor's local calendar day has changed since
 * the last message AND at least `duration` has passed. So a visitor who browses the site
 * over an afternoon keeps one conversation, and one chatting at 11pm is not greeted afresh
 * at 1am - but tomorrow's visit starts clean.
 */
export declare function checkSessionExpiration(duration: string | undefined, lastMessageTimestamp: number | undefined, _lastTimestamp: number, now?: number): boolean;