export type WithOptionalTail<T> = T extends readonly [...infer Head, infer Last] ? readonly [...Head, Last?] : T;
export interface PageResourceItem {
    id: string;
    object: 'page';
    uri: string;
    referrer?: string;
}
interface PageResourceGlobals {
    location?: {
        href: string;
    };
    document?: {
        referrer?: string;
    };
}
export declare function buildPageResourceItem(globals?: PageResourceGlobals): PageResourceItem | undefined;
export declare function appendPageResourceIfNeeded<TData>(event: string, data: TData, optedIn: ReadonlySet<string>): TData;
export declare function enrichMessageWithPageResource<M extends {
    type: string;
    data?: unknown;
}>(message: M, optedIn: ReadonlySet<string>): M;
export {};