/**
 * Registry of known topic -> payload types.
 *
 * Consumers augment this interface via declaration merging so that
 * `pubSub.subscribe` / `pubSub.publish` enforce payload types per topic:
 *
 * ```ts
 * declare module '@changke/staticnext-lib' {
 *   interface PubSubTopics {
 *     'user:login': {userId: string};
 *   }
 * }
 * ```
 *
 * Topics not declared here fall back to `unknown`, preserving the legacy
 * untyped behavior.
 */
export interface PubSubTopics {
    [topic: string]: unknown;
}
type ListenerFn<T = unknown> = (data: T) => void;
interface Subscribed {
    remove: () => void;
}
/**
 * Simple event hub
 */
declare class PubSub {
    topics_: Map<string, ListenerFn<unknown>[]>;
    constructor();
    subscribe<K extends string>(topic: K, listener: ListenerFn<PubSubTopics[K]>): Subscribed;
    publish<K extends string>(topic: K, data?: PubSubTopics[K]): void;
    subscribeOnce<K extends string>(topic: K, listener: ListenerFn<PubSubTopics[K]>): Subscribed;
}
declare const pubSub: PubSub;
export default pubSub;
export type { ListenerFn, Subscribed };