/**
 * useWorkerNotifications – listen to worker messages and maintain running state, counts, history, and derived stats.
 * @module useWorkerNotifications
 */
/** Supported worker event types for tracking. Worker should postMessage with these shapes. */
export type WorkerEventType = "task_start" | "task_end" | "task_fail" | "queue_size";
export interface WorkerNotificationEvent {
    type: WorkerEventType;
    taskId?: string;
    duration?: number;
    error?: string;
    size?: number;
    timestamp: number;
}
export interface UseWorkerNotificationsOptions {
    /** Max events to keep in history. Default 100. */
    maxHistory?: number;
    /** Window in ms for throughput calculation (completed per second). Default 1000. */
    throughputWindowMs?: number;
}
export interface UseWorkerNotificationsReturn {
    /** Task IDs currently running (received task_start, not yet task_end/task_fail). */
    runningTasks: string[];
    /** Total tasks that completed successfully. */
    completedCount: number;
    /** Total tasks that failed. */
    failedCount: number;
    /** Recent events (oldest first), capped at maxHistory. */
    eventHistory: WorkerNotificationEvent[];
    /** Average task duration in ms (from task_end events that include duration). */
    averageDurationMs: number;
    /** Completed tasks per second over the throughput window. */
    throughputPerSecond: number;
    /** Last reported queue size (from queue_size events); 0 if never sent. */
    currentQueueSize: number;
    /** Default view: all active worker data and progress in one object. */
    progress: {
        runningTasks: string[];
        completedCount: number;
        failedCount: number;
        averageDurationMs: number;
        throughputPerSecond: number;
        currentQueueSize: number;
        totalProcessed: number;
        recentEventCount: number;
    };
}
/**
 * Listens to a Worker's messages and maintains state: running tasks, completed/failed counts,
 * event history, execution time per task, average duration, throughput per second, and queue size.
 * Worker should postMessage with: { type: 'task_start'|'task_end'|'task_fail'|'queue_size', taskId?, duration?, error?, size? }.
 *
 * @param worker - The Worker instance to listen to, or null/undefined to listen to nothing.
 * @param options - Optional maxHistory and throughputWindowMs.
 * @returns State and derived stats plus a default progress object.
 */
export declare function useWorkerNotifications(worker: Worker | null | undefined, options?: UseWorkerNotificationsOptions): UseWorkerNotificationsReturn;