const internalSync: SyncConfig<TItem>['sync'] = (params) => {
  // Creates observer when collection starts sync
  const localObserver = new QueryObserver(queryClient, observerOptions)
  
  // Subscribes immediately and stays subscribed
  const actualUnsubscribeFn = localObserver.subscribe((result) => {
    // ... sync logic
  })
  
  // Only unsubscribes when collection is cleaned up
  return async () => {
    actualUnsubscribeFn()
    // ...
  }
}

const internalSync: SyncConfig<TItem>['sync'] = (params) => {
  const { collection } = params
  let localObserver: QueryObserver | null = null
  let queryUnsubscribe: (() => void) | null = null

  // Track when collection gains/loses subscribers
  const originalAddSubscriber = collection.addSubscriber
  const originalRemoveSubscriber = collection.removeSubscriber

  // Override to manage QueryObserver lifecycle
  collection.addSubscriber = function() {
    const wasInactive = this.activeSubscribersCount === 0
    originalAddSubscriber.call(this)
    
    // Create QueryObserver when first subscriber added
    if (wasInactive && \!localObserver) {
      localObserver = new QueryObserver(queryClient, observerOptions)
      queryUnsubscribe = localObserver.subscribe((result) => {
        // ... existing sync logic
      })
    }
  }

  collection.removeSubscriber = function() {
    originalRemoveSubscriber.call(this)
    
    // Cleanup QueryObserver when last subscriber removed
    if (this.activeSubscribersCount === 0 && localObserver) {
      queryUnsubscribe?.()
      localObserver = null
      queryUnsubscribe = null
      // Now TanStack Query's staleTime timer can start
    }
  }

  return async () => {
    // Restore original methods
    collection.addSubscriber = originalAddSubscriber
    collection.removeSubscriber = originalRemoveSubscriber
    
    // Final cleanup
    queryUnsubscribe?.()
    await queryClient.cancelQueries({ queryKey })
    queryClient.removeQueries({ queryKey })
  }
}

// In collection.ts
private notifySubscriberCountChange(count: number) {
  this.emit('subscriberCountChanged', count)
}

// In query-db-collection
collection.on('subscriberCountChanged', (count) => {
  if (count === 0 && localObserver) {
    // Unsubscribe QueryObserver
  } else if (count === 1 && \!localObserver) {
    // Subscribe QueryObserver  
  }
})