Site A can't see the cached resources of site B, because it would show that the user has visited site B if the resource is provided too fast. However, if the re

Site A can't see the cached resources of site B, because it would show that the user has visited site B if the resource is provided too fast. However, if the resource is provided with some delay, then site A assumes that site B hasn't been visited. The current solution is to download the same thing twice. It is wasteful and I offer downloading it only once, but if site A asks for a resource for site B, the resource should not be returned immediately, but after a few ms so that site A gets the wrong conclusion. It should work if site A can observe only the result of the request but can't check if a request happened or not.