Web experience needs the equivalent of Screen's workspace persistence

My web experience needs the equivalent of workspace persistence found in Screen. I am too often working with old web applications that process data as you wait. You submit the form and the application responds with "Please wait." And I do. And, when there is a lot of data to process, the wait can be for hours. During this wait nothing untoward can happen to the network connection or the browser. If something untoward does happen then the processing has to begin all over again.

What the Screen web equivalent would allow me to do is to browse the web as I normally would. When I detach from the internet, the pages I have displayed or the ones that are in the process of displaying would be available again when I re-attach to the internet. It is important to remember that these pages are the pages retrieved when I was previously attached to the internet. They are not pages obtained by re-requesting them. Doing so would only begin all over again the long data processing.

With workspace persistence, I could start the data processing using the old web application and not have the worry about a network hiccup or browser crash losing my work.

A road to solving this problem would be an augmented proxy server.