This took me forever to figure out, so I hope I’ll be able to save someone a few hours of annoyance someday.
Serendeputy is always recalculating, and I needed to make sure that the browsers wouldn’t cache the page when someone clicked off and then hit the back button. This is how I was able to do it.
response.headers["Cache-Control"] = "no-cache, no-store, max-age=0, must-revalidate"
response.headers["Pragma"] = "no-cache"
response.headers["Expires"] = "Fri, 01 Jan 1990 00:00:00 GMT"
I just tested this out, and it works on Safari and Firefox on the Mac, and IE7, Firefox and Chrome on the PC.
Hope this helps.