On Mon, Feb 4, 2013 at 4:59 PM, Arthur Richards arichards@wikimedia.orgwrote:
In the case of the cookie, the header would actually get set by the backend response (from Apache) and I believe Dave cooked up or was planning on cooking some magic to somehow make that information discernable when results are cached.
Opting into the mobile beta as it is currently implemented bypasses varnish caching for all future mobile pageviews for the life of the cookie. So this probably isn't quite right (at least the "when results are cached" part.)