check out GraphQL when thinking about this

I think it would be favourable to still return the request data but at the base of the response, something like:

{
  article: 'Example',
  access: 'all-access',
  agent: 'user',
  granularity: 'daily',
  project: 'en.wikipedia',
  items: [
    {
      timestamp: "2016090700",
      views: 123
    }, {
      timestamp: "2016090800",
      views: 456
    }
  ]
}

This is useful for applications making multiple asynchronous requests, so that the "promises" callbacks have all the data they need for processing. Depending on the implementation, we'd otherwise have to keep track of the request data outside of the callbacks, which is tricky since each promise may be resolved at a different time, if that makes sense. Also, if no items are returned, we lose the request data entirely. I can provide some pseudocode if that would be helpful.

Yes, we can make the optimization factor out everything that won't vary in the reaponse.