BTW

I'm asked to report how mobile performance compares to desktop

that is just wrong way of thinking :(

I should clarify that as my choice of words were not great. During the work on lazy loading images it was important to compare desktop with mobile to show the amount of bytes we saved by looking at reduction in image bytes.

Changes on the desktop site are unfortunately much harder but by comparing the experiences we can use data to make that case more strongly.

Two separate issues:

1. Discovery path from Grafana dashboard to WebPageTest url

2. Discovery path from two WebPageTest urls to the built-in WebPageTest comparison tool. (Yes, it has one)

This task is about both of these.

The separate idea of being able to compare in-depth two arbitrary WebPageTest runs and/or two timeline profiles and find regressions automatically (e.g. two locally generates ones, or two profiles downloaded from a WPT run). Primarily for the purpose of finding regressions between Jenkins runs on each commit, or when working locally and find a way to automatically fail the build or identify potential regressions. That is tracked as T153069.

I think we should do this differently: On alerts we should pre-populate a link with runs before/after a alert, so you as a user just have a link to click on that automatically fills in the right values into the compare page.