AMR does include a comprehensive wiki to provide the data for simulations (which you can find when clicking on “Simulator” in the top menu bar and then opening the menu to the left) and to have a relatively simple way for everybody to get more specific info.
You can, for example, find the complete rotation data there and take a closer look (i.e. https://www.askmrrobot.com/wow/theory/rotation/amrmagearcanemain?spec=MageArcane&version=live for arcane mages) and looking for the relevant comments you can pinpoint the exact action pretty easily.
For that situation the action is coded like that:
which means your second variant should be the correct one.