In 2013, WMF was still holding it's traditional All-Hands meetings in September (rather than January). Just prior to the All-Hands, we had "Tech Days", which was a two day invite-only event.
ArchCom was new back then. That was where we were starting to plan the first Architecture Summit in January 2014.
This 2013 email (from me) about the event was only published publicly (by me) in early 2016:
We're just about at the same point (chronologically) in the planning process for WikiDev17 as we were in planning for Architecture Summit 2014. I believe I'm going to find myself repeating many of the things I said back then.