https://www.mediawiki.org/wiki/Architecture_guidelines
I have worked on improving the architecture guidelines, but I think they
are still a draft, and I'm sorry about that, because I wanted to have that
done by now. Specifically, I think the "YAGNI" and "separation of
concerns"
sections could be clearer, and I'd love more examples of times in the past
we did data-driven change well or badly.
I suggest that we talk onlist, onwiki, and in a future RfC meeting about
those points. I'm this week moving on to working on API documentation
https://www.mediawiki.org/wiki/Data_%26_Developer_Hub but I can participate
in those discussions.
Sumana Harihareswara
Senior Technical Writer
Wikimedia Foundation