Thank you for explaining about using leaves! I was just getting ready to post the same thing. And yes, they will need feed. Maybe the wife would be happy if she could find a local feed mill where all of the ingredients were locally sourced? I use my local mill and really have great results for my flock.That sized run will become dirt soon enough. Chickens scratch and will kill the plants in enclosed runs of any reasonable size. Generally, pastured chickens supplement their feed with plants/bugs/etc. It definitely does help the quality of the eggs.
The feed is a good base as it is generally good about providing balanced nutrition to make up for any imbalances in the pasture food. Also, I can tell you from personal experience that you are in a location where the feed will be 90% of their food in the winter.
FYI- Consider using dead leaves instead of wood mulch. Just collect them in the fall and store in bags. They are much easier on chicken feet and they love digging around in it and it gets broken down (along with chicken poo) into an excellent compost you can use in the spring.