Love your set up! Nicely done!
My run is partitioned into pens that I can close off at will. This past year, I brooded two batches of baby chicks right outdoors in my covered run, using the heating pad system. That's what that blue "box" is. It supports the heating pad.
The chicks grew up in full view of the flock who accepted the chicks as members of the flock, making it a breeze to integrate them.
At age three weeks, I opened the 5 x 7 inch portals so the chicks could access the entire run at that point, but still retaining their safe pen to scoot back into when the going got too rough. But there was surprisingly little attempt at bullying by the older members of the flock. They were all moved into the coop and roosting with the adults at age five weeks.
The first batch of chicks arrived on May 13. The second batch arrived in July. While the second batch enjoyed summer temps, the first batch had to cope with 30 degree nights and 40 degree days. They all did splendidly. I will never brood indoors again.