Ooh, good point. Thanks Junebuggena.
Hmm, I could enclose all three sides of the triangle, add an attached roof, but leave the bottom open so they can fly up into it.... Maybe add some lower poles so they have a way to hop up.
I have a pretty well built run, completely enclosed with 1/2 hardware cloth on all sides including top and bottom, with panels over part of the top to keep out the rain. While I was away for a week, apparently the roost inside the coop fell, and now no amount of bribery will convince my chickens...