This morning she was alert and burbling. I locked the french window open, then lifter Tilda out of her pen and put her on the mat by the open door. She burbled, but no garden chickens came. She turned around and waddled into the main area of the kitchen, watching me as I unloaded the dishwasher.
I went back to her temporary pen and opened the side door. I then tempted her back over there with some corn, and she went in the door to her pen and ate the corn. I then called the garden chickens, picked up Tilda and put her back by the back door.
She burbled at Roobarb, who burbled back. Then Tilda turned around and waddled off.
She's now back in her temporary pen (her choice). The french windows are shut. She watched me while I bustled about.
Clearly she can't stay as a house chicken indefinitely, but she can stay for a day or two while we see how she goes.