I once read a story about a recently graduated co-ed that took up a job House Sitting along the California Coast, Perhaps Big Sur??? It was an uber modern house set part way up a hill near the Pacific Ocean. In one part of the house was an extremely automated gym with all sorts of exercise machines. The rest of the mansion was uber modern and controlled by an AI, I think.

She is a fitness nut and was thrilled to see the machines. There was even a way to set the time and the occupant could not get off of it until the time was up and only if the performance was satisfactory. As time wore on this included penetrative machine sex.

At the end of the story, the co-ed posits that the previous owner might have expired in the home, killed by the AI. I don't remember if she works out a way to escape or not. I do not remember if I read this at BCTS, Literotica, Fictionmania, or some other site?