After weeks of iteration, rebuilding, and redesigning, I finally got the confirmation meow from Aslan. It was like a nod and a different type of Meooow! - it was like he was saying, "You done it dude, great job." I mean, I consulted him on every comfort mode / feature - The 4 modes consist of cuddle, sleep, miss you, and calm. Each one induced a different feeling and reaction. Cuddle was kind of up-tempo and didn't really affect his sleep much; it just kept him engaged and showed that I tried to appreciate him. The "miss you" sound is designed for when I'm on holiday and he's staying at my parents' house or with friends, and then I'll play that through speakers or when I'm back, sleep mode was inspired by the playlists within 5-10 minutes if he is feeling very calm, slow, and usually sleeps. The calming up play is when we are going to back from the vet or on long travels and flights, and that one has slower haptic feedback so vibrations. I just leave that in his comfort basket, and it works.