I am seeing this same issue on an old M1 MacBook Pro with Apple Intelligence enabled.

I have a M4 Mac running macOS26 beta 3 and Xcode 26. I can see the FoundationsModel run in the #Preview {} but when I try to run my code in the iPhoneSimulator, I get a state of: "On-device model isn'r ready yet". I take this to mean that (1) I have the macOS AI enabled, and #Preview is fine, but the iPhone simulator has AI turned on but is not quite ready. I left it overnight, and it is still in this state. Is there anything I can do to get the Simulator working?

I have found a new issue in the iOS 26 public beta (23A5336a) that seemed to block invite acceptance on the iOS26 device (but do work in reverse). I have posted separately on that item. I hope you can help with that issue as well!

This helps explain what I was seeing. The message was not deterministic. That helps. I would still prefer an API that allows developers to ask the session how many tokens they have processed.