An example is worth a thousand words so I put together a reproduction:
https://codesandbox.io/s/microstates-jgdhu
I sum up the issue in the comments there but basically calling a custom transition on a microstate is causing an infinite recursion error. I think because the action in question is still pointing to a previous revision of the microstate. But I'm not sure how to avoid this happening or if Glimmer should have known to re-compute the action when the state was updated?