Here is a big fight I am going to have to make with myself ahead. And actually, I can use community input.
The current plan for Spritely has been for me to use the tools I am writing in Racket. I've been very happy hacking in Racket personally and the tooling is coming along.
However, I am duplicating work that the Agoric folks are doing in making an ocap secure substrate rich enough to do this stuff: https://agoric.com/
Except... their stuff is in Javascript. (cotd ...)