Clojurians Log v2

I would like to work with a webworker: using Figwheel Main, Leiningen, and Calva. I suppose I need distinct cljs builds for the web page, on one hand, and the webworker, on the other? And distinct src trees, but not distinct target directories if I want Figwheel to be able to serve js from both builds? Some options go in figwheel's X.cljs.edn files where X corresponds to the -b option? And other options go in project.clj? Can figwheel watch both of them at once?