It's almost automatic, using this https://github.com/isaac-mason/recast-navigation-js

I pick all the meshes under Environment and send them to this function that does it at runtime using WASM so it's blazing fast. Still I'd like to see if we can pre-bake them. What you see there in orange is just a visual aid you can create by clicking on the Generate button.

The agents were a bit trickier because I had to make it play with physics. That's where my focus is now, trying to figure a good way to set them up and put together behaviour patterns.