I've answered a few of my own questions by digging through Nimble. * Listing files in your nimble config doesn't use the os module, it uses the functions from the [nimscript module directly](https://nim-lang.org/0.17.0/nimscript.html#listFiles,string) * Overriding the nimble build exit code [isn't possible currently](https://github.com/nim-lang/nimble/blob/10a38a3c90e96bd128dce0538906944a14bf8828/src/nimble.nim#L290-L293)
Things I can't do: * It doesn't look like a build tool dependency is possible. The build script needs to be executed so that the dependency list can be generated. Which is a chicken/egg problem. * It doesn't look like I can read a file from nimscript? Is that correct? * Modelling dependencies doesn't work. I can live without this.
