Right now, our module discovery doesn't support namespace packages -- or rather, it requires that projects specify namespace packages explicitly via the namespace-packages setting.

I'd like to remove this setting, and ensure that namespace packages "just work".

One option is to take inspiration from Mypy, where they effectively mark a directory without a __init__.py[i] file as a namespace package if it's within a directory that contains an __init__.py[i] file, and provide escape hatches for explicitly specifying package bases.

Another option is to take inspiration Pyright, where AFAICT they allow you to specify multiple roots which are effectively your package bases.