Why did you specify "during class initialization" only? When I print dir(Foo.Bar) at top-level, there is no __qualname__.

Then, note that '__name__' is not listed either, so it's not about new attributes.

It was chosen that dir(someClass) tries to list the know attributes of instances, not the attributes of the class object itself (__bases__, __mro__, and so on).
See https://docs.python.org/3.4/library/functions.html#dir