Is a missing __init__.pyi in a bundled stub cause a false positive in Pylance?

[hunterhogan]

Is it possible that because sympy-stubs does not have 'combinatorics/init.pyi', Pylance could not find the logical path sympy.combinatorics.Permutation?

In VSCode-insiders, Pylance was reporting Permutation and PermutationGroup could not be found with this statement:

from sympy.combinatorics import Permutation, PermutationGroup

I was three-times confused because 1) the SymPy documentation uses that logical path, 2) the installed package seemed to be re-exporting from that logical path (see __init__.py), and 3) my personally generated stubs for SymPy re-export on that path (see here; I didn't find sympy-stubs in this repo until today). So I used the following statements, which worked fine.

from sympy.combinatorics.perm_groups import PermutationGroup
from sympy.combinatorics.permutations import Permutation

But I was still confused, so I started poking around the stub files and the installed package files--while using VSCode to navigate and open the files. It seems that I somehow caused Pylance to stop using "%USERPROFILE%.vscode-insiders\extensions\ms-python.vscode-pylance-2025.8.100\dist\bundled\stubs\sympy-stubs\combinatorics..." and start using my stubs. Now, from sympy.combinatorics import Permutation works as expected.

I think that adds up to Pylance reporting it couldn't find from sympy.combinatorics import Permutation because the bundled stubs don't have __init__.pyi to re-export those symbols.

BUT, I could be completely wrong. There are a lot of moving parts in this system, and my knowledge is minuscule.

I know y'all aren't Pylance, but there is a non-zero chance this log could be useful to you.

Python Language Server.log