uv2nix and pkgs.python3.withPackages?

[tmplt]

Hi, I expose a Python library via

packages = {
    python = pythonSets.mylib;
    python-env = pythonSets.mkVirtualEnv "mylib-env" workspace.deps.default;
};

I'd like to use this downstream in another devShell via some (using flake-parts here for brevity):

devShells = {
    test = pkgs.mkShell {
        packages = [ (pkgs.python3.withPackages (ps: [ config.packages.python ps.numpy ]) ];
    };
    test2 = pkgs.mkShell { packages = [ config.packages.python-env ]; };
};

The library cannot be imported in a nix develop .#test, but it can in a nix develop .#test2.

I'm not very familiar with how Python juggles libraries; what am I missing here? Or is there another mechanism I should use? Thanks!

The purpose is to add more libraries in the downstream shell: numpy, matplotlib, etc.

[adisbladis]

uv2nix isn't using the nixpkgs Python packaging infrastructure, and it's output is not compatible with nixpkgs Python packaging functions.
There is an interoperability function to convert packages into a compatible format: https://pyproject-nix.github.io/pyproject.nix/builders/hacks.html#using-generated-packages-with-nixpkgs.