{
  description = "Python development env with venv + Jupyter";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs = { self, nixpkgs, flake-utils }:
    flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = import nixpkgs { inherit system; };
      in
      {
        devShells.default = pkgs.mkShell {
          packages = with pkgs; [
            python312
            python312Packages.virtualenv
            python312Packages.pip

            python312Packages.jupyterlab
            python312Packages.ipykernel
          ];

          shellHook = ''
            echo "🐍 Python: $(python3 --version)"

            if [ ! -d .venv ]; then
              python3 -m venv .venv
              . .venv/bin/activate
              pip install --upgrade pip wheel
            else
              . .venv/bin/activate
            fi

            python -m ipykernel install --user --name "nix-env" --display-name "Python (nix)"
          '';
        };
      });
}