{
  system ? builtins.currentSystem,
  sources ? import ../npins,
  pkgs ? import sources.nixpkgs { inherit system; },
}:
let
  inherit (pkgs) lib;
  setup = import ./setup.nix { inherit lib pkgs sources; };
in
{
  # shell for testing TF directly
  shell = pkgs.mkShellNoCC {
    packages = [
      (import ./tf.nix { inherit lib pkgs; })
      pkgs.direnv
      pkgs.jaq
      pkgs.nixos-generators
      setup
    ];
  };

  tests = pkgs.callPackage ./tests.nix { };

  # re-export inputs so they can be overridden granularly
  # (they can't be accessed from the outside any other way)
  inherit
    sources
    system
    pkgs
    ;
}