{
  system ? builtins.currentSystem,
  sources ? import ../npins,
  pkgs ? import sources.nixpkgs { inherit system; },
}:
{
  # shell for testing TF directly
  shell = pkgs.mkShellNoCC {
    packages = [
      pkgs.openssh
      pkgs.httpie
      pkgs.jq
    ];
  };

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