nix.nixPath = [
    "nixpkgs=${sources.nixpkgs}"
    "nixos-config=/home/emily/etc/nixos/${config.networking.hostName}.nix"
    "nixpkgs-overlays=${
      builtins.toFile "overlays.nix" ''
        [
          (_: _: {
            emily.sources = builtins.fromJSON
              (builtins.readFile
                ${builtins.toFile "source-paths.json"
                  (builtins.toJSON
                    (builtins.removeAttrs sources [ "__functor" ]))});
          })
          ${lib.concatMapStringsSep
            "\n  "
            (path: "(import ${path})")
            overlay-paths}
        ]
      ''
    }"
  ];
  nix.useSandbox = true;
  nix.distributedBuilds = true;
  nix.extraOptions = ''
    builders-use-substitutes = true
  '';

  nixpkgs.overlays =
    [ (_: _: { emily.sources = sources; }) ] ++
    map import overlay-paths;