refactor: statix, deadnix, alejandra

system/home.nix

@@ -0,0 +1,29 @@
+{
+  config,
+  tree,
+  machine,
+  systemType,
+  lib,
+  ...
+}: let
+  inherit (lib.lists) optional;
+in {
+  home-manager = {
+    useGlobalPkgs = true;
+    useUserPackages = true;
+    sharedModules = with tree;
+      [
+        home.modules
+        home.state
+      ]
+      ++ optional (tree.${systemType} ? home) tree.${systemType}.home;
+
+    users.kat.imports = with tree; [
+      home.base
+    ];
+    extraSpecialArgs = {
+      inherit tree machine;
+      parent = config;
+    };
+  };
+}

system/nix.nix

@@ -0,0 +1,23 @@
+{
+  config,
+  lib,
+  inputs,
+  ...
+}: let
+  inherit (lib.attrsets) mapAttrs mapAttrsToList;
+  inherit (lib.lists) optional;
+  inherit (lib.strings) versionAtLeast;
+in {
+  nix = {
+    nixPath = mapAttrsToList (name: flake: "${name}=${flake}") inputs;
+    registry = mapAttrs (_: flake: {inherit flake;}) inputs;
+
+    settings = {
+      experimental-features = optional (versionAtLeast config.nix.package.version "2.4") "nix-command flakes";
+      substituters = ["https://arc.cachix.org" "https://kittywitch.cachix.org" "https://nix-community.cachix.org"];
+      trusted-public-keys = ["arc.cachix.org-1:DZmhclLkB6UO0rc0rBzNpwFbbaeLfyn+fYccuAy7YVY=" "kittywitch.cachix.org-1:KIzX/G5cuPw5WgrXad6UnrRZ8UDr7jhXzRTK/lmqyK0=" "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="];
+      auto-optimise-store = true;
+      trusted-users = ["root" "@wheel"];
+    };
+  };
+}

system/overlay.nix

@@ -0,0 +1,7 @@
+{inputs, ...}: {
+  nixpkgs = {
+    overlays = map (path: import "${path}/overlay.nix") [
+      inputs.arcexprs
+    ];
+  };
+}