refactor(nix): split formatter and app outputs

flake.nix

@@ -76,8 +76,11 @@
 
   outputs =
     { self, nixpkgs, ... }@inputs:
+    let
+      system = "x86_64-linux";
+    in
     import ./src/dotfiles {
-      inherit inputs self;
+      inherit inputs self system;
       lib = nixpkgs.lib;
       root = ./configs/nixos;
     };

src/dotfiles/apps.nix

@@ -1,25 +1,16 @@
 {
   inputs,
   lib,
+  formatter,
+  system,
 }:
 let
-  system = "x86_64-linux";
   pkgs = inputs.nixpkgs.legacyPackages.${system};
 
-  treefmtEval = inputs.treefmt-nix.lib.evalModule pkgs {
-    projectRootFile = "flake.nix";
-
-    programs.nixfmt.enable = true;
-
-    settings.formatter.nixfmt.excludes = [
-      "configs/nixos/hosts/*/hardware-configuration.nix"
-    ];
-  };
-
   styleCheck = pkgs.writeShellApplication {
     name = "style-check";
     runtimeInputs = [
-      treefmtEval.config.build.wrapper
+      formatter
       pkgs.statix
       pkgs.deadnix
     ];
@@ -31,9 +22,7 @@ let
   };
 in
 {
-  formatter.${system} = treefmtEval.config.build.wrapper;
-
-  apps.${system}.style-check = {
+  style-check = {
     type = "app";
     program = lib.getExe styleCheck;
   };

src/dotfiles/default.nix

@@ -3,6 +3,7 @@
   inputs,
   self,
   root,
+  system,
 }:
 let
   util = import ./util.nix { inherit lib; };
@@ -38,18 +39,22 @@ let
       ;
     registry = registry.collected;
   };
+
+  formatter = import ./formatter.nix {
+    inherit inputs system;
+  };
 in
 {
-  inherit
-    (import ./apps.nix {
-      inherit
-        inputs
-        lib
-        ;
-    })
-    apps
-    formatter
-    ;
+  formatter.${system} = formatter;
+
+  apps.${system} = import ./apps.nix {
+    inherit
+      inputs
+      lib
+      formatter
+      system
+      ;
+  };
 
   nixosConfigurations = import ./hosts.nix {
     inherit

src/dotfiles/formatter.nix

@@ -0,0 +1,14 @@
+{ inputs, system }:
+let
+  pkgs = inputs.nixpkgs.legacyPackages.${system};
+  treefmtEval = inputs.treefmt-nix.lib.evalModule pkgs {
+    projectRootFile = "flake.nix";
+
+    programs.nixfmt.enable = true;
+
+    settings.formatter.nixfmt.excludes = [
+      "configs/nixos/hosts/*/hardware-configuration.nix"
+    ];
+  };
+in
+treefmtEval.config.build.wrapper