refactor(flake): split root output wiring

flake.nix

@@ -76,10 +76,10 @@
 
   outputs =
     { self, nixpkgs, ... }@inputs:
-    import ./src/dotfiles {
+    import ./src/flake {
       inherit inputs self;
       inherit (nixpkgs) lib;
-      root = ./configs/nixos;
+      root = ./.;
       system = "x86_64-linux";
     };
 }

src/dotfiles/apps.nix

@@ -1,30 +0,0 @@
-{
-  inputs,
-  lib,
-  formatter,
-  system,
-}:
-let
-  pkgs = inputs.nixpkgs.legacyPackages.${system};
-in
-{
-  fix = {
-    type = "app";
-    program = lib.getExe (
-      pkgs.writeShellApplication {
-        name = "fix";
-        runtimeInputs = [
-          formatter
-          pkgs.statix
-          pkgs.deadnix
-        ];
-        text = ''
-          treefmt
-          statix fix .
-          deadnix --edit --exclude configs/nixos/hosts/*/hardware-configuration.nix -- .
-          treefmt
-        '';
-      }
-    );
-  };
-}

src/dotfiles/default.nix

@@ -3,7 +3,6 @@
   inputs,
   self,
   root,
-  system,
 }:
 let
   util = import ./util.nix { inherit lib; };
@@ -41,20 +40,6 @@ let
   };
 in
 {
-  formatter.${system} =
-    (import ./formatter.nix {
-      inherit inputs system;
-    }).config.build.wrapper;
-
-  apps.${system} = import ./apps.nix {
-    inherit
-      inputs
-      lib
-      system
-      ;
-    formatter = self.formatter.${system};
-  };
-
   nixosConfigurations = import ./hosts.nix {
     inherit
       inputs

src/flake/apps.nix

@@ -0,0 +1,41 @@
+{
+  inputs,
+  lib,
+  formatter,
+  system,
+}:
+let
+  pkgs = inputs.nixpkgs.legacyPackages.${system};
+in
+{
+  fix = {
+    type = "app";
+    program = lib.getExe (
+      pkgs.writeShellApplication {
+        name = "fix";
+        runtimeInputs = [
+          formatter
+          pkgs.statix
+          pkgs.deadnix
+        ];
+        text = ''
+          treefmt
+          statix fix \
+            --ignore 'configs/nixos/hosts/*/hardware-configuration.nix' \
+            --ignore 'src/xatu/testdata/**' \
+            --ignore third_party \
+            .
+          deadnix --edit \
+            --exclude \
+              configs/nixos/hosts/neogaia/hardware-configuration.nix \
+              configs/nixos/hosts/pikachu/hardware-configuration.nix \
+              configs/nixos/hosts/zeus/hardware-configuration.nix \
+              src/xatu/testdata \
+              third_party \
+            -- .
+          treefmt
+        '';
+      }
+    );
+  };
+}

src/flake/default.nix

@@ -0,0 +1,33 @@
+{
+  lib,
+  inputs,
+  self,
+  root,
+  system,
+}:
+let
+  dotfiles = import ../dotfiles {
+    inherit
+      inputs
+      lib
+      self
+      ;
+    root = root + "/configs/nixos";
+  };
+in
+{
+  formatter.${system} =
+    (import ./formatter.nix {
+      inherit inputs system;
+    }).config.build.wrapper;
+
+  apps.${system} = import ./apps.nix {
+    inherit
+      inputs
+      lib
+      system
+      ;
+    formatter = self.formatter.${system};
+  };
+}
+// dotfiles

src/flake/formatter.nix

@@ -6,5 +6,7 @@ inputs.treefmt-nix.lib.evalModule inputs.nixpkgs.legacyPackages.${system} {
 
   settings.formatter.nixfmt.excludes = [
     "configs/nixos/hosts/*/hardware-configuration.nix"
+    "src/xatu/testdata/*.nix"
+    "third_party/**"
   ];
 }

src/skills/style/nix/rules/flake.md

@@ -5,8 +5,9 @@
 ### Rule
 
 Add flake inputs in `flake.nix`.
-Put new flake output implementation in `src/dotfiles/default.nix`.
-Use `flake.nix` to pass inputs into that implementation.
+Put root flake output implementation in `src/flake/default.nix`.
+Put domain-specific output implementation near the domain it configures.
+Use `flake.nix` to pass inputs into the root flake implementation.
 
 ### Rationale