flake-parts: Almost done with yggdrasil

modules/flake-parts/formatter.nix

@@ -0,0 +1,50 @@
+{
+  inputs,
+  lib,
+  ...
+}:
+{
+  imports = [
+    inputs.treefmt-nix.flakeModule
+    inputs.git-hooks.flakeModule
+  ];
+
+  perSystem =
+    { self', ... }:
+    {
+      treefmt = {
+        projectRootFile = "flake.nix";
+        programs = {
+          deadnix.enable = true;
+          jsonfmt.enable = true;
+          nixfmt.enable = true;
+          prettier.enable = true;
+          shfmt.enable = true;
+          statix.enable = true;
+          yamlfmt.enable = true;
+        };
+        settings = {
+          on-unmatched = "fatal";
+          global.excludes = [
+            "*.envrc"
+            ".editorconfig"
+            "*.directory"
+            "*.face"
+            "*.fish"
+            "*.png"
+            "*.toml"
+            "*.svg"
+            "*.xml"
+            "*/.gitignore"
+            "_to_migrate/*"
+            "LICENSE"
+          ];
+        };
+      };
+
+      pre-commit.settings.hooks.nix-fmt = {
+        enable = true;
+        entry = lib.getExe self'.formatter;
+      };
+    };
+}