This is dfh@ playing with jj

These are some more descriptions.

flake.lock

@@ -89,7 +89,8 @@
       "inputs": {
         "aux-wiki": "aux-wiki",
         "nixpkgs": "nixpkgs",
-        "snowfall-lib": "snowfall-lib"
+        "snowfall-lib": "snowfall-lib",
+        "treefmt-nix": "treefmt-nix"
       }
     },
     "snowfall-lib": {
@@ -128,6 +129,26 @@
         "repo": "default",
         "type": "github"
       }
+    },
+    "treefmt-nix": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1725271838,
+        "narHash": "sha256-VcqxWT0O/gMaeWTTjf1r4MOyG49NaNxW4GHTO3xuThE=",
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "rev": "9fb342d14b69aefdf46187f6bb80a4a0d97007cd",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "type": "github"
+      }
     }
   },
   "root": "root",

flake.nix

@@ -9,6 +9,11 @@
   inputs.aux-wiki.url = "git+https://git.auxolotl.org/auxolotl/wiki";
   inputs.aux-wiki.flake = false;
 
+  inputs.treefmt-nix = {
+    url = "github:numtide/treefmt-nix";
+    inputs.nixpkgs.follows = "nixpkgs";
+  };
+
   outputs =
     inputs:
     inputs.snowfall-lib.mkFlake {
@@ -22,10 +27,18 @@
         };
       };
 
-      outputs-builder = channels: {
+      outputs-builder =
+        channels:
+        let
+          treefmt = inputs.treefmt-nix.lib.evalModule channels.nixpkgs ./treefmt.nix;
+        in
+        {
           checks."//tmp/this-is-path-traversal" = inputs.self.packages.${channels.nixpkgs.system}.aux-wiki;
           checks."/aux-wiki/path-traversal-2" = inputs.self.packages.${channels.nixpkgs.system}.aux-wiki;
           checks."aux-wiki/all-good" = inputs.self.packages.${channels.nixpkgs.system}.aux-wiki;
+
+          formatter = treefmt.config.build.wrapper;
+          checks.formatting = treefmt.config.build.check inputs.self;
         };
     };
 }

overlays/lix-docs/default.nix

@@ -1,5 +1,5 @@
 { channels, ... }:
-final: prev: {
+_final: _prev: {
   lix-docs = channels.nixpkgs.lix.overrideAttrs {
     pname = "lix-docs";
     postBuild = ''

packages/lix-docs/default.nix

@@ -13,7 +13,7 @@ stdenv.mkDerivation {
   inherit (lix-docs) version;
   pname = "lix-docs-md";
 
-  src = lix-docs.src;
+  inherit (lix-docs) src;
 
   nativeBuildInputs = [
     vim

packages/nixos-options/default.nix

@@ -40,7 +40,7 @@ let
     );
 
   options =
-    (buildFromConfig ({ ... }: { }) (config: config.system.build.manual.optionsJSON)).x86_64-linux;
+    (buildFromConfig (_: { }) (config: config.system.build.manual.optionsJSON)).x86_64-linux;
 
   customPython = pkgs.python312.withPackages (ps: [
     ps.jq

packages/nixpkgs-lib-docs/locations-json.nix

@@ -20,7 +20,7 @@ let
   libset =
     toplib:
     builtins.map (subsetname: {
-      subsetname = subsetname;
+      inherit subsetname;
       functions = libDefPos [ ] toplib.${subsetname};
     }) (builtins.map (x: x.name) lib.amg.libsets);
 
@@ -58,7 +58,7 @@ let
       };
     };
 
-  relativeLocs = (builtins.map fnLocationRelative liblocations);
+  relativeLocs = builtins.map fnLocationRelative liblocations;
   sanitizeId = builtins.replaceStrings [ "'" ] [ "-prime" ];
 
   urlPrefix = "https://github.com/NixOS/nixpkgs/blob/${revision}";

packages/nixpkgs-manual/python-interp-table.nix

@@ -7,7 +7,7 @@
   ),
 }:
 let
-  lib = pkgs.lib;
+  inherit (pkgs) lib;
   inherit (lib.attrsets) attrNames filterAttrs;
   inherit (lib.lists)
     filter

treefmt.nix

@@ -0,0 +1,24 @@
+_: {
+  # Used to find the project root
+  projectRootFile = "flake.nix";
+
+  # Files not to format.
+  settings.global.excludes = [
+    ".editorconfig"
+    ".jj/**"
+    "LICENSE"
+  ];
+
+  # nix
+  programs.nixfmt-rfc-style.enable = true;
+  programs.statix.enable = true;
+  programs.deadnix.enable = true;
+
+  # markdown
+  programs.prettier = {
+    enable = true;
+    settings = {
+      editorconfig = true;
+    };
+  };
+}