{
  perSystem = {lib, ...}: {
    treefmt.programs = {
      alejandra = {
        enable = true;
        excludes = ["_sources/*.nix"];
      };
      oxfmt = let
        oxfmtConfig = with lib;
          pipe ./.oxfmtrc.json [builtins.readFile builtins.fromJSON];
      in {
        enable = true;
        includes = ["*.json" "*.md" "*.toml" "*.yaml"];
        excludes = oxfmtConfig.ignorePatterns;
      };
      just = {
        enable = true;
        includes = [".justfile"];
      };
      typos = let
        config = with lib;
          pipe ./.typos.toml [builtins.readFile fromTOML];
      in {
        enable = true;
        includes = ["*"];
        excludes = ["assets/*"] ++ config.files.extend-exclude;
        configFile = toString ./.typos.toml;
        # Disable all extra option in treefmt module.
        # Use config file.
        sort = false;
        isolated = false;
        hidden = false;
        noIgnore = false;
        noIgnoreDot = false;
        noIgnoreGlobal = false;
        noIgnoreParent = false;
        noIgnoreVCS = false;
        binary = false;
        noCheckFilenames = false;
        noCheckFiles = false;
        noUnicode = false;
      };
    };
  };
}