{ self, ... }:
{
  perSystem =
    {
      pkgs,
      self',
      lib,
      config,
      tera,
      mkCi,
      system,
      ...
    }:
    let
      treefmt = config.treefmt.build.wrapper;
      teraBin = "${tera}/bin/tera";
      rootFile = "flake.nix";
      doc_comment = "<!-- GENERATED: DO NOT EDIT -->";
    in
    {
      packages = {
        docgen = mkCi false (
          pkgs.writeShellApplication {
            name = "docgen";
            runtimeInputs = [
              teraBin
              treefmt
            ];
            text = ''
              if ! test -f "${rootFile}"; then
                  echo "Error: please run docgen from the root of the repository"
                  exit 1
              fi

              echo '{"doc_comment": "${doc_comment}"}' | ${teraBin} --template unionvisor/docs/README.md --include-path unionvisor -s -o unionvisor/README.md > /dev/null 2>&1
              treefmt > /dev/null 2>&1
            '';
          }
        );
      };

      checks = {
        docgen-updated = mkCi (system == "x86_64-linux") (
          pkgs.stdenv.mkDerivation {
            name = "docgen-check";
            src = ../../.;
            buildInputs = [
              pkgs.git
              self'.packages.docgen
            ];
            doCheck = true;
            checkPhase = ''
              set -e
              PRJ=$TMP/project
              cp -r ${self} $PRJ
              chmod -R a+w $PRJ
              cd $PRJ
              export HOME=$TMPDIR
              cat > $HOME/.gitconfig <<EOF
              [user]
              name = Nix
              email = nix@localhost
              [init]
              defaultBranch = main
              EOF
              git init
              git add .
              git commit -m init --quiet
              export LANG=C.UTF-8
              export LC_ALL=C.UTF-8
              ${self'.packages.docgen}/bin/docgen
              git status
              git --no-pager diff --exit-code
              touch $out
            '';
          }
        );
      };
    };
}