Introduce a home-manager module

home-manager.nix

@@ -0,0 +1,43 @@
+self: {
+  lib,
+  pkgs,
+  config,
+  ...
+}:
+with lib; let
+  cfg = config.programs.git-series-manager;
+
+  tomlFormat = pkgs.formats.toml {};
+in {
+  options.programs.git-series-manager = {
+    enable = mkEnableOption "git-series-manager, a way to manage git patchsets";
+
+    package = mkOption {
+      type = types.package;
+      description = "Package to use by git-series-manager";
+      default = self.defaultPackage."${pkgs.system}";
+    };
+
+    settings = mkOption {
+      inherit (tomlFormat) type;
+      example = lib.literalExpression ''
+        {
+          sendmail_args = ["--sendmail-cmd=customSendmail" "--to=mail@list.com"];
+          repo_url_base = "https://my.git-forge.com/my/project/";
+          ci_url = "https://my.jenkins.instance/''${component}/job/''${branch}/''${ci_job}";
+          editor = "nvim";
+        }
+      '';
+      description = ''
+        git-series-manager global configuration, can also be configured through ''${repo}/.patches/config.toml
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    home.packages = [ cfg.package ];
+
+    xdg.configFile."git-series-manager/config.toml".source = 
+    tomlFormat.generate "config.toml" cfg.settings;
+  };
+}