hm test

flake.nix

@@ -22,7 +22,7 @@
       flake-utils,
       ...
     }@inputs:
-    flake-utils.lib.eachDefaultSystem (
+    (flake-utils.lib.eachDefaultSystem (
       system:
       let
         pkgs = import inputs.nixpkgs {
@@ -105,16 +105,31 @@
             # MY_CUSTOM_VAR = "some value";
           }
         );
+
+        # winit dlopens libwayland and wgpu the vulkan loader at runtime, which
+        # rpath alone does not cover; wrap the binary with LD_LIBRARY_PATH so
+        # the package also runs outside the devShell (e.g. from systemd).
+        barbar = pkgs.symlinkJoin {
+          name = "barbar-${my-crate.version}";
+          paths = [ my-crate ];
+          nativeBuildInputs = [ pkgs.makeWrapper ];
+          postBuild = ''
+            wrapProgram $out/bin/core \
+              --prefix LD_LIBRARY_PATH : ${pkgs.lib.makeLibraryPath guiLibs}
+          '';
+          meta.mainProgram = "core";
+        };
       in
       {
         checks = {
           inherit my-crate;
         };
 
-        packages.default = my-crate;
+        packages.default = barbar;
 
         apps.default = flake-utils.lib.mkApp {
-          drv = my-crate;
+          drv = barbar;
+          exePath = "/bin/core";
         };
 
         devShells.default = craneLib.devShell {
@@ -135,5 +150,9 @@
           packages = guiLibs ++ pkgs.lib.optionals pkgs.stdenv.hostPlatform.isLinux [ pkgs.mold ];
         };
       }
-    );
+    ))
+    // {
+      # System-independent, so it lives outside eachDefaultSystem.
+      homeManagerModules.default = import ./nix/home-manager.nix self;
+    };
 }

nix/home-manager.nix

@@ -0,0 +1,86 @@
+# Home Manager module for barbar.
+#
+#   imports = [ inputs.barbar.homeManagerModules.default ];
+#
+# Generates barbar.toml from `programs.barbar.settings` and runs the bar as a
+# systemd user service bound to the graphical session.
+self:
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+let
+  cfg = config.programs.barbar;
+  toml = pkgs.formats.toml { };
+  configFile = toml.generate "barbar.toml" cfg.settings;
+in
+{
+  options.programs.barbar = {
+    enable = lib.mkEnableOption "barbar, a Wayland layer-shell status bar";
+
+    package = lib.mkOption {
+      type = lib.types.package;
+      default = self.packages.${pkgs.stdenv.hostPlatform.system}.default;
+      defaultText = lib.literalExpression "barbar.packages.\${system}.default";
+      description = "The barbar package to run.";
+    };
+
+    settings = lib.mkOption {
+      type = toml.type;
+      default.order = {
+        left = [ ];
+        middle = [ ];
+        right = [ ];
+      };
+      defaultText = lib.literalExpression ''{ order = { left = [ ]; middle = [ ]; right = [ ]; }; }'';
+      description = ''
+        Contents of barbar.toml, written verbatim. Only `order` is required by
+        barbar; `[display]`, `[modules.*]` and `[services.*]` are optional.
+        See test.toml in the barbar repo for the full schema.
+      '';
+      example = lib.literalExpression ''
+        {
+          display = {
+            monitor = "DP-2";
+            height = 24;
+          };
+          order = {
+            left = [ "workspaces" "weather" ];
+            middle = [ ];
+            right = [ "clock" ];
+          };
+          modules.clock.show_seconds = false;
+        }
+      '';
+    };
+
+    systemd.enable = lib.mkOption {
+      type = lib.types.bool;
+      default = true;
+      description = "Run barbar as a systemd user service.";
+    };
+
+    systemd.target = lib.mkOption {
+      type = lib.types.str;
+      default = "graphical-session.target";
+      description = "Systemd target the bar is bound to.";
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    systemd.user.services.barbar = lib.mkIf cfg.systemd.enable {
+      Unit = {
+        Description = "barbar status bar";
+        After = [ cfg.systemd.target ];
+        PartOf = [ cfg.systemd.target ];
+      };
+      Service = {
+        ExecStart = "${lib.getExe' cfg.package "core"} --config ${configFile}";
+        Restart = "on-failure";
+      };
+      Install.WantedBy = [ cfg.systemd.target ];
+    };
+  };
+}