refactor(waybar): register custom modules

configs/nixos/modules/desktop/session/hyprland/hyprlock.nix

@@ -37,6 +37,14 @@ let
       ${lib.getExe' pkgs.swayosd "swayosd-client"} --custom-message "${sleepOffIcon}"
     fi
   '';
+
+  idleLockStatus = pkgs.writeShellScript "waybar-idle-lock-status" ''
+    if ${lib.getExe' pkgs.systemd "systemctl"} --user is-active --quiet lockscreen-idle-inhibit.service; then
+      printf '{"text":"${sleepOffIcon}","tooltip":"Idle locking inhibited","class":"inhibited"}\n'
+    else
+      printf '{"text":"","class":"idle"}\n'
+    fi
+  '';
 in
 {
   options.modules.desktop.session.hyprland.hyprlock.enable =
@@ -97,5 +105,15 @@ in
         };
       };
     };
+
+    registry.waybar-module.${config.networking.hostName}."custom/idle-lock" = {
+      order = 20;
+      settings = {
+        return-type = "json";
+        exec = "${idleLockStatus}";
+        interval = "once";
+        signal = 9;
+      };
+    };
   };
 }

configs/nixos/modules/desktop/session/mako.nix

@@ -5,6 +5,25 @@
   ...
 }:
 # mako as the notification daemon: toasts, a do-not-disturb mode, and history recall.
+let
+  glyph = code: builtins.fromJSON ''"\u${code}"'';
+
+  # Renders and toggles mako's do-not-disturb mode.
+  # With no mako daemon answering, the status reads "notifications on", keeping
+  # the widget inert rather than broken.
+  dndStatus = pkgs.writeShellScript "waybar-dnd-status" ''
+    if ${lib.getExe' pkgs.mako "makoctl"} mode 2>/dev/null | ${lib.getExe pkgs.gnugrep} -qx dnd; then
+      printf '{"text":"${glyph "f1f6"}","tooltip":"Do not disturb: on","class":"dnd"}\n'
+    else
+      printf '{"text":"${glyph "f0f3"}","tooltip":"Notifications on","class":"active"}\n'
+    fi
+  '';
+
+  dndToggle = pkgs.writeShellScript "waybar-dnd-toggle" ''
+    ${lib.getExe' pkgs.mako "makoctl"} mode -t dnd >/dev/null 2>&1
+    ${lib.getExe' pkgs.procps "pkill"} -RTMIN+8 waybar
+  '';
+in
 {
   options.modules.desktop.session.mako.enable = lib.mkEnableOption "the mako notification daemon";
 
@@ -35,5 +54,16 @@
         command = "${lib.getExe' pkgs.mako "makoctl"} restore";
       };
     };
+
+    registry.waybar-module.${config.networking.hostName}."custom/dnd" = {
+      order = 80;
+      settings = {
+        return-type = "json";
+        exec = "${dndStatus}";
+        on-click = "${dndToggle}";
+        interval = "once";
+        signal = 8;
+      };
+    };
   };
 }

configs/nixos/modules/desktop/session/waybar.nix

@@ -6,64 +6,62 @@
 }:
 # Waybar: a top status bar reading system state at a glance.
 let
-  vpnClient = config.modules.network.vpn-client;
+  waybarModulesFor =
+    position:
+    map (module: module.name) (
+      lib.sort (a: b: a.order < b.order) (
+        lib.filter (module: module.position == position) (staticWaybarModules ++ registeredWaybarModules)
+      )
+    );
+
+  staticWaybarModules = [
+    {
+      name = "hyprland/workspaces";
+      position = "left";
+      order = 10;
+    }
+    {
+      name = "clock";
+      position = "center";
+      order = 10;
+    }
+    {
+      name = "mpris";
+      position = "right";
+      order = 30;
+    }
+    {
+      name = "wireplumber";
+      position = "right";
+      order = 40;
+    }
+    {
+      name = "custom/network";
+      position = "right";
+      order = 60;
+    }
+    {
+      name = "battery";
+      position = "right";
+      order = 70;
+    }
+  ];
+
+  registeredWaybarModules = lib.mapAttrsToList (
+    name: module:
+    module
+    // {
+      inherit name;
+    }
+  ) hostWaybarModules;
+
+  hostWaybarModules = lib.attrByPath [ config.networking.hostName ] { } config.registry.waybar-module;
 
   # A Nerd Font Private-Use-Area codepoint as a literal character, decoded
   # through JSON so the glyph survives as bytes rather than an editor paste.
   g = code: builtins.fromJSON ''"\u${code}"'';
 
-  sleepOffIcon = builtins.fromJSON ''"\udb81\udcb3"'';
-
-  # Renders and toggles mako's do-not-disturb mode.
-  # With no mako daemon answering, the status reads "notifications on", keeping
-  # the widget inert rather than broken.
-  dndStatus = pkgs.writeShellScript "waybar-dnd-status" ''
-    if ${lib.getExe' pkgs.mako "makoctl"} mode 2>/dev/null | ${lib.getExe pkgs.gnugrep} -qx dnd; then
-      printf '{"text":"${g "f1f6"}","tooltip":"Do not disturb: on","class":"dnd"}\n'
-    else
-      printf '{"text":"${g "f0f3"}","tooltip":"Notifications on","class":"active"}\n'
-    fi
-  '';
-
-  dndToggle = pkgs.writeShellScript "waybar-dnd-toggle" ''
-    ${lib.getExe' pkgs.mako "makoctl"} mode -t dnd >/dev/null 2>&1
-    ${lib.getExe' pkgs.procps "pkill"} -RTMIN+8 waybar
-  '';
-
-  # Lit while a wf-recorder capture is running.
-  # Empty text collapses the widget when idle, so it shows nothing until then.
-  recStatus = pkgs.writeShellScript "waybar-recording-status" ''
-    if ${lib.getExe' pkgs.procps "pgrep"} -x wf-recorder >/dev/null; then
-      printf '{"text":"${g "f03d"}","tooltip":"Recording","class":"recording"}\n'
-    else
-      printf '{"text":"","class":"idle"}\n'
-    fi
-  '';
-
-  idleLockStatus = pkgs.writeShellScript "waybar-idle-lock-status" ''
-    if ${lib.getExe' pkgs.systemd "systemctl"} --user is-active --quiet lockscreen-idle-inhibit.service; then
-      printf '{"text":"${sleepOffIcon}","tooltip":"Idle locking inhibited","class":"inhibited"}\n'
-    else
-      printf '{"text":"","class":"idle"}\n'
-    fi
-  '';
-
-  vpnStatus = pkgs.writeShellScript "waybar-vpn-status" ''
-    interface=${lib.escapeShellArg vpnClient.interface}
-
-    if ! ${lib.getExe' pkgs.iproute2 "ip"} link show dev "$interface" >/dev/null 2>&1; then
-      printf '{"text":"","class":"idle"}\n'
-      exit 0
-    fi
-
-    ipaddr=$(${lib.getExe' pkgs.iproute2 "ip"} -4 -o addr show dev "$interface" | ${lib.getExe' pkgs.gawk "awk"} '{ print $4; exit }')
-
-    ${lib.getExe pkgs.jq} -cn \
-      --arg text "󰲝" \
-      --arg tooltip "VPN $interface: ''${ipaddr:-no IPv4}" \
-      --arg class "active" \
-      '{ text: $text, tooltip: $tooltip, class: $class }'
-  '';
+  registeredWaybarModuleSettings = lib.mapAttrs (_name: module: module.settings) hostWaybarModules;
 
   networkStatus = pkgs.writeShellScript "waybar-network-status" ''
     active=$(
@@ -122,26 +120,16 @@ in
         }
       '';
 
-      settings.mainBar = {
+      settings.mainBar = lib.mkMerge [
+        {
           layer = "top";
           position = "top";
           height = 30;
           spacing = 8;
 
-        modules-left = [ "hyprland/workspaces" ];
-        modules-center = [ "clock" ];
-        modules-right = [
-          "custom/recording"
-          "custom/idle-lock"
-          "mpris"
-          "wireplumber"
-        ]
-        ++ lib.optional vpnClient.enable "custom/vpn"
-        ++ [
-          "custom/network"
-          "battery"
-          "custom/dnd"
-        ];
+          modules-left = waybarModulesFor "left";
+          modules-center = waybarModulesFor "center";
+          modules-right = waybarModulesFor "right";
 
           # Per-application icons for the windows on each workspace, mapped from
           # window class with a neutral glyph for anything unlisted.
@@ -185,12 +173,6 @@ in
             on-click = "${lib.getExe' pkgs.wireplumber "wpctl"} set-mute @DEFAULT_AUDIO_SINK@ toggle";
           };
 
-        "custom/vpn" = {
-          return-type = "json";
-          exec = "${vpnStatus}";
-          interval = 5;
-        };
-
           "custom/network" = {
             return-type = "json";
             exec = "${networkStatus}";
@@ -212,30 +194,9 @@ in
               critical = 10;
             };
           };
-
-        "custom/dnd" = {
-          return-type = "json";
-          exec = "${dndStatus}";
-          on-click = "${dndToggle}";
-          interval = "once";
-          signal = 8;
-        };
-
-        # Recording state has no event to hook, so the widget samples the
-        # wf-recorder process once a second.
-        "custom/recording" = {
-          return-type = "json";
-          exec = "${recStatus}";
-          interval = 1;
-        };
-
-        "custom/idle-lock" = {
-          return-type = "json";
-          exec = "${idleLockStatus}";
-          interval = "once";
-          signal = 9;
-        };
-      };
+        }
+        registeredWaybarModuleSettings
+      ];
     };
   };
 }

configs/nixos/modules/desktop/utilities/recording.nix

@@ -6,14 +6,16 @@
 }:
 # Keybound screen recording: pick a region, then toggle a video-only capture.
 let
-  slurp = "${pkgs.slurp}/bin/slurp";
-  wf-recorder = "${pkgs.wf-recorder}/bin/wf-recorder";
-  notify-send = "${pkgs.libnotify}/bin/notify-send";
-  pgrep = "${pkgs.procps}/bin/pgrep";
-  pkill = "${pkgs.procps}/bin/pkill";
-  date = "${pkgs.coreutils}/bin/date";
-  mkdir = "${pkgs.coreutils}/bin/mkdir";
-  xdgUserDir = "${pkgs.xdg-user-dirs}/bin/xdg-user-dir";
+  slurp = lib.getExe pkgs.slurp;
+  wf-recorder = lib.getExe pkgs.wf-recorder;
+  notify-send = lib.getExe' pkgs.libnotify "notify-send";
+  pgrep = lib.getExe' pkgs.procps "pgrep";
+  pkill = lib.getExe' pkgs.procps "pkill";
+  date = lib.getExe' pkgs.coreutils "date";
+  mkdir = lib.getExe' pkgs.coreutils "mkdir";
+  xdgUserDir = lib.getExe' pkgs.xdg-user-dirs "xdg-user-dir";
+
+  glyph = code: builtins.fromJSON ''"\u${code}"'';
 
   # A single key both starts and stops.
   # A running wf-recorder is stopped with SIGINT so it finalises the file.
@@ -36,6 +38,16 @@ let
     ${wf-recorder} -g "$region" -f "$file"
     ${notify-send} -a "Screen recording" "Recording saved" "$file"
   '';
+
+  # Lit while a wf-recorder capture is running.
+  # Empty text collapses the widget when idle, so it shows nothing until then.
+  recordingStatus = pkgs.writeShellScript "waybar-recording-status" ''
+    if ${pgrep} -x wf-recorder >/dev/null; then
+      printf '{"text":"${glyph "f03d"}","tooltip":"Recording","class":"recording"}\n'
+    else
+      printf '{"text":"","class":"idle"}\n'
+    fi
+  '';
 in
 {
   options.modules.desktop.utilities.recording.enable =
@@ -50,5 +62,13 @@ in
       };
     };
 
+    registry.waybar-module.${config.networking.hostName}."custom/recording" = {
+      order = 10;
+      settings = {
+        return-type = "json";
+        exec = "${recordingStatus}";
+        interval = 1;
+      };
+    };
   };
 }

configs/nixos/modules/network/vpn-client.nix

@@ -1,10 +1,30 @@
 {
   config,
   lib,
+  pkgs,
   ...
 }:
 let
   cfg = config.modules.network.vpn-client; # NOLINT(let_order)
+
+  vpnIcon = builtins.fromJSON ''"\udb83\udc9d"'';
+
+  vpnStatus = pkgs.writeShellScript "waybar-vpn-status" ''
+    interface=${lib.escapeShellArg cfg.interface}
+
+    if ! ${lib.getExe' pkgs.iproute2 "ip"} link show dev "$interface" >/dev/null 2>&1; then
+      printf '{"text":"","class":"idle"}\n'
+      exit 0
+    fi
+
+    ipaddr=$(${lib.getExe' pkgs.iproute2 "ip"} -4 -o addr show dev "$interface" | ${lib.getExe' pkgs.gawk "awk"} '{ print $4; exit }')
+
+    ${lib.getExe pkgs.jq} -cn \
+      --arg text "${vpnIcon}" \
+      --arg tooltip "VPN $interface: ''${ipaddr:-no IPv4}" \
+      --arg class "active" \
+      '{ text: $text, tooltip: $tooltip, class: $class }'
+  '';
 in
 {
   options.modules.network.vpn-client = {
@@ -57,6 +77,15 @@ in
       vpn-off = "sudo systemctl stop 'wireguard-${cfg.interface}*.service' wireguard-${cfg.interface}.target";
     };
 
+    registry.waybar-module.${config.networking.hostName}."custom/vpn" = {
+      order = 50;
+      settings = {
+        return-type = "json";
+        exec = "${vpnStatus}";
+        interval = 5;
+      };
+    };
+
     systemd.targets."wireguard-${cfg.interface}".wantedBy = lib.mkForce [ ];
 
     networking.wireguard.interfaces.${cfg.interface} = {

configs/nixos/registry/waybar-module.nix

@@ -0,0 +1,29 @@
+{ lib, ... }:
+{
+  type = lib.types.submodule {
+    options = {
+      position = lib.mkOption {
+        type = lib.types.enum [
+          "left"
+          "center"
+          "right"
+        ];
+        default = "right";
+        description = "Selects the Waybar section that shows the module.";
+      };
+
+      order = lib.mkOption {
+        type = lib.types.int;
+        default = 100;
+        example = 50;
+        description = "Sorts the module within its Waybar section.";
+      };
+
+      settings = lib.mkOption {
+        type = lib.types.attrsOf lib.types.anything;
+        default = { };
+        description = "Sets the Waybar module configuration.";
+      };
+    };
+  };
+}