fix(hyprland): mark zeus main output for xwayland

configs/nixos/hosts/zeus/default.nix

@@ -1,6 +1,7 @@
 {
   config,
   lib,
+  pkgs,
   ...
 }:
 # zeus — Ryzen desktop with AMD graphics.
@@ -48,20 +49,35 @@
   modules.desktop.apps.steam.enable = true;
   modules.desktop.apps.vencord.enable = true;
 
-  home-manager.users.${config.user.name}.wayland.windowManager.hyprland.settings.monitor = [
-    {
-      output = "HDMI-A-1";
-      mode = "1920x1080@120";
-      position = "0x0";
-      scale = 1;
-      transform = 3;
-    }
-    {
-      output = "DP-3";
-      mode = "2560x1440@239.96";
-      position = "1080x0";
-      scale = 1;
-    }
-  ];
+  home-manager.users.${config.user.name}.wayland.windowManager.hyprland.settings = {
+    monitor = [
+      {
+        output = "HDMI-A-1";
+        mode = "1920x1080@120";
+        position = "0x0";
+        scale = 1;
+        transform = 3;
+      }
+      {
+        output = "DP-3";
+        mode = "2560x1440@239.96";
+        position = "1080x0";
+        scale = 1;
+      }
+    ];
+
+    # Some XWayland games query RandR primary output instead of Hyprland's
+    # layout, so mark the main panel explicitly.
+    on = {
+      _args = [
+        "hyprland.start"
+        (lib.generators.mkLuaInline ''
+          function()
+            hl.exec_cmd("${pkgs.xrandr}/bin/xrandr --output DP-3 --primary")
+          end
+        '')
+      ];
+    };
+  };
 
 }