fcitx5 on labwc

modules/applications/labwc/nixos.nix

@@ -1,4 +1,9 @@
-{ inputs, pkgs, ... }:
+{
+  inputs,
+  pkgs,
+  lib,
+  ...
+}:
 let
   unstable = inputs.nixpkgs-unstable.legacyPackages.${pkgs.stdenv.hostPlatform.system};
 in
@@ -7,4 +12,31 @@ in
     enable = true;
     package = unstable.labwc;
   };
+
+  # NixOS decides whether a graphical session manages graphical-session.target
+  # itself by checking XDG_CURRENT_DESKTOP against a hard-coded list. Labwc is
+  # currently absent from that list, so NixOS starts
+  # nixos-fake-graphical-session.target before Labwc is ready.
+  #
+  # This configuration uses Home Manager's Labwc systemd integration, which
+  # imports the Wayland environment and starts labwc-session.target correctly.
+  # Mark the Labwc session as systemd-aware before the display-manager wrapper
+  # performs its hard-coded check. Otherwise services such as Fcitx5 can start
+  # before WAYLAND_DISPLAY is available.
+  #
+  # Despite the services.xserver namespace, this session wrapper is also used
+  # for Wayland sessions by display managers such as Ly.
+  services.xserver.displayManager.sessionCommands = lib.mkAfter ''
+    case ":''${XDG_CURRENT_DESKTOP:-}:" in
+      *:labwc:*)
+        case ":$XDG_CURRENT_DESKTOP:" in
+          *:X-NIXOS-SYSTEMD-AWARE:*)
+            ;;
+          *)
+            export XDG_CURRENT_DESKTOP="$XDG_CURRENT_DESKTOP:X-NIXOS-SYSTEMD-AWARE"
+            ;;
+        esac
+        ;;
+    esac
+  '';
 }