sway: signal on launch to systemd that the graphical-session.target is ready

this allows auto-launching of other services which require a compositor (i.e. messaging apps)

hosts/modules/gui/sway/default.nix

@@ -340,6 +340,20 @@ in
         })
       ];
 
+      sane.user.services.sway-session = {
+        description = "no-op unit to signal that sway is operational";
+        documentation = [
+          "https://github.com/swaywm/sway/issues/7862"
+          "https://github.com/alebastr/sway-systemd"
+        ];
+        bindsTo = [ "graphical-session.target" ];
+        serviceConfig = {
+          ExecStart = "${pkgs.coreutils}/bin/true";
+          Type = "oneshot";
+          RemainAfterExit = true;
+        };
+      };
+
       sane.user.fs = {
         ".config/waybar/config".symlink.target =
           (pkgs.formats.json {}).generate "waybar-config.json" [

hosts/modules/gui/sway/sway-config

@@ -199,4 +199,9 @@ output "Unknown 0x0637 0x00000000" {
 # for more, see: <repo:nixos/nixpkgs:nixos/modules/programs/wayland/sway.nix>
 include /etc/sway/config.d/*
 
+# signal to systemd that sway is active,
+# and therefore let it start the graphical-session target
+# see `systemctl --user cat sway-session` for links to docs
+exec --no-startup-id systemctl start --user sway-session.service
+
 @extra_lines@