desktop: start bar+wallpaper via systemd; fortune greeter

Move the niri bar (yambar on enzo, waybar on kusanagi) and swaybg wallpaper out
of the shared stowed niri config and into per-machine systemd user services
bound to graphical-session.target, mirroring the existing xdg-user-dirs-update
unit. This makes the bar host-correct (kusanagi previously spawned yambar, which
isn't installed there) and keeps host-specific paths out of the shared config.

Also switch the greetd session to a small wrapper script that shows a fortune
greeting in tuigreet.

Assisted-by: Claude:claude-opus-4-8

1 files changed, 67 insertions, 3 deletions

diff --git a/machines/enzo/desktop.nix b/machines/enzo/desktop.nix
index 8375e13..294fe41 100644
--- a/machines/enzo/desktop.nix
+++ b/machines/enzo/desktop.nix
@@ -11,15 +11,79 @@
   environment.sessionVariables = {
     XCURSOR_THEME = "Adwaita";
     XCURSOR_SIZE = "24";
+
+    # TODO: move to dotfiles
+    LESSHISTFILE = "$HOME/.local/state/lesshst";
+    HISTFILE = "$HOME/.local/state/bash_history";
   };
-  # Cursor theme referenced by XCURSOR_THEME / niri's xcursor-theme. Without this
-  # package the Adwaita cursor files aren't on disk, so named shapes (e.g. the
-  # link "pointer"/hand) fail to load and the cursor never changes on hover.
+
+  nix.settings.use-xdg-base-directories = true;
+
   environment.systemPackages = with pkgs; [
     adwaita-icon-theme
     yambar # text status bar
+    xdg-user-dirs
   ];
 
+  # --- XDG user directories (~/Downloads, ~/Pictures, …) ---
+  # Bare niri runs no desktop environment, so nothing generates
+  # ~/.config/user-dirs.dirs on its own — Firefox downloads land in $HOME, the
+  # GTK file chooser and Nautilus have a bare sidebar, and screenshot tools have
+  # no Pictures default. This trims the default set (Templates/Publicshare
+  # dropped — unused under niri) and runs the generator at login.
+  environment.etc."xdg/user-dirs.defaults".text = ''
+    DESKTOP=Desktop
+    DOWNLOAD=Downloads
+    DOCUMENTS=Documents
+    MUSIC=Music
+    PICTURES=Pictures
+    VIDEOS=Videos
+  '';
+  # A oneshot bound to graphical-session.target (the target niri-session brings
+  # up — same hook swayidle uses). Before= makes the session wait for the dirs to
+  # exist before apps start. GTK/GLib reads user-dirs.dirs directly, so no env
+  # export is needed for the file to take effect.
+  systemd.user.services.xdg-user-dirs-update = {
+    description = "Create/update XDG user directories (~/Downloads, ~/Pictures, …)";
+    wantedBy = [ "graphical-session.target" ];
+    partOf = [ "graphical-session.target" ];
+    before = [ "graphical-session.target" ];
+    serviceConfig = {
+      Type = "oneshot";
+      ExecStart = "${pkgs.xdg-user-dirs}/bin/xdg-user-dirs-update";
+    };
+  };
+
+  # --- Bar + wallpaper (was spawn-at-startup in the shared niri config.kdl) ---
+  # The bar and wallpaper differ per host, so they live in nixos-config rather
+  # than the stowed niri config. Long-running user services bound to
+  # graphical-session.target (the target niri-session activates), same hook as
+  # xdg-user-dirs-update above.
+  systemd.user.services.yambar = {
+    description = "yambar status bar";
+    wantedBy = [ "graphical-session.target" ];
+    partOf = [ "graphical-session.target" ];
+    after = [ "graphical-session.target" ];
+    serviceConfig = {
+      ExecStart = "${pkgs.yambar}/bin/yambar";
+      Restart = "on-failure";
+    };
+  };
+
+  systemd.user.services.swaybg = {
+    description = "swaybg wallpaper";
+    wantedBy = [ "graphical-session.target" ];
+    partOf = [ "graphical-session.target" ];
+    after = [ "graphical-session.target" ];
+    serviceConfig = {
+      # Solid color (the old shared config's --image path pointed at
+      # /home/henz, kusanagi's user, so enzo never had a valid image). Swap in
+      # an enzo-local image path here if desired.
+      ExecStart = "${pkgs.swaybg}/bin/swaybg --color '#24273a'";
+      Restart = "on-failure";
+    };
+  };
+
   # --- User: desktop groups (niri essentials) ---
   users.users.hwebs.extraGroups = [
     "audio"