home: add automatic home-manager cleanup service

user/home-manager.nix

@@ -0,0 +1,28 @@
+{ pkgs, lib, ... }:
+{
+  programs.home-manager.enable = true;
+
+  systemd.user.services.home-manager-expire = {
+    Unit = {
+      Description = "Remove old home-manager generations";
+    };
+    Service = {
+      Type = "oneshot";
+      ExecStart = pkgs.writeShellScript "home-manager-expire" ''
+        ${lib.getExe pkgs.home-manager} expire-generations 7d
+      '';
+    };
+  };
+  systemd.user.timers.home-manager-expire = {
+    Unit = {
+      Description = "Remove old home-manager generations";
+    };
+    Timer = {
+      OnCalendar = "daily";
+      Unit = "home-manager-expire.service";
+    };
+    Install = {
+      WantedBy = [ "timers.target" ];
+    };
+  };
+}

user/home.nix

@@ -9,6 +9,7 @@
 {
   imports = [
     ./dummy.nix
+    ./home-manager.nix
     ./waybar
     ./helix.nix
     ./kakoune
@@ -58,8 +59,6 @@
   home.username = "lelgenio";
   home.homeDirectory = "/home/lelgenio";
 
-  # Let Home Manager install and manage itself.
-  programs.home-manager.enable = true;
   home.packages = with pkgs; [
     terminal