restructuring

configurations/any.nix

@@ -1,18 +1,15 @@
+# Host: "default" (device: minimal)
+#
+# The host record lives in configurations/default.nix; this file is only the
+# module body. `xlib` (identity, dirs, helpers) arrives as a module argument.
 {
-  deviceType = "minimal";
-  modules = [
-    (
-      {
-        inputs,
-        ...
-      }:
-      {
-        imports = [
-          inputs.self.nixosModules.default
-        ];
-
-        system.stateVersion = "26.05";
-      }
-    )
+  inputs,
+  ...
+}:
+{
+  imports = [
+    inputs.self.nixosModules.default
   ];
+
+  system.stateVersion = "26.05";
 }

configurations/default.nix

@@ -1,18 +1,73 @@
 { inputs, ... }@flakeContext:
 let
+  lib = inputs.nixpkgs.lib;
   mkSystem = import ../lib/mkSystem.nix flakeContext;
+  xlibLib = import ../lib/xlib { inherit lib; };
+
+  # One record per host. The attribute name IS the hostname, so it is written
+  # exactly once; `hostname` is only needed where the attribute name is not
+  # the real hostname (the `default` entry).
+  #
+  #   device   device type, must be a key of `devices` in lib/xlib/device.nix
+  #   modules  module body for this host
+  hosts = {
+    default = {
+      hostname = "nixos";
+      device = "minimal";
+      modules = [ ./any.nix ];
+    };
+    atoridu = {
+      device = "primary";
+      modules = [ ./mini-pc.nix ];
+    };
+    rydiwo = {
+      device = "secondary";
+      modules = [ ./mini-laptop.nix ];
+    };
+    otreca = {
+      device = "vds";
+      modules = [ ./vds.nix ];
+    };
+    sapphira = {
+      device = "server";
+      modules = [ ./server.nix ];
+    };
+    wsl = {
+      device = "wsl";
+      modules = [ ./wsl.nix ];
+    };
+  };
+
+  mkHost =
+    name:
+    {
+      device,
+      modules,
+      hostname ? name,
+      ...
+    }:
+    let
+      xlib = xlibLib.mkXlib {
+        inherit hostname;
+        type = device;
+      };
+    in
+    {
+      inherit xlib;
+      system = mkSystem { inherit xlib modules; };
+    };
 in
 {
-  nixosConfigurations = {
-    default = mkSystem (import ./any.nix); # default
-    atoridu = mkSystem (import ./mini-pc.nix); # atoridu
-    rydiwo = mkSystem (import ./mini-laptop.nix); # rydiwo
-    otreca = mkSystem (import ./vds.nix); # vds
-    sapphira = mkSystem (import ./server.nix); # sapphira
-    wsl = mkSystem (import ./wsl.nix); # wsl
-  };
+  nixosConfigurations = lib.mapAttrs' (
+    name: spec: lib.nameValuePair name (mkHost name spec).system
+  ) hosts;
+
+  # Per-host xlib values, for code that lives outside the module system
+  # (deploy, overlays, pkgs).
+  xlib = lib.mapAttrs' (name: spec: lib.nameValuePair name (mkHost name spec).xlib) hosts;
+
   nixOnDroidConfigurations = {
-    epral = import ./mobile.nix flakeContext; # epral (Android via nix-on-droid)
+    epral = import ./mobile.nix flakeContext; # epral (Android device via nix-on-droid)
     # Alias so a plain `nix-on-droid switch` from a local clone
     # (~/.config/nix-on-droid) picks up the device config without `#epral`.
     default = import ./mobile.nix flakeContext;

configurations/mini-laptop.nix

@@ -1,41 +1,37 @@
+# Host: "rydiwo" (device: secondary)
+#
+# The host record lives in configurations/default.nix; this file is only the
+# module body. `xlib` (identity, dirs, helpers) arrives as a module argument.
 {
-  deviceType = "secondary";
-  hostname = "rydiwo";
-  modules = [
-    (
-      {
-        lib,
-        pkgs,
-        xlib,
-        inputs,
-        ...
-      }:
-      {
-        imports = with inputs; [
-          nixos-hardware.nixosModules.chuwi-minibook-x
-          ./hardware/mini-laptop.nix
-          self.nixosModules.default
-        ];
-
-        boot = {
-          kernelPackages = lib.mkDefault pkgs.linuxPackages_xanmod_stable;
-          loader = {
-            systemd-boot.enable = lib.mkDefault true;
-            efi.canTouchEfiVariables = lib.mkDefault true;
-          };
-        };
-
-        fileSystems = xlib.helpers.mkNtfsMount {
-          path = xlib.dirs.lamet-drive;
-          uuid = "DC76BD3576BD116E";
-          mask = "0000";
-        };
-
-        xlib.ssh.enable = true;
-        hardware.intel-gpu-tools.enable = true;
-
-        system.stateVersion = "26.05";
-      }
-    )
+  lib,
+  pkgs,
+  xlib,
+  inputs,
+  ...
+}:
+{
+  imports = with inputs; [
+    nixos-hardware.nixosModules.chuwi-minibook-x
+    ./hardware/mini-laptop.nix
+    self.nixosModules.default
   ];
+
+  boot = {
+    kernelPackages = lib.mkDefault pkgs.linuxPackages_xanmod_stable;
+    loader = {
+      systemd-boot.enable = lib.mkDefault true;
+      efi.canTouchEfiVariables = lib.mkDefault true;
+    };
+  };
+
+  fileSystems = xlib.helpers.mkNtfsMount {
+    path = xlib.dirs.lamet-drive;
+    uuid = "DC76BD3576BD116E";
+    mask = "0000";
+  };
+
+  host.ssh.enable = true;
+  hardware.intel-gpu-tools.enable = true;
+
+  system.stateVersion = "26.05";
 }

configurations/mini-pc.nix

@@ -1,83 +1,84 @@
+# Host: "atoridu" (device: primary)
+#
+# The host record lives in configurations/default.nix; this file is only the
+# module body. `xlib` (identity, dirs, helpers) arrives as a module argument.
 {
-  deviceType = "primary";
-  hostname = "atoridu";
-  modules = [
-    (
-      {
-        lib,
-        pkgs,
-        xlib,
-        inputs,
-        ...
-      }:
-      {
-        imports = with inputs; [
-          ./hardware/mini-pc.nix
-          ./disko/mini-pc.nix
-          ./hardware/logitech.nix
-          self.nixosModules.default
-        ];
-
-        fileSystems = lib.listToAttrs (
-          map (xlib.helpers.mkNtfsMount) [
-            {
-              path = xlib.dirs.therima-drive;
-              uuid = "C0A2DDEFA2DDEA44";
-              enable = false;
-            }
-            {
-              path = xlib.dirs.vetymae-drive;
-              uuid = "6408433908430A0E";
-              enable = false;
-            }
-            {
-              path = xlib.dirs.soptur-drive;
-              uuid = "C00C56E40C56D54E";
-              enable = false;
-            }
-          ]
-        );
-
-        boot = {
-          kernelPackages = lib.mkDefault pkgs.linuxPackages_xanmod_stable;
-          loader = {
-            systemd-boot.enable = lib.mkDefault true;
-            efi.canTouchEfiVariables = lib.mkDefault true;
-          };
-        };
-
-        services.xserver = {
-          videoDrivers = [
-            "amdgpu"
-          ];
-        };
-        services.pipewire = {
-          enable = lib.mkDefault true;
-          systemWide = true;
-          alsa.enable = false;
-          alsa.support32Bit = true;
-          pulse.enable = true;
-          jack.enable = true;
-          extraConfig.pipewire = {
-            "99-default.conf" = {
-              "context.properties" = {
-                "default.clock.rate" = 96000;
-                "default.clock.allowed-rates" = [
-                  44100
-                  48000
-                  96000
-                ];
-                "default.clock.quantum" = 1024;
-                "default.clock.min-quantum" = 256;
-                "default.clock.max-quantum" = 2048;
-              };
-            };
-          };
-        };
-        nixpkgs.config.pulseaudio = true;
-
-        system.stateVersion = "26.05";
-      }
-    )
+  lib,
+  pkgs,
+  xlib,
+  inputs,
+  ...
+}:
+{
+  imports = with inputs; [
+    ./hardware/mini-pc.nix
+    ./disko/mini-pc.nix
+    ./hardware/logitech.nix
+    self.nixosModules.default
   ];
+
+  # mkNtfsMount returns a `{ "<path>" = { ... }; }` attrset (the shape
+  # fileSystems itself wants), so several mounts are combined with
+  # mergeAttrsList — not listToAttrs, which would demand `name`/`value`.
+  #
+  # These three ntfs3 drives are intentionally left unmounted. The entries
+  # are kept commented out rather than deleted, so restoring a drive is a
+  # matter of uncommenting its block. `enable = false` would declare a drive
+  # without mounting it; dropping the field mounts it.
+  fileSystems = lib.mergeAttrsList (
+    map (xlib.helpers.mkNtfsMount) [
+      # {
+      #   path = xlib.dirs.therima-drive;
+      #   uuid = "C0A2DDEFA2DDEA44";
+      # }
+      # {
+      #   path = xlib.dirs.vetymae-drive;
+      #   uuid = "6408433908430A0E";
+      # }
+      # {
+      #   path = xlib.dirs.soptur-drive;
+      #   uuid = "C00C56E40C56D54E";
+      # }
+    ]
+  );
+
+  boot = {
+    kernelPackages = lib.mkDefault pkgs.linuxPackages_xanmod_stable;
+    loader = {
+      systemd-boot.enable = lib.mkDefault true;
+      efi.canTouchEfiVariables = lib.mkDefault true;
+    };
+  };
+
+  services.xserver = {
+    videoDrivers = [
+      "amdgpu"
+    ];
+  };
+  services.pipewire = {
+    enable = lib.mkDefault true;
+    systemWide = true;
+    alsa.enable = false;
+    alsa.support32Bit = true;
+    pulse.enable = true;
+    jack.enable = true;
+    extraConfig.pipewire = {
+      "99-default.conf" = {
+        "context.properties" = {
+          "default.clock.rate" = 96000;
+          "default.clock.allowed-rates" = [
+            44100
+            48000
+            96000
+          ];
+          "default.clock.quantum" = 1024;
+          "default.clock.min-quantum" = 256;
+          "default.clock.max-quantum" = 2048;
+        };
+      };
+    };
+  };
+  nixpkgs.config.pulseaudio = true;
+
+  system.stateVersion = "26.05";
 }

configurations/mobile.nix

@@ -9,6 +9,7 @@ let
   # (essentials, users.nix, home-manager, sops-nix, disko, grub2-themes)
   # and nixpkgs.overlays are skipped so it evaluates under nix-on-droid's
   # module system (class = "nixOnDroid").
+  xlib = import ../lib/xlib.nix { lib = inputs.nixpkgs.lib; };
   nixOnDroidModule =
     {
       lib,
@@ -21,11 +22,6 @@ let
         inputs.self.nixosModules.strict
       ];
 
-      xlib.device = {
-        type = "termux";
-        hostname = "epral";
-      };
-
       # Login shell. nix-on-droid writes /etc/passwd from user.shell on every
       # activation, so `chsh` is useless here — set it in nix instead.
       # (default is bashInteractive)
@@ -120,6 +116,13 @@ inputs.nix-on-droid.lib.nixOnDroidConfiguration {
     nixOnDroidModule
   ];
   extraSpecialArgs = {
-    deviceType = "termux";
+    # `xlib` is the same value shape NixOS hosts get (lib/mkSystem.nix);
+    # the hostname lives here because nixOnDroidConfigurations is keyed by
+    # both "epral" and the "default" alias, so it cannot come from the
+    # attribute name.
+    xlib = xlib.mkXlib {
+      hostname = "epral";
+      type = "termux";
+    };
   };
 }

configurations/server.nix

@@ -1,83 +1,79 @@
+# Host: "sapphira" (device: server)
+#
+# The host record lives in configurations/default.nix; this file is only the
+# module body. `xlib` (identity, dirs, helpers) arrives as a module argument.
 {
-  deviceType = "server";
-  hostname = "sapphira";
-  modules = [
-    (
-      {
-        lib,
-        pkgs,
-        xlib,
-        inputs,
-        ...
-      }:
-      {
-        imports = [
-          ./hardware/server.nix
-          inputs.self.nixosModules.default
-        ];
-
-        boot = {
-          # kernelPackages = pkgs.linuxPackages_xanmod_stable;
-          hardwareScan = true;
-          loader = {
-            systemd-boot.enable = lib.mkDefault true;
-            efi.canTouchEfiVariables = lib.mkDefault true;
-          };
-        };
-
-        hardware = {
-          bluetooth.enable = true;
-          graphics = {
-            enable = true;
-            extraPackages = with pkgs; [
-              intel-media-driver
-              intel-ocl
-              intel-vaapi-driver
-            ];
-          };
-          intel-gpu-tools.enable = true;
-        };
-
-        fileSystems =
-          (xlib.helpers.mkExfatMount {
-            path = xlib.dirs.archive-drive;
-            label = "archive";
-          })
-          // (xlib.helpers.mkExfatMount {
-            path = xlib.dirs.mobile-drive;
-            uuid = "7EB1-DC99";
-          })
-          // (xlib.helpers.mkBindMount {
-            what = xlib.dirs.services-folder;
-            where = xlib.dirs.services-mnt-folder;
-          })
-          // {
-            # External drive
-            "${xlib.dirs.server-home}" = {
-              device = "/dev/disk/by-uuid/37e53ebc-5343-a94d-9fe2-0ca39e13a8de";
-              fsType = "ext4";
-            };
-          };
-
-        systemd.tmpfiles.rules = [
-          "z ${xlib.dirs.services-mnt-folder} 0777 root root -"
-        ];
-
-        xlib.ssh.enable = true;
-
-        networking = {
-          networkmanager.enable = true;
-          firewall.enable = false;
-          # nameservers = [
-          #   "192.168.1.1"
-          #   "127.0.0.1"
-          # ];
-        };
-
-        system = {
-          stateVersion = "25.05";
-        };
-      }
-    )
+  lib,
+  pkgs,
+  xlib,
+  inputs,
+  ...
+}:
+{
+  imports = [
+    ./hardware/server.nix
+    inputs.self.nixosModules.default
   ];
+
+  boot = {
+    # kernelPackages = pkgs.linuxPackages_xanmod_stable;
+    hardwareScan = true;
+    loader = {
+      systemd-boot.enable = lib.mkDefault true;
+      efi.canTouchEfiVariables = lib.mkDefault true;
+    };
+  };
+
+  hardware = {
+    bluetooth.enable = true;
+    graphics = {
+      enable = true;
+      extraPackages = with pkgs; [
+        intel-media-driver
+        intel-ocl
+        intel-vaapi-driver
+      ];
+    };
+    intel-gpu-tools.enable = true;
+  };
+
+  fileSystems =
+    (xlib.helpers.mkExfatMount {
+      path = xlib.dirs.archive-drive;
+      label = "archive";
+    })
+    // (xlib.helpers.mkExfatMount {
+      path = xlib.dirs.mobile-drive;
+      uuid = "7EB1-DC99";
+    })
+    // (xlib.helpers.mkBindMount {
+      what = xlib.dirs.services-folder;
+      where = xlib.dirs.services-mnt-folder;
+    })
+    // {
+      # External drive
+      "${xlib.dirs.server-home}" = {
+        device = "/dev/disk/by-uuid/37e53ebc-5343-a94d-9fe2-0ca39e13a8de";
+        fsType = "ext4";
+      };
+    };
+
+  systemd.tmpfiles.rules = [
+    "z ${xlib.dirs.services-mnt-folder} 0777 root root -"
+  ];
+
+  host.ssh.enable = true;
+
+  networking = {
+    networkmanager.enable = true;
+    firewall.enable = false;
+    # nameservers = [
+    #   "192.168.1.1"
+    #   "127.0.0.1"
+    # ];
+  };
+
+  system = {
+    stateVersion = "25.05";
+  };
 }

configurations/vds.nix

@@ -1,122 +1,117 @@
+# Host: "otreca" (device: vds)
+#
+# The host record lives in configurations/default.nix; this file is only the
+# module body. `xlib` (identity, dirs, helpers) arrives as a module argument.
 {
-  deviceType = "vds";
-  hostname = "otreca";
-  modules = [
-    (
-      {
-        config,
-        lib,
-        modulesPath,
-        pkgs,
-        xlib,
-        inputs,
-        ...
-      }:
-      {
-        imports = [
-          (modulesPath + "/installer/scan/not-detected.nix")
-          (modulesPath + "/profiles/qemu-guest.nix")
+  lib,
+  modulesPath,
+  pkgs,
+  xlib,
+  inputs,
+  ...
+}:
+{
+  imports = [
+    (modulesPath + "/installer/scan/not-detected.nix")
+    (modulesPath + "/profiles/qemu-guest.nix")
 
-          ./disko/vds.nix
-          ./hardware/vds.nix
+    ./disko/vds.nix
+    ./hardware/vds.nix
 
-          inputs.self.nixosModules.default
-        ];
-
-        boot = {
-          # kernelPackages = pkgs.linuxPackages_xanmod_stable;
-          hardwareScan = true;
-          loader = {
-            grub = {
-              enable = true;
-              device = "nodev";
-              useOSProber = false;
-              efiSupport = false;
-            };
-            systemd-boot.enable = lib.mkDefault false;
-          };
-          kernel.sysctl = {
-            "net.ipv4.tcp_syncookies" = 1;
-            "net.ipv4.tcp_max_syn_backlog" = 4096;
-            "net.ipv4.tcp_synack_retries" = 3;
-            "net.ipv4.tcp_syn_retries" = 3;
-          };
-        };
-
-        xlib.ssh.enable = true;
-        services.openssh.openFirewall = true;
-
-        services.tailscale = {
-          enable = true;
-          openFirewall = true;
-        };
-        networking = {
-          nameservers = [
-            "1.1.1.1"
-            "8.8.8.8"
-          ];
-          networkmanager.enable = true;
-          tempAddresses = "disabled";
-          dhcpcd = {
-            enable = true;
-            IPv6rs = false;
-          };
-          firewall = {
-            enable = true;
-            allowPing = true;
-          };
-          nftables = {
-            enable = true;
-            ruleset = ''
-              table inet filter {
-                chain input {
-                  type filter hook input priority 0;
-
-                  # loopback
-                  iif lo accept
-
-                  # уже установленные
-                  ct state established,related accept
-
-                  # РЕЖЕМ SYN СРАЗУ
-                  tcp flags syn tcp dport {80,443} limit rate 20/second burst 40 packets accept
-                  tcp flags syn tcp dport {80,443} drop
-
-                  # остальное по необходимости
-                }
-              }
-            '';
-          };
-          enableIPv6 = false;
-          interfaces.ens3 = {
-            useDHCP = true;
-            # ipv4.addresses = [
-            #   {
-            #     address = "31.57.158.109";
-            #     prefixLength = 24;
-            #   }
-            # ];
-            # ipv6.addresses = [
-            #   {
-            #     address = "2a13:7c00:6:102:f816:3eff:fe91:6b9e";
-            #     prefixLength = 64;
-            #   }
-            # ];
-          };
-          # defaultGateway = {
-          #   address = "31.57.158.1";
-          #   interface = "ens3";
-          # };
-          # defaultGateway6 = {
-          #   address = "2a13:7c00:6:102::1";
-          #   interface = "ens3";
-          # };
-        };
-
-        system = {
-          stateVersion = "25.05";
-        };
-      }
-    )
+    inputs.self.nixosModules.default
   ];
+
+  boot = {
+    # kernelPackages = pkgs.linuxPackages_xanmod_stable;
+    hardwareScan = true;
+    loader = {
+      grub = {
+        enable = true;
+        device = "nodev";
+        useOSProber = false;
+        efiSupport = false;
+      };
+      systemd-boot.enable = lib.mkDefault false;
+    };
+    kernel.sysctl = {
+      "net.ipv4.tcp_syncookies" = 1;
+      "net.ipv4.tcp_max_syn_backlog" = 4096;
+      "net.ipv4.tcp_synack_retries" = 3;
+      "net.ipv4.tcp_syn_retries" = 3;
+    };
+  };
+
+  host.ssh.enable = true;
+  services.openssh.openFirewall = true;
+
+  services.tailscale = {
+    enable = true;
+    openFirewall = true;
+  };
+  networking = {
+    nameservers = [
+      "1.1.1.1"
+      "8.8.8.8"
+    ];
+    networkmanager.enable = true;
+    tempAddresses = "disabled";
+    dhcpcd = {
+      enable = true;
+      IPv6rs = false;
+    };
+    firewall = {
+      enable = true;
+      allowPing = true;
+    };
+    nftables = {
+      enable = true;
+      ruleset = ''
+        table inet filter {
+          chain input {
+            type filter hook input priority 0;
+
+            # loopback
+            iif lo accept
+
+            # уже установленные
+            ct state established,related accept
+
+            # РЕЖЕМ SYN СРАЗУ
+            tcp flags syn tcp dport {80,443} limit rate 20/second burst 40 packets accept
+            tcp flags syn tcp dport {80,443} drop
+
+            # остальное по необходимости
+          }
+        }
+      '';
+    };
+    enableIPv6 = false;
+    interfaces.ens3 = {
+      useDHCP = true;
+      # ipv4.addresses = [
+      #   {
+      #     address = "31.57.158.109";
+      #     prefixLength = 24;
+      #   }
+      # ];
+      # ipv6.addresses = [
+      #   {
+      #     address = "2a13:7c00:6:102:f816:3eff:fe91:6b9e";
+      #     prefixLength = 64;
+      #   }
+      # ];
+    };
+    # defaultGateway = {
+    #   address = "31.57.158.1";
+    #   interface = "ens3";
+    # };
+    # defaultGateway6 = {
+    #   address = "2a13:7c00:6:102::1";
+    #   interface = "ens3";
+    # };
+  };
+
+  system = {
+    stateVersion = "25.05";
+  };
 }

configurations/wsl.nix

@@ -1,44 +1,39 @@
+# Host: "wsl" (device: wsl)
+#
+# The host record lives in configurations/default.nix; this file is only the
+# module body. `xlib` (identity, dirs, helpers) arrives as a module argument.
 {
-  deviceType = "wsl";
-  hostname = "wsl";
-  modules = [
-    (
-      {
-        config,
-        lib,
-        pkgs,
-        modulesPath,
-        xlib,
-        inputs,
-        ...
-      }:
-      {
-        imports = [
-          inputs.nixos-wsl.nixosModules.default
-          inputs.self.nixosModules.default
-        ];
-
-        hardware = {
-          graphics.enable = true;
-        };
-
-        networking = {
-          firewall = {
-            enable = false;
-            allowPing = true;
-          };
-          enableIPv6 = true;
-        };
-
-        wsl = {
-          enable = true;
-          startMenuLaunchers = true;
-          useWindowsDriver = true;
-          defaultUser = config.xlib.device.username;
-        };
-
-        system.stateVersion = "24.11";
-      }
-    )
+  lib,
+  modulesPath,
+  pkgs,
+  xlib,
+  inputs,
+  ...
+}:
+{
+  imports = [
+    inputs.nixos-wsl.nixosModules.default
+    inputs.self.nixosModules.default
   ];
+
+  hardware = {
+    graphics.enable = true;
+  };
+
+  networking = {
+    firewall = {
+      enable = false;
+      allowPing = true;
+    };
+    enableIPv6 = true;
+  };
+
+  wsl = {
+    enable = true;
+    startMenuLaunchers = true;
+    useWindowsDriver = true;
+    defaultUser = xlib.device.username;
+  };
+
+  system.stateVersion = "24.11";
 }

deploy/default.nix

@@ -6,7 +6,9 @@ let
       path = inputs.deploy-rs.lib.x86_64-linux.activate.nixos inputs.self.nixosConfigurations.${hostname};
     };
   };
-  user = "${inputs.self.nixosConfigurations.default.config.xlib.device.username}";
+  # Login user for every deploy target. Read from the hoisted xlib instead of
+  # digging through a built NixOS configuration.
+  user = "${inputs.self.xlib.default.device.username}";
   server = "sapphira";
   vds = "otreca";
   mini-laptop = "rydiwo";

home/home.nix

@@ -53,11 +53,7 @@ let
             imports = [
               (./. + "/${xlib.device.type}.nix")
             ];
-            headless = builtins.elem xlib.device.type [
-              "server"
-              "vds"
-              "wsl"
-            ];
+            headless = xlib.isHeadless;
           };
         };
         sharedModules = [

lib/mkSystem.nix

@@ -2,26 +2,28 @@
   inputs,
   ...
 }:
+# Builds a NixOS system from a host record.
+#
+# `xlib` is the pure host value (lib/xlib.nix `mkXlib`) built in
+# configurations/default.nix. It is handed to every module as the `xlib`
+# argument, so modules read plain `xlib.*` data instead of `config.xlib.*`
+# and the host record stays the single source of truth.
 {
-  deviceType,
-  hostname ? null,
+  xlib,
   modules ? [ ],
   system ? "x86_64-linux",
+  ...
 }:
 let
   lib = inputs.nixpkgs.lib;
 in
 lib.nixosSystem {
-  inherit system;
-  modules = modules ++ [
-    {
-      xlib.device = {
-        type = deviceType;
-      }
-      // lib.optionalAttrs (hostname != null) { inherit hostname; };
-    }
-  ];
+  inherit
+    system
+    modules
+    ;
   specialArgs = {
-    inherit deviceType inputs;
+    inherit inputs;
+    inherit xlib;
   };
 }

lib/xlib/default.nix

@@ -0,0 +1,66 @@
+# Pure host library: no module system involved.
+#
+# Aggregates the four concerns a host record is built from:
+#   device.nix   identity + capability flags from the device type
+#   dirs.nix     well-known paths, derived from username
+#   helpers.nix  pure helper functions shared by modules
+#
+# `mkXlib` is called in flake-level code (configurations/default.nix) and
+# handed to every module as the `xlib` argument via lib/mkSystem.nix, so
+# modules read plain `xlib.*` values instead of `config.xlib.*` and nothing in
+# xlib can be overridden per host — the host record is the only place to
+# change it.
+{
+  lib,
+  ...
+}:
+let
+  inherit (import ./device.nix { inherit lib; })
+    devices
+    mkDevice
+    ;
+
+  # dirs.nix is itself a function of `username`, not an attrset.
+  mkDirs = import ./dirs.nix;
+
+  helpers = (import ./helpers.nix { inherit lib; });
+in
+{
+  inherit
+    devices
+    helpers
+    mkDevice
+    mkDirs
+    ;
+
+  # Full host record: identity + capability flags + well-known paths +
+  # shared helpers.
+  mkXlib =
+    {
+      hostname,
+      type,
+      username ? "oqyude",
+    }:
+    let
+      device = mkDevice {
+        inherit
+          hostname
+          type
+          username
+          ;
+      };
+    in
+    {
+      device = {
+        inherit
+          hostname
+          type
+          username
+          ;
+      };
+      isDesktop = device.isDesktop;
+      isHeadless = device.isHeadless;
+      dirs = mkDirs username;
+      inherit helpers;
+    };
+}

lib/xlib/device.nix

@@ -0,0 +1,65 @@
+{
+  lib,
+  ...
+}:
+# Supported device types and the identity record built from one.
+#
+# Single source of truth for host identity: hostname, type, username and the
+# capability flags derived from the type. Replaces the old `lib.types.enum`
+# in modules/options.nix and the hand-written type lists in modules/default.nix
+# and home/home.nix.
+let
+  devices = {
+    minimal = {
+      desktop = false;
+      headless = false;
+    };
+    primary = {
+      desktop = true;
+      headless = false;
+    };
+    secondary = {
+      desktop = true;
+      headless = false;
+    };
+    server = {
+      desktop = false;
+      headless = true;
+    };
+    vds = {
+      desktop = false;
+      headless = true;
+    };
+    wsl = {
+      desktop = false;
+      headless = true;
+    };
+    termux = {
+      desktop = false;
+      headless = true;
+    };
+  };
+in
+{
+  inherit devices;
+
+  # Unknown device type fails here, at flake level, with the valid list.
+  mkDevice =
+    {
+      hostname,
+      type,
+      username ? "oqyude",
+    }:
+    let
+      capabilities = devices.${type} or (throw "xlib: unknown device type '${type}', expected one of ${lib.concatStringsSep ", " (builtins.attrNames devices)}");
+    in
+    {
+      inherit
+        hostname
+        type
+        username
+        ;
+      isDesktop = capabilities.desktop;
+      isHeadless = capabilities.headless;
+    };
+}

lib/xlib/dirs.nix

@@ -0,0 +1,34 @@
+# Well-known paths. Everything derives from `username`, which is why the
+# whole set can be computed outside the module system.
+username:
+let
+  user-home = "/home/${username}";
+  wsl-home = "/mnt/c/Users/${username}";
+  server-home = "${user-home}/External";
+  services-mnt-folder = "/mnt/services";
+in
+{
+  inherit
+    user-home
+    wsl-home
+    server-home
+    services-mnt-folder
+    ;
+
+  user-storage = "${user-home}/Storage";
+  wsl-storage = "${wsl-home}/Storage";
+  server-credentials = "${server-home}/Credentials/server";
+  storage = "${server-home}/Storage";
+  calibre-library = "${server-home}/Books-Library";
+  services-folder = "${server-home}/Services";
+  services-nodes-folder = "${services-mnt-folder}/nodes";
+  postgresql-folder = "${services-mnt-folder}/postgresql";
+  music-library = "${user-home}/Music";
+
+  archive-drive = "/mnt/archive";
+  lamet-drive = "/mnt/lamet";
+  mobile-drive = "/mnt/mobile";
+  therima-drive = "/mnt/therima";
+  vetymae-drive = "/mnt/vetymae";
+  soptur-drive = "/mnt/soptur";
+}

lib/xlib/helpers.nix

@@ -2,8 +2,11 @@
   lib,
   ...
 }:
-# Shared pure helper functions for module definitions.
-# Injected into every module via `xlib.helpers` (see options.nix).
+# Pure helper functions for module definitions.
+# Injected into every module via `xlib.helpers` (see default.nix).
+#
+# Defined in a `let` because they reference each other (mkTmpDirs uses
+# mkTmpfile, mkServiceStorage uses mkTmpDirs + mkSystemdBind).
 let
   # tmpfiles rule: "type dir mode user group -"
   mkTmpfile =

modules/containers/3x-ui.nix

@@ -7,7 +7,11 @@
 }:
 let
   panel = "${xlib.dirs.services-nodes-folder}/${xlib.device.hostname}/3x-ui";
-  certDomain = xlib.services."3x-ui".certDomain or null;
+  # Domain whose Let's Encrypt cert (at /var/lib/acme/<domain>/) gets mounted
+  # read-only into the 3x-ui container so the panel can terminate TLS itself.
+  # Null when 3x-ui serves plain HTTP and TLS is terminated by an upstream
+  # nginx.
+  certDomain = config.host."3x-ui".certDomain;
   certMounts =
     if certDomain == null then
       [ ]
@@ -28,94 +32,99 @@ let
   ];
   # VDS-only: nginx stream forwards host:443 → 127.0.0.1:15380 →
   # container:443, so Xray sees its REALITY inbound on port 443.
-  realityPorts = lib.optional xlib.services."3x-ui".reality443Forwarding "127.0.0.1:15380:443/tcp";
+  realityPorts = lib.optional config.host."3x-ui".reality443Forwarding "127.0.0.1:15380:443/tcp";
 in
 {
-  virtualisation = {
-    podman = {
-      enable = true;
-      autoPrune = {
+  # `host."3x-ui"` options are declared in modules/options.nix: they are set
+  # by modules/server and modules/vds, so this module cannot be the only place
+  # that knows they exist.
+  config = {
+    virtualisation = {
+      podman = {
         enable = true;
-        flags = [ "--all" ];
-      };
-      dockerCompat = true;
-    };
-    oci-containers = {
-      backend = "podman";
-      containers."3xui_app" = {
-        image = "ghcr.io/mhsanaei/3x-ui:latest";
-        environment = {
-          "XRAY_VMESS_AEAD_FORCED" = "false";
-          "XUI_ENABLE_FAIL2BAN" = "true";
-          "TZ" = "Europe/Moscow";
+        autoPrune = {
+          enable = true;
+          flags = [ "--all" ];
         };
-        volumes = [
-          "${panel}/cert/:/root/cert:rw"
-          "${panel}/db/:/etc/x-ui:rw"
-        ]
-        ++ certMounts;
-        log-driver = "journald";
-        # Adding a new inbound through the 3x-ui panel on a port outside
-        # the 14380-15379 range requires extending basePorts and rebuilding.
-        ports = basePorts ++ realityPorts;
+        dockerCompat = true;
       };
-    };
-  };
-
-  systemd = {
-    services = {
-      "podman-3xui_app" = {
-        serviceConfig.Restart = lib.mkOverride 90 "always";
-        partOf = [ "podman-compose-3x-ui-root.target" ];
-        wantedBy = [ "podman-compose-3x-ui-root.target" ];
-      };
-      "podman-update-3xui_app" = {
-        path = [ pkgs.podman ];
-        serviceConfig = {
-          Type = "oneshot";
-          TimeoutSec = 300;
+      oci-containers = {
+        backend = "podman";
+        containers."3xui_app" = {
+          image = "ghcr.io/mhsanaei/3x-ui:latest";
+          environment = {
+            "XRAY_VMESS_AEAD_FORCED" = "false";
+            "XUI_ENABLE_FAIL2BAN" = "true";
+            "TZ" = "Europe/Moscow";
+          };
+          volumes = [
+            "${panel}/cert/:/root/cert:rw"
+            "${panel}/db/:/etc/x-ui:rw"
+          ]
+          ++ certMounts;
+          log-driver = "journald";
+          # Adding a new inbound through the 3x-ui panel on a port outside
+          # the 14380-15379 range requires extending basePorts and rebuilding.
+          ports = basePorts ++ realityPorts;
         };
-        script = ''
-          podman pull ghcr.io/mhsanaei/3x-ui:latest
-          systemctl restart podman-3xui_app.service
-        '';
       };
     };
-    # Starts/stops together with all 3x-ui compose resources.
-    targets."podman-compose-3x-ui-root" = {
-      unitConfig.Description = "Root target generated by compose2nix.";
-      wantedBy = [ "multi-user.target" ];
-    };
-    # timers."podman-update-3xui_app" = {
-    #   wantedBy = [ "timers.target" ];
-    #   timerConfig = {
-    #     OnCalendar = "weekly";
-    #     Persistent = true;
-    #   };
-    # };
-    tmpfiles.rules = [
-      (xlib.helpers.mkTmpfile "d" xlib.dirs.services-mnt-folder "0755" "root" "root")
-      (xlib.helpers.mkTmpfile "d" xlib.dirs.services-nodes-folder "0755" "root" "root")
-      (xlib.helpers.mkTmpfile "d" "${xlib.dirs.services-nodes-folder}/${xlib.device.hostname}" "0755"
-        "root"
-        "root"
-      )
-      (xlib.helpers.mkTmpfile "d" panel "0755" "root" "root")
-      (xlib.helpers.mkTmpfile "d" "${panel}/db" "0755" "root" "root")
-      (xlib.helpers.mkTmpfile "d" "${panel}/cert" "0755" "root" "root")
-      # Relabel panel dir for SELinux so containers can access it.
-      (xlib.helpers.mkTmpfile "Z" panel "0755" "root" "root")
-    ];
-  };
 
-  # Enable container name DNS for all Podman networks.
-  networking.firewall = {
-    interfaces =
-      let
-        matchAll = if !config.networking.nftables.enable then "podman+" else "podman*";
-      in
-      {
-        "${matchAll}".allowedUDPPorts = [ 53 ];
+    systemd = {
+      services = {
+        "podman-3xui_app" = {
+          serviceConfig.Restart = lib.mkOverride 90 "always";
+          partOf = [ "podman-compose-3x-ui-root.target" ];
+          wantedBy = [ "podman-compose-3x-ui-root.target" ];
+        };
+        "podman-update-3xui_app" = {
+          path = [ pkgs.podman ];
+          serviceConfig = {
+            Type = "oneshot";
+            TimeoutSec = 300;
+          };
+          script = ''
+            podman pull ghcr.io/mhsanaei/3x-ui:latest
+            systemctl restart podman-3xui_app.service
+          '';
+        };
       };
+      # Starts/stops together with all 3x-ui compose resources.
+      targets."podman-compose-3x-ui-root" = {
+        unitConfig.Description = "Root target generated by compose2nix.";
+        wantedBy = [ "multi-user.target" ];
+      };
+      # timers."podman-update-3xui_app" = {
+      #   wantedBy = [ "timers.target" ];
+      #   timerConfig = {
+      #     OnCalendar = "weekly";
+      #     Persistent = true;
+      #   };
+      # };
+      tmpfiles.rules = [
+        (xlib.helpers.mkTmpfile "d" xlib.dirs.services-mnt-folder "0755" "root" "root")
+        (xlib.helpers.mkTmpfile "d" xlib.dirs.services-nodes-folder "0755" "root" "root")
+        (xlib.helpers.mkTmpfile "d" "${xlib.dirs.services-nodes-folder}/${xlib.device.hostname}" "0755"
+          "root"
+          "root"
+        )
+        (xlib.helpers.mkTmpfile "d" panel "0755" "root" "root")
+        (xlib.helpers.mkTmpfile "d" "${panel}/db" "0755" "root" "root")
+        (xlib.helpers.mkTmpfile "d" "${panel}/cert" "0755" "root" "root")
+        # Relabel panel dir for SELinux so containers can access it.
+        (xlib.helpers.mkTmpfile "Z" panel "0755" "root" "root")
+      ];
+    };
+
+    # Enable container name DNS for all Podman networks.
+    networking.firewall = {
+      interfaces =
+        let
+          matchAll = if !config.networking.nftables.enable then "podman+" else "podman*";
+        in
+        {
+          "${matchAll}".allowedUDPPorts = [ 53 ];
+        };
+    };
   };
 }

modules/default.nix

@@ -3,24 +3,15 @@ let
   # NixOS-only modules. termux runs nix-on-droid (its own module system,
   # class = "nixOnDroid"): options like services.*, users.*, sops.*, disko.*
   # and nixpkgs.overlays (flake assertion) do not exist there.
-  moduleArgs = config: {
-    inherit inputs;
-    xlib = config.xlib;
-  };
+  #
+  # `xlib` arrives as a module argument (see lib/mkSystem.nix) and is plain
+  # data, not a module option, so nothing here has to declare or set it.
   defaultModule =
     {
-      config,
-      deviceType,
       lib,
       xlib,
       ...
     }:
-    let
-      isDesktop = builtins.elem deviceType [
-        "primary"
-        "secondary"
-      ];
-    in
     {
       imports =
         with inputs;
@@ -37,33 +28,28 @@ let
           self.homeConfigurations.default.nixosModule # default homeConfigurations
           disko.nixosModules.disko # disko module
         ]
-        ++ lib.optional isDesktop ./desktop # desktop class: primary/secondary
+        # desktop class: primary/secondary
+        ++ lib.optional xlib.isDesktop ./desktop
         # device-type module dir; "minimal" has no extra modules
-        ++ lib.optional (!isDesktop && deviceType != "minimal") (./. + "/${deviceType}");
+        ++ lib.optional (!xlib.isDesktop && xlib.device.type != "minimal") (./. + "/${xlib.device.type}");
       nixpkgs.overlays = with inputs; [
         self.nixosOverlays.default
       ];
-      networking.hostName = lib.mkDefault config.xlib.device.hostname;
-      _module.args = moduleArgs config;
+      networking.hostName = lib.mkDefault xlib.device.hostname;
     };
   strictModule =
     {
-      config,
-      deviceType,
-      lib,
       xlib,
       ...
     }:
     {
-      imports = with inputs; [
+      imports = [
         # ./essentials
         # ./users.nix
         ./options.nix
-        (./. + "/${deviceType}")
+        (./. + "/${xlib.device.type}")
         # sops-nix.nixosModules.sops
       ];
-
-      _module.args = moduleArgs config;
     };
 in
 {

modules/essentials/ssh.nix

@@ -3,21 +3,31 @@
   lib,
   ...
 }:
-lib.mkIf config.xlib.ssh.enable {
-  services.openssh = {
-    enable = true;
-    allowSFTP = true;
-    openFirewall = lib.mkDefault false;
-    hostKeys = [
-      {
-        path = "/etc/ssh/id_ed25519";
-        type = "ed25519";
-      }
-    ];
-    settings = {
-      PasswordAuthentication = false;
-      PermitRootLogin = "yes";
-      UsePAM = true;
+{
+  options.host.ssh = {
+    enable = lib.mkOption {
+      type = lib.types.bool;
+      default = false;
+      description = "Enable the SSH server with the shared config below.";
+    };
+  };
+
+  config = lib.mkIf config.host.ssh.enable {
+    services.openssh = {
+      enable = true;
+      allowSFTP = true;
+      openFirewall = lib.mkDefault false;
+      hostKeys = [
+        {
+          path = "/etc/ssh/id_ed25519";
+          type = "ed25519";
+        }
+      ];
+      settings = {
+        PasswordAuthentication = false;
+        PermitRootLogin = "yes";
+        UsePAM = true;
+      };
     };
   };
 }

modules/options.nix

@@ -1,109 +1,41 @@
 {
-  config,
   lib,
   ...
 }:
-let
-  # Option factory for the xlib.dirs namespace
-  mkDir =
-    default: description:
-    lib.mkOption {
-      type = lib.types.str;
-      inherit default description;
-    };
-
-  helpers = import ../lib/xlib.nix { inherit lib; };
-in
+# Cross-module options: declared here, not in the module that reads them.
+#
+# An option belongs in this file when at least one context *sets* it while
+# another module *reads* it — the reader cannot be the only place that knows
+# the option exists. `modules/essentials/ssh.nix` does not belong here: it
+# declares and reads `host.ssh.enable` itself, within one module.
 {
-  options = {
-    xlib = {
-      device = {
-        type = lib.mkOption {
-          type = lib.types.enum [
-            "minimal"
-            "primary"
-            "secondary"
-            "server"
-            "vds"
-            "wsl"
-            "termux"
-          ];
-          default = "minimal";
-          description = "Type of device for this host.";
-        };
-        username = lib.mkOption {
-          type = lib.types.str;
-          default = "oqyude";
-          description = "Username for host.";
-        };
-        hostname = lib.mkOption {
-          type = lib.types.str;
-          default = "nixos";
-          description = "Hostname...";
-        };
-      };
-      ssh = {
-        enable = lib.mkOption {
-          type = lib.types.bool;
-          default = false;
-          description = "Enable SSH server with the standard config.";
-        };
-      };
-      dirs = {
-        user-home = mkDir "/home/${config.xlib.device.username}" "User home directory.";
-        user-storage = mkDir "${config.xlib.dirs.user-home}/Storage" "User storage directory.";
-        archive-drive = mkDir "/mnt/archive" "Archive drive mount point.";
-        lamet-drive = mkDir "/mnt/lamet" "Lamet drive mount point.";
-        mobile-drive = mkDir "/mnt/mobile" "Mobile drive mount point.";
-        therima-drive = mkDir "/mnt/therima" "Therima drive mount point.";
-        vetymae-drive = mkDir "/mnt/vetymae" "Vetymae drive mount point.";
-        soptur-drive = mkDir "/mnt/soptur" "Soptur drive mount point.";
-        wsl-home = mkDir "/mnt/c/Users/${config.xlib.device.username}" "WSL home directory.";
-        wsl-storage = mkDir "${config.xlib.dirs.wsl-home}/Storage" "WSL storage directory.";
-        server-home = mkDir "/home/${config.xlib.device.username}/External" "Server home directory.";
-        server-credentials = mkDir "${config.xlib.dirs.server-home}/Credentials/server" "Server credentials directory.";
-        storage = mkDir "${config.xlib.dirs.server-home}/Storage" "General storage directory.";
-        calibre-library = mkDir "${config.xlib.dirs.server-home}/Books-Library" "Calibre library directory.";
-        music-library = mkDir "${config.xlib.dirs.user-home}/Music" "Music library directory.";
-        services-folder = mkDir "${config.xlib.dirs.server-home}/Services" "All services folder.";
-        services-mnt-folder = mkDir "/mnt/services" "All services folder.";
-        services-nodes-folder = mkDir "${config.xlib.dirs.services-mnt-folder}/nodes" "All nodes folder.";
-        postgresql-folder = mkDir "${config.xlib.dirs.services-mnt-folder}/postgresql" "PostgreSQL service folder.";
-      };
-      helpers = lib.mkOption {
-        type = lib.types.anything;
-        default = helpers;
-        description = "Shared helper functions (see lib/xlib.nix).";
-      };
-      services."3x-ui" = {
-        # Domain whose Let's Encrypt cert (at /var/lib/acme/<domain>/)
-        # gets mounted read-only into the 3x-ui container so the panel
-        # can terminate TLS itself. Set null if 3x-ui serves plain HTTP
-        # and TLS is terminated by an upstream nginx.
-        certDomain = lib.mkOption {
-          type = lib.types.nullOr lib.types.str;
-          default = null;
-          example = "pubray1.zeroq.su";
-          description = ''
-            Domain whose LE cert should be mounted into the 3x-ui
-            container at /root/cert/fullchain.pem and key.pem.
-          '';
-        };
-        # Publish host:15380 → container:443. Only nodes that host an
-        # Xray REALITY inbound on container:443 need this (so nginx
-        # stream can forward TLS to Xray via 127.0.0.1:15380 while Xray
-        # itself sees incoming connections on its configured port 443).
-        # Set false on nodes that only run the 3x-ui panel.
-        reality443Forwarding = lib.mkOption {
-          type = lib.types.bool;
-          default = false;
-          description = ''
-            When true, publish host:15380 → container:443 so Xray
-            inside the container can serve REALITY on its real
-            configured port 443 (nginx stream forwards 443 → 15380).
-          '';
-        };
-      };
+  options.host."3x-ui" = {
+    # Domain whose Let's Encrypt cert (at /var/lib/acme/<domain>/)
+    # gets mounted read-only into the 3x-ui container so the panel
+    # can terminate TLS itself. Set null if 3x-ui serves plain HTTP
+    # and TLS is terminated by an upstream nginx.
+    certDomain = lib.mkOption {
+      type = lib.types.nullOr lib.types.str;
+      default = null;
+      example = "pubray1.zeroq.su";
+      description = ''
+        Domain whose LE cert should be mounted into the 3x-ui
+        container at /root/cert/fullchain.pem and key.pem.
+      '';
+    };
+    # Publish host:15380 → container:443. Only nodes that host an
+    # Xray REALITY inbound on container:443 need this (so nginx
+    # stream can forward TLS to Xray via 127.0.0.1:15380 while Xray
+    # itself sees incoming connections on its configured port 443).
+    # Set false on nodes that only run the 3x-ui panel.
+    reality443Forwarding = lib.mkOption {
+      type = lib.types.bool;
+      default = false;
+      description = ''
+        When true, publish host:15380 → container:443 so Xray
+        inside the container can serve REALITY on its real
+        configured port 443 (nginx stream forwards 443 → 15380).
+      '';
     };
   };
 }

modules/server/default.nix

@@ -50,7 +50,7 @@
   # there are other vhosts on the same port). Cert is still mounted in
   # case 3x-ui is later reconfigured to terminate TLS itself (e.g. for
   # direct node-API access); nginx doesn't have to use it.
-  xlib.services."3x-ui".certDomain = "x.zeroq.su";
+  host."3x-ui".certDomain = "x.zeroq.su";
   systemd.tmpfiles.rules = [
     (xlib.helpers.mkTmpfile "d" "/mnt" "0755" "root" "root")
     (xlib.helpers.mkTmpfile "d" xlib.dirs.services-mnt-folder "0755" "root" "root")

modules/users.nix

@@ -37,8 +37,6 @@ let
     );
 in
 {
-  xlib.device.username = "oqyude";
-
   users = {
     mutableUsers = false;
     users = {

modules/vds/default.nix

@@ -14,7 +14,7 @@
   ];
   # VDS hosts the public-facing Xray REALITY inbound on container:443,
   # fronted by nginx stream on host:443 → host:15380 → container:443.
-  xlib.services."3x-ui" = {
+  host."3x-ui" = {
     certDomain = "pubray1.zeroq.su";
     reality443Forwarding = true;
   };