folded t480 hardware config into the flake to get rid of --impure

modules/hosts/t480/_hardware.nix

@@ -0,0 +1,27 @@
+# GENERATED FILE — do not edit by hand.
+#
+# Regenerate on the host itself with:  nix run .#sync-hardware
+#
+# Produced by `nixos-generate-config --show-hardware-config --no-filesystems`.
+# The --no-filesystems flag is deliberate: fileSystems and swapDevices are
+# declared by hand in ./disks.nix, so regenerating this file can never clobber
+# them or emit duplicates for whatever happened to be mounted at the time.
+#
+# Leading underscore keeps import-tree from auto-importing this as a
+# flake-parts module (its filter drops any path containing "/_"); it is
+# imported explicitly from ./default.nix instead.
+{ config, lib, pkgs, modulesPath, ... }:
+
+{
+  imports =
+    [ (modulesPath + "/installer/scan/not-detected.nix")
+    ];
+
+  boot.initrd.availableKernelModules = [ "xhci_pci" "nvme" "usb_storage" "usbhid" "sd_mod" ];
+  boot.initrd.kernelModules = [ ];
+  boot.kernelModules = [ "kvm-intel" ];
+  boot.extraModulePackages = [ ];
+
+  nixpkgs.hostPlatform = lib.mkDefault "x86_64-linux";
+  hardware.cpu.intel.updateMicrocode = lib.mkDefault config.hardware.enableRedistributableFirmware;
+}

modules/hosts/t480/default.nix

@@ -5,19 +5,10 @@
 }: {
   flake.nixosConfigurations.t480 = inputs.nixpkgs.lib.nixosSystem {
     modules = with self.nixosModules; [
-      # TODO: still importing by absolute path, so evaluating t480 requires
-      # --impure and picks up the hardware file of whatever machine you build
-      # from (on shadow, that means shadow's disk UUIDs — wrong but harmless
-      # until you actually deploy). Fix by running, ON THE T480 ITSELF:
-      #
-      #   nix run .#sync-hardware
-      #
-      # then create modules/hosts/t480/disks.nix (mirroring shadow's) and swap
-      # this line for `./_hardware.nix` + `t480Disks`. Cannot be done remotely:
-      # the hardware scan has to happen on the target machine.
-      /etc/nixos/hardware-configuration.nix
-      desktop
+      ./_hardware.nix
+      t480Disks
       t480Configuration
+      desktop
       # CPU microcode + integrated Intel GPU. The T480 also has an NVIDIA MX150;
       # to enable it in PRIME offload mode, swap gpuIntel for gpuNvidiaPrime
       # (which includes gpuIntel). Left on Intel-only by default to save power.

modules/hosts/t480/disks.nix

@@ -0,0 +1,19 @@
+{...}: {
+  flake.nixosModules.t480Disks = {...}: {
+    fileSystems = {
+      "/" = {
+        device = "/dev/disk/by-uuid/25316a27-6846-4922-8a45-854b9e40a19f";
+        fsType = "ext4";
+      };
+      "/boot" = {
+        device = "/dev/disk/by-uuid/562C-B760";
+        fsType = "vfat";
+        options = [ "fmask=0077" "dmask=0077" ];
+      };
+
+    };
+    swapDevices = [
+      { device = "/dev/disk/by-uuid/54e31e3a-af6a-4fd6-8101-4c168d3e482a"; }
+    ];
+  }; 
+}