Make system architecture per-host instead of global constant

flake.nix

@@ -3,7 +3,7 @@
 
   inputs = {
     # Core
-    nixpkgs.url = "github:nixos/nixpkgs/nixos-24.11";
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-25.11";
     nixpkgs-unstable.url = "github:nixos/nixpkgs/nixos-unstable";
 
     # Flakes
@@ -11,7 +11,7 @@
 
     # Home Manager
     home-manager = {
-      url = "github:nix-community/home-manager/release-24.11";
+      url = "github:nix-community/home-manager/release-25.11";
       inputs.nixpkgs.follows = "nixpkgs";
     };
 
@@ -30,23 +30,55 @@
 
   outputs = { self, nixpkgs, nixpkgs-unstable, flake-utils, home-manager, sops-nix, disko }:
     let
-      system = "x86_64-linux";
+      # Helper to build per-host pkgs for a given system string
-
+      mkPkgs = system: import nixpkgs {
-      pkgs = import nixpkgs {
         inherit system;
         config.allowUnfree = true;
       };
 
-      pkgs-unstable = import nixpkgs-unstable {
+      mkPkgsUnstable = system: import nixpkgs-unstable {
         inherit system;
         config.allowUnfree = true;
       };
 
-      # Utility to overlay unstable packages
+      # Utility to overlay unstable packages (takes system as arg)
-      overlayUnstable = final: prev: {
+      mkOverlayUnstable = system:
-        unstable = pkgs-unstable;
+        final: prev: { unstable = mkPkgsUnstable system; };
+
+      # Helper that builds a full NixOS configuration for a given host + arch
+      mkNixosSystem = { system, hostModule }: nixpkgs.lib.nixosSystem {
+        inherit system;
+
+        specialArgs = {
+          inherit sops-nix disko;
+          pkgs-unstable = mkPkgsUnstable system;
         };
 
+        modules = [
+          (mkOverlayUnstable system)
+          sops-nix.nixosModules.sops
+          disko.nixosModules.disko
+
+          hostModule
+          ./nixos/default.nix
+
+          home-manager.nixosModules.home-manager
+          {
+            home-manager.useGlobalPkgs = true;
+            home-manager.useUserPackages = true;
+            home-manager.extraSpecialArgs = {
+              inherit sops-nix;
+              pkgs-unstable = mkPkgsUnstable system;
+            };
+            home-manager.users.youruser = import ./home/default.nix;
+          }
+        ];
+      };
+
+      # Default system for devShell and standalone home-manager
+      defaultSystem = "x86_64-linux";
+      pkgs = mkPkgs defaultSystem;
+
     in {
 
       # ============================================
@@ -55,67 +87,23 @@
 
       nixosConfigurations = {
 
-        # Example: Laptop configuration
+        # x86_64 laptop (most common)
-        laptop = nixpkgs.lib.nixosSystem {
+        laptop = mkNixosSystem {
-          inherit system;
+          system = "x86_64-linux";
-
+          hostModule = ./hosts/laptop/default.nix;
-          specialArgs = {
-            inherit sops-nix disko;
-            pkgs-unstable = pkgs-unstable;
         };
 
-          modules = [
+        # x86_64 server
-            overlayUnstable
+        server = mkNixosSystem {
-            sops-nix.nixosModules.sops
+          system = "x86_64-linux";
-            disko.nixosModules.disko
+          hostModule = ./hosts/server/default.nix;
-
-            # Machine-specific config
-            ./hosts/laptop/default.nix
-
-            # Shared system modules
-            ./nixos/default.nix
-
-            # Home Manager integration
-            home-manager.nixosModules.home-manager
-            {
-              home-manager.useGlobalPkgs = true;
-              home-manager.useUserPackages = true;
-              home-manager.extraSpecialArgs = {
-                inherit sops-nix pkgs-unstable;
-              };
-              home-manager.users.youruser = import ./home/default.nix;
-            }
-          ];
         };
 
-        # Example: Server configuration
+        # Example: ARM64 host (e.g. Raspberry Pi 4, Apple Silicon VM)
-        server = nixpkgs.lib.nixosSystem {
+        # laptop-arm = mkNixosSystem {
-          inherit system;
+        #   system = "aarch64-linux";
-
+        #   hostModule = ./hosts/laptop/default.nix;
-          specialArgs = {
+        # };
-            inherit sops-nix disko;
-            pkgs-unstable = pkgs-unstable;
-          };
-
-          modules = [
-            overlayUnstable
-            sops-nix.nixosModules.sops
-            disko.nixosModules.disko
-
-            ./hosts/server/default.nix
-            ./nixos/default.nix
-
-            home-manager.nixosModules.home-manager
-            {
-              home-manager.useGlobalPkgs = true;
-              home-manager.useUserPackages = true;
-              home-manager.extraSpecialArgs = {
-                inherit sops-nix pkgs-unstable;
-              };
-              home-manager.users.youruser = import ./home/default.nix;
-            }
-          ];
-        };
       };
 
       # ============================================
@@ -123,24 +111,38 @@
       # ============================================
 
       homeConfigurations = {
+        # x86_64 Linux
         "youruser@linux" = home-manager.lib.homeManagerConfiguration {
-          inherit pkgs;
+          pkgs = mkPkgs "x86_64-linux";
           extraSpecialArgs = {
-            pkgs-unstable = pkgs-unstable;
+            pkgs-unstable = mkPkgsUnstable "x86_64-linux";
             sops-nix = sops-nix;
           };
           modules = [
-            overlayUnstable
+            (mkOverlayUnstable "x86_64-linux")
             ./home/default.nix
           ];
         };
+
+        # aarch64 Linux (e.g. Raspberry Pi, ARM servers)
+        # "youruser@linux-arm" = home-manager.lib.homeManagerConfiguration {
+        #   pkgs = mkPkgs "aarch64-linux";
+        #   extraSpecialArgs = {
+        #     pkgs-unstable = mkPkgsUnstable "aarch64-linux";
+        #     sops-nix = sops-nix;
+        #   };
+        #   modules = [
+        #     (mkOverlayUnstable "aarch64-linux")
+        #     ./home/default.nix
+        #   ];
+        # };
       };
 
       # ============================================
       # Development Shell
       # ============================================
 
-      devShells.${system}.default = pkgs.mkShell {
+      devShells.${defaultSystem}.default = pkgs.mkShell {
         buildInputs = with pkgs; [
           nix
           nixpkgs-fmt
@@ -151,7 +153,7 @@
         ];
 
         shellHook = ''
-          echo "🔧 NixOS Configuration Development Shell"
+          echo "NixOS Configuration Development Shell"
           echo "Available commands:"
           echo "  - nix flake check              # Check flake validity"
           echo "  - nix flake show               # Show all outputs"
@@ -165,7 +167,7 @@
       # Installer Script
       # ============================================
 
-      apps.${system}.installer = {
+      apps.${defaultSystem}.installer = {
         type = "app";
         program = toString (pkgs.writeShellScript "installer" ''
           set -e