feat: initial macos setup

flake.nix

@@ -9,6 +9,12 @@
       inputs.nixpkgs.follows = "nixpkgs";
     };
 
+    # macOS system management (paired with nixpkgs 26.05).
+    nix-darwin = {
+      url = "github:nix-darwin/nix-darwin/nix-darwin-26.05";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+
     globalprotect-openconnect.url = "github:yuezk/GlobalProtect-openconnect";
 
     plasma-manager = {
@@ -28,44 +34,62 @@
     };
   };
 
-  outputs = { self, nixpkgs, home-manager, globalprotect-openconnect, ... }@inputs: 
+  outputs = { self, nixpkgs, home-manager, nix-darwin, globalprotect-openconnect, ... }@inputs:
   let
-    system = "x86_64-linux";
+    linuxSystem = "x86_64-linux";
+
+    # Home Manager wiring shared by the NixOS (Linux) hosts.
+    # plasma-manager is Linux-only, so it lives here rather than in the
+    # darwin block below.
+    nixosHome = {
+      home-manager = {
+        useGlobalPkgs = true;
+        useUserPackages = true;
+        backupFileExtension = "backup";
+        users.alex = import ./home/alex;
+        extraSpecialArgs = { inherit inputs; isDarwin = false; };
+        sharedModules = [ inputs.plasma-manager.homeModules.plasma-manager ];
+      };
+    };
   in {
     nixosConfigurations = {
-      
-      # To add a new machine, duplicate this block and change the name
+
+      # To add a new Linux machine, duplicate this block and change the name.
       whitegrizzly = nixpkgs.lib.nixosSystem {
-        inherit system;
-        specialArgs = { inherit inputs; }; 
+        system = linuxSystem;
+        specialArgs = { inherit inputs; };
         modules = [
           ./hosts/whitegrizzly
           home-manager.nixosModules.home-manager
-          {
-            home-manager = {
-              useGlobalPkgs = true;
-              useUserPackages = true;
-              users.alex = import ./home/alex;
-              extraSpecialArgs = { inherit inputs; };
-              sharedModules = [ inputs.plasma-manager.homeModules.plasma-manager ];
-            };
-          }
+          nixosHome
         ];
       };
 
       oreo = nixpkgs.lib.nixosSystem {
-        inherit system;
-        specialArgs = { inherit inputs; }; 
+        system = linuxSystem;
+        specialArgs = { inherit inputs; };
         modules = [
           ./hosts/oreo
           home-manager.nixosModules.home-manager
+          nixosHome
+        ];
+      };
+    };
+
+    darwinConfigurations = {
+
+      seasoned = nix-darwin.lib.darwinSystem {
+        specialArgs = { inherit inputs; };
+        modules = [
+          ./hosts/seasoned
+          home-manager.darwinModules.home-manager
           {
             home-manager = {
               useGlobalPkgs = true;
               useUserPackages = true;
+              backupFileExtension = "backup";
               users.alex = import ./home/alex;
-              extraSpecialArgs = { inherit inputs; };
-              sharedModules = [ inputs.plasma-manager.homeModules.plasma-manager ];
+              extraSpecialArgs = { inherit inputs; isDarwin = true; };
             };
           }
         ];