@@ -0,0 +1,196 @@
+inputs:
+with inputs;
+let
+  # System types to support.
+  supportedSystems = [
+    "x86_64-linux"
+    "aarch64-linux"
+    "aarch64-darwin"
+  ];
+
+  # Helper function to generate an attrset '{ x86_64-linux = f "x86_64-linux"; ... }'.
+  forAllSystems = nixpkgs.lib.genAttrs supportedSystems;
+
+  overlayedNixpkgs =
+    system:
+    import nixpkgs {
+      inherit system;
+      config = {
+        allowUnfree = true;
+      };
+      overlays = [
+        (self: super: {
+          unstable = import nixpkgs-unstable { inherit system; };
+          personal = import ./packages/overlay.nix self super;
+        })
+      ];
+    };
+
+  nixosSystem =
+    {
+      system,
+      modules,
+      ...
+    }@args:
+    nixpkgs.lib.nixosSystem (
+      {
+        inherit system;
+        pkgs = overlayedNixpkgs system;
+        inherit modules;
+        specialArgs = {
+          inherit pkgsUnstable;
+          inherit inputs;
+        };
+      }
+      // args
+    );
+
+  mkHomeConfiguration =
+    { modules, system }:
+    home-manager.lib.homeManagerConfiguration {
+      pkgs = import nixpkgs {
+        inherit system;
+        overlays = [
+          agenix.overlays.default
+          scriptura.overlays.default
+          (self: super: {
+            personal = import ./packages/overlay.nix self super;
+            iqan = iqan.packages.${system}.iqan;
+          })
+        ];
+      };
+
+      extraSpecialArgs = {
+        inherit inputs;
+      };
+
+      modules = [
+        nixvim.homeModules.nixvim
+        scriptura.homeModules.scriptura
+      ]
+      ++ modules;
+    };
+in
+{
+  nixosConfigurations = {
+    # build with `nixos-rebuild build-image --image-variant iso-installer`
+    minimal-iso = nixosSystem {
+      system = "x86_64-linux";
+      modules = [ ./system/hosts/installer.nix ];
+    };
+    prefect = nixosSystem {
+      system = "x86_64-linux";
+      modules = (
+        with nixos-hardware.nixosModules;
+        [
+          ./system/hosts/prefect.nix
+          common-cpu-amd-pstate
+          common-cpu-amd-zenpower
+          common-pc-ssd
+          common-pc
+          "${nixos-hardware}/common/gpu/nvidia/ada-lovelace"
+        ]
+      );
+    };
+    r5 = nixosSystem {
+      system = "aarch64-linux";
+      modules = [
+        agenix.nixosModules.default
+        srvos.nixosModules.server
+        nanopi.nixosModules.r5s
+        ./system/hosts/r5.nix
+        ./system/hosts/r5-hardware.nix
+      ];
+    };
+    hasel = nixosSystem {
+      system = "x86_64-linux";
+      modules = [
+        srvos.nixosModules.server
+        agenix.nixosModules.default
+        ./packages/modules/nixos/laminar.nix
+        ./packages/modules/nixos/bark.nix
+        ./system/hosts/hasel.nix
+      ];
+    };
+    ulme = nixosSystem {
+      system = "x86_64-linux";
+      modules = [
+        srvos.nixosModules.server
+        agenix.nixosModules.default
+        ./packages/modules/nixos/bark.nix
+        ./system/hosts/ulme.nix
+      ];
+    };
+  };
+  darwinConfigurations = {
+    marvin = darwin.lib.darwinSystem {
+      system = "aarch64-darwin";
+      modules = [
+        srvos.darwinModules.desktop
+        ./system/hosts/marvin.nix
+      ];
+    };
+  };
+  homeConfigurations = {
+    "alin@marvin" = mkHomeConfiguration {
+      system = "aarch64-darwin";
+      modules = [
+        ./user/hosts/marvin.nix
+        ./private/ssh.nix
+      ];
+    };
+    "alin@prefect" = mkHomeConfiguration {
+      system = "x86_64-linux";
+      modules = [
+        ./user/hosts/prefect.nix
+        ./private/ssh.nix
+      ];
+    };
+    "alin@r5" = mkHomeConfiguration {
+      system = "aarch64-linux";
+      modules = [
+        ./user/hosts/r5.nix
+      ];
+    };
+    "alin@hasel" = mkHomeConfiguration {
+      system = "x86_64-linux";
+      modules = [
+        ./user/hosts/server.nix
+        {
+          home.stateVersion = "26.05";
+        }
+      ];
+    };
+    "alin@ulme" = mkHomeConfiguration {
+      system = "x86_64-linux";
+      modules = [
+        ./user/hosts/server.nix
+        {
+          home.stateVersion = "26.05";
+        }
+      ];
+    };
+
+  };
+
+  devShells = forAllSystems (
+    system:
+    let
+      pkgs = import nixpkgs { inherit system; };
+    in
+    {
+      default = pkgs.mkShellNoCC {
+        packages = with pkgs; [
+          just
+          nh
+          home-manager
+          nixos-rebuild
+          nixos-option
+        ];
+      };
+      secrets = pkgs.mkShellNoCC {
+        packages = [ agenix.packages.${system}.default ];
+      };
+    }
+  );
+}