temp add

common.nix

@@ -0,0 +1,63 @@
+# Shared system-level configuration for both NixOS and nix-darwin
+# Import this in both nixos/configuration.nix and darwin/configuration.nix
+{
+  inputs,
+  lib,
+  config,
+  pkgs,
+  ...
+}: {
+  # Shared Nix configuration
+  nix = let
+    flakeInputs = lib.filterAttrs (_: lib.isType "flake") inputs;
+  in {
+    settings = {
+      # Enable flakes and new 'nix' command
+      experimental-features = "nix-command flakes";
+      
+      # Opinionated: disable global registry
+      flake-registry = "";
+      
+      # Deduplicate and optimize nix store
+      auto-optimise-store = true;
+      
+      # Trusted users (useful for remote builds)
+      # trusted-users = [ "root" "@wheel" ];
+      
+      # Workaround for https://github.com/NixOS/nix/issues/9574
+      nix-path = config.nix.nixPath;
+    };
+
+    # Garbage collection
+    gc = {
+      automatic = true;
+      options = "--delete-older-than 7d";
+    };
+
+    # Opinionated: make flake registry and nix path match flake inputs
+    registry = lib.mapAttrs (_: flake: {inherit flake;}) flakeInputs;
+    nixPath = lib.mapAttrsToList (n: _: "${n}=flake:${n}") flakeInputs;
+  };
+
+  # Shared nixpkgs configuration
+  nixpkgs = {
+    overlays = [
+      inputs.self.overlays.additions
+      inputs.self.overlays.modifications
+      inputs.self.overlays.unstable-packages
+    ];
+    
+    config = {
+      allowUnfree = true;
+    };
+  };
+
+  # Shared environment packages
+  environment.systemPackages = with pkgs; [
+    vim
+    git
+    curl
+    wget
+  ];
+}
+