restructured and optimized content

modules/nixos/core/system.nix

@@ -0,0 +1,91 @@
+{ inputs, outputs, config, lib, ... }:
+
+{
+  security = {
+    sudo.enable = true;
+    polkit.enable = true;
+  };
+
+  services = {
+    printing.enable = true;
+    acpid.enable = true;
+    upower.enable = true;
+  };
+
+  nix = {
+    # This will add each flake input as a registry
+    # To make nix3 commands consistent with your flake
+    registry = lib.mapAttrs (_: value: { flake = value; }) inputs;
+
+    # This will additionally add your inputs to the system's legacy channels
+    # Making legacy nix commands consistent as well, awesome!
+    nixPath = lib.mapAttrsToList (key: value: "${key}=${value.to.path}") config.nix.registry;
+
+
+    settings = {
+      # Enable flakes and new 'nix' command
+      experimental-features = "nix-command flakes";
+      substituters = [
+        "https://mirrors.ustc.edu.cn/nix-channels/store"
+        "https://nixos-cn.cachix.org"
+        "https://nix-community.cachix.org"
+        "https://cache.nixos.org/"
+      ];
+      trusted-public-keys = [
+        "nixos-cn.cachix.org-1:L0jEaL6w7kwQOPlLoCR3ADx+E3Q8SEFEcB9Jaibl0Xg="
+        "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
+      ];
+      trusted-users = [ "root" ];
+
+      # Enable local binary cache
+      keep-outputs = true;
+      keep-derivations = true;
+
+      max-jobs = "auto";
+      cores = 0;  # Use all available cores
+
+      # Deduplicate and optimize nix store during build
+      # auto-optimise-store = true;
+    };
+
+    gc = {
+      automatic = true;          # Enable automatic garbage collection
+      dates = "weekly";         # Execute garbage collection weekly
+      persistent = true;        # Keep settings after reboot
+      randomizedDelaySec = "15min";  # Add up to 15 minutes of random delay
+      options = "--delete-older-than 30d";  # Delete files older than 30 days
+    };
+
+    # Automatically run garbage collection whenever there is not enough space left
+    # Free up to 5GiB whenever there is less than 1GiB left:
+    extraOptions = ''
+      min-free = ${toString (1 * 1024 * 1024 * 1024)}
+      max-free = ${toString (5 * 1024 * 1024 * 1024)}
+    '';
+  };
+
+  nixpkgs = {
+    # You can add overlays here
+    overlays = [
+      # Add overlays your own flake exports (from overlays and pkgs dir):
+      outputs.overlays.additions
+      outputs.overlays.modifications
+      outputs.overlays.unstable-packages
+
+      # You can also add overlays exported from other flakes:
+      # neovim-nightly-overlay.overlays.default
+
+      # Or define it inline, for example:
+      # (final: prev: {
+      #   hi = final.hello.overrideAttrs (oldAttrs: {
+      #     patches = [ ./change-hello-to-hi.patch ];
+      #   });
+      # })
+    ];
+    # Configure your nixpkgs instance
+    config = {
+      # Disable if you don't want unfree packages
+      allowUnfree = true;
+    };
+  };
+}