{ config, pkgs, username,inputs, lib, ... }:
{
  imports = [
    inputs.impermanence.nixosModules.impermanence
  ];

  # 系统启动时确保持久化目录存在
  system.activationScripts.persistent-dirs.text = ''
    mkdir -p /nix/persistent
  '';
  
  # 启用 tmpfs 作为根文件系统
  fileSystems."/" = lib.mkForce{
    device = "none";
    fsType = "tmpfs";
    options = [ "defaults" "size=2G" "mode=755" ];
  };

  # 将 /nix 存储在持久化分区
  fileSystems."/nix" = lib.mkForce{
    device = "/nix/persistent/nix";
    fsType = "btrfs";
    options = [ "compress-force=zstd" ];
  };

  # 建议的 fstab 配置
  fileSystems."/nix/persistent" = {
    device = "/dev/disk/by-label/nixos-persistent";  # 需要根据实际情况修改
    fsType = "btrfs";
    neededForBoot = true;
  };

  # 配置持久化存储
  environment.persistence."/nix/persistent" = {
    # 不在文件管理器中显示这些挂载点
    hideMounts = true;

    directories = [
      "/etc/nixos"  # NixOS 配置文件
      "/etc/NetworkManager/system-connections"  # 网络配置
      "/var/log"    # 系统日志
      "/var/lib"    # 系统数据
      "/root"       # root 用户目录
      "/.nix"
    ];

    files = [
      "/etc/machine-id"
      "/etc/ssh/ssh_host_ed25519_key"
      "/etc/ssh/ssh_host_ed25519_key.pub"
      "/etc/ssh/ssh_host_rsa_key"
      "/etc/ssh/ssh_host_rsa_key.pub"
    ];

    # 用户目录持久化配置
    users.${username} = {
      directories = [
        # 应用配置
        ".config"
        ".cache"
        ".local"
        ".ssh"
        ".gnupg"
        
        # 开发相关
        ".vscode"
        ".npm"
        ".cargo"

        "data"
        "doc"
      ];
      
      files = [
        ".bash_history"
        ".zsh_history"
        ".gitconfig"
      ];
    };
  };


}