nix-los/nixos/modules/yubikey.nix

{ pkgs, ... }:

{
  # Create the plugdev group (required for user-space USB access to YubiKey)
  users.groups.plugdev = {};

  # Enable PC/SC daemon — required for GPG smartcard (gpg --card-status) and YubiKey
  services.pcscd.enable = true;

  # udev rules so the YubiKey gets plugdev group ownership and correct permissions
  services.udev.packages = with pkgs; [
    yubikey-personalization
    libu2f-host
  ];

  # Give pcscd access to the YubiKey CCID USB interface (interface 1 on FIDO+CCID devices)
  services.udev.extraRules = ''
    SUBSYSTEM=="usb", ATTRS{idVendor}=="1050", ATTRS{idProduct}=="0406", MODE="0666"
  '';

  # CCID driver for smartcard access
  # NixOS's services.pcscd.plugins does not populate /var/lib/pcsc/drivers,
  # so we symlink the ifd-ccid.bundle from the ccid package directly.
  system.activationScripts.pcscdSetup = ''
    mkdir -p /var/lib/pcsc/drivers
    rm -rf /var/lib/pcsc/drivers/ifd-ccid.bundle 2>/dev/null || true
    ln -sf "${pkgs.ccid}/pcsc/drivers/ifd-ccid.bundle" /var/lib/pcsc/drivers/ifd-ccid.bundle
  '';

  # YubiKey management tools
  environment.systemPackages = with pkgs; [
    yubikey-manager          # ykman CLI
    yubikey-personalization  # ykpers / ykchalresp
    yubico-piv-tool          # PIV applet management
  ];
}