# In your ~/.config/home-manager/home.nix (or a file imported by it)
{
  config,
  pkgs,
  ...
}:
# Home Manager modules usually get config and pkgs as arguments
let
  # Define the custom Steam launcher script within Home Manager's scope.
  # pkgs here refers to the pkgs available to your Home Manager environment.
  steamGamescopeWrapper = pkgs.writeScriptBin "steam-gamescope-launcher" ''
    #!/usr/bin/env bash
    set -xeuo pipefail

    gamescopeArgs=(
        --adaptive-sync
        --hdr-enabled
        --mangoapp
        --rt
        --steam
    )
    steamArgs=(
        -pipewire-dmabuf
        -tenfoot
    )
    mangoConfig=(
        cpu_temp
        gpu_temp
        ram
        vram
    )
    mangoVars=(
        MANGOHUD=1
        MANGOHUD_CONFIG="$(IFS=,; echo "$${mangoConfig[*]}")"
    )

    export PATH="${pkgs.gamescope}/bin:${pkgs.mangohud}/bin:$PATH"

    export "$${mangoVars[@]}"
    exec ${pkgs.gamescope}/bin/gamescope "$${gamescopeArgs[@]}" -- ${pkgs.steam}/bin/steam "$${steamArgs[@]}"
  '';
in {
  # You don't need 'programs.xdg.enable = true;' explicitly here in Home Manager;
  # xdg.desktopEntries will be available directly once Home Manager is active.

  # Home Manager usually manages user-level packages under `home.packages`.
  home.packages = with pkgs; [
    protonup-qt
    mangohud
    goverlay
    steamGamescopeWrapper # Add your wrapper script to your user's PATH
  ];

  # Define the desktop entry within Home Manager's xdg.desktopEntries
  xdg.desktopEntries.steam = {
    name = "Steam (Gamescope)";
    comment = "Launch Steam via Gamescope with MangoHud";
    exec = "${steamGamescopeWrapper}";
    icon = "steam";
    terminal = false;
    type = "Application";
    categories = ["Game" "Application"];
    startupNotify = true;
  };

  # If you previously had services.getty.autologinUser, that remains in configuration.nix.
  # Likewise for hardware.xone.enable and boot.kernelPackages.

  # Note: programs.steam.enable, programs.gamescope.enable, hardware.xone.enable
  # usually remain in configuration.nix (system-wide), as they install the programs
  # and drivers for the whole system.
}