nixos/hosts/yarn/default.nix

{
  pkgs,
  lib,
  username,
  inputs,
  site_config,
  ...
}:
{
  imports = [
    ../../modules/desktop-common.nix
    ../../modules/desktop-jovian.nix
    ../../modules/no-rgb.nix
    ./disk.nix
    ./impermanence.nix
    ./lact.nix
    ./vr.nix
    ./forza-trigger
    ../../modules/desktop-game-mods.nix

    inputs.impermanence.nixosModules.impermanence
  ];

  fileSystems."/media/games" = {
    device = "/dev/disk/by-uuid/1878136e-765d-4784-b204-3536ab4fdac8";
    fsType = "f2fs";
    options = [ "nofail" ];
  };

  systemd.targets = {
    sleep.enable = false;
    suspend.enable = false;
    hibernate.enable = false;
    hybrid-sleep.enable = false;
  };

  networking.hostId = "abf570f9";

  # Static IP for consistent SSH access
  networking.networkmanager.ensureProfiles.profiles.enp7s0-static = {
    connection = {
      id = "enp7s0-static";
      type = "ethernet";
      interface-name = "enp7s0";
      autoconnect = true;
    };
    ipv4 = {
      method = "manual";
      address1 = "${site_config.hosts.yarn.ip}/24,${site_config.lan.gateway}";
      dns = lib.concatMapStrings (n: "${n};") site_config.dns_servers;
    };
    ipv6.method = "disabled";
  };

  services.openssh = {
    enable = true;
    ports = [ 22 ];
    settings = {
      PasswordAuthentication = false;
      PermitRootLogin = "yes";
    };
  };

  users.users.${username}.openssh.authorizedKeys.keys = [
    site_config.ssh_keys.laptop
  ];

  users.users.root.openssh.authorizedKeys.keys = [
    site_config.ssh_keys.laptop
    site_config.ssh_keys.ci_deploy
  ];

  programs.steam = {
    remotePlay.openFirewall = true;
    localNetworkGameTransfers.openFirewall = true;
  };

  environment.systemPackages = [ pkgs.jovian-stubs ];

  # yarn is not a Steam Deck
  jovian.devices.steamdeck.enable = false;

  # PS5 DualSense adaptive triggers in Forza Horizon 4 / 5.
  services.forzaTrigger.enable = true;

  # Declarative game-file mods on top of Steam (file drops only; Steam launch
  # options live in `programs.steam.config.apps` below).
  #
  # fh5-no-intro: stub the 40 MB T10/Microsoft Studios cold-start splash.
  #   Two copies live in the install (SD + hires); engine picks one based on
  #   the installed asset profile, so stub both. PCGamingWiki documents both
  #   paths under "Skip intro video".
  #
  # fh5-optiscaler: drop OptiScaler v0.9.1 + a hand-written FH5/RDNA3 INI into
  #   the install dir to enable FSR 4 INT8 on this Navi 32 box. OptiScaler
  #   intercepts FH5's DLSS/XeSS calls and reroutes them through the bundled
  #   FFX SDK. Override values + sources live in
  #   ./optiscaler-fh5-rdna3.ini; keys not listed there fall through to
  #   OptiScaler's "auto" defaults.
  #
  #   Required one-time per-game setup the user has to do in Steam (the
  #   in-game upscaler picker has no public API):
  #     - In-game: switch the Upscaling option from FSR 2.2 to DLSS or XeSS
  #       (FSR 2 inputs aren't intercepted). Press Insert to open the Opti
  #       overlay and set the FFX upscaler to FSR 4.
  #
  #   Caveats:
  #   - OptiScaler.ini is dropped with mode = "init" so in-game overlay edits
  #     persist. The hand-written template is only written on first apply (or
  #     after manual deletion). To push a new default into an existing
  #     install: rm OptiScaler.ini in the FH5 dir, then `systemctl start
  #     game-mods`. The DLLs and other static assets stay mode = "create" so
  #     they're updated on every OptiScaler version bump.
  #   - OptiScaler's installation page warns against use with online games.
  #     FH5 has no kernel-mode anti-cheat but Playground does server-side
  #     telemetry. Use at your own risk.
  services.gameMods =
    let
      optiPkg = pkgs.optiscaler;
      fromOpti = relpath: {
        source = "${optiPkg}/${relpath}";
        mode = "create";
      };
    in
    {
      enable = true;
      mods."fh5-no-intro" = {
        steamAppId = 1551360;
        files."media/UI/Videos/T10_MS_Combined.bk2".empty = true;
        files."media/UI/Videos/hires/T10_MS_Combined.bk2".empty = true;
      };
      mods."fh5-optiscaler" = {
        steamAppId = 1551360;
        files = {
          # OptiScaler.dll is renamed to dxgi.dll so FH5's DLL search order
          # picks it up as the dxgi shim per the OptiScaler FH5 wiki page.
          "dxgi.dll" = fromOpti "OptiScaler.dll";
          "OptiScaler.ini" = {
            source = ./optiscaler-fh5-rdna3.ini;
            # init: drop the template once, then leave it alone so the in-game
            # overlay can persist user tweaks.
            mode = "init";
          };
        }
        // lib.genAttrs [
          "D3D12_Optiscaler/D3D12Core.dll"
          "amd_fidelityfx_dx12.dll"
          "amd_fidelityfx_framegeneration_dx12.dll"
          "amd_fidelityfx_upscaler_dx12.dll"
          "amd_fidelityfx_vk.dll"
          "dlssg_to_fsr3_amd_is_better.dll"
          "fakenvapi.dll"
          "fakenvapi.ini"
          "libxell.dll"
          "libxess.dll"
          "libxess_dx11.dll"
          "libxess_fg.dll"
        ] fromOpti;
      };
    };

  # Steam launch options + per-app compat-tool pin via steam-config-nix
  # (different-name/steam-config-nix). The patcher runs as a system oneshot
  # at activation; closeSteam = true ensures Steam is shut down before the
  # localconfig.vdf write so Steam can't clobber it on its next exit.
  programs.steam.config = {
    enable = true;
    closeSteam = true;
    defaultCompatTool = "GE-Proton";
    apps."fh5" = {
      id = 1551360;
      compatTool = "GE-Proton";
      launchOptions.env = {
        # OptiScaler FSR 4 INT8 path on this RDNA 3 (Navi 32) box.
        # PROTON_FSR4_UPGRADE opts FH5 into Proton's FSR 4 DLL upgrade;
        # DXIL_SPIRV_CONFIG fixes the broken visuals the wmma RDNA3 emulation
        # path otherwise produces. Source: OptiScaler FSR4 wiki Linux Setup.
        PROTON_FSR4_UPGRADE = "1";
        DXIL_SPIRV_CONFIG = "wmma_rdna3_workaround";
        # vkd3d-proton stutter/crash workaround on this box; remove when a
        # future Proton release fixes the upload-hvv path upstream.
        VKD3D_CONFIG = "no_upload_hvv";
      };
    };
  };
}