feat(hosts): add lyrathorpe-console, a living-room games machine

New x86_64 host for a 4th-gen Core i7 (Haswell) with a GTX 1070 8 GB,
wired to a television and driven with a Bluetooth controller.

Session: greetd gets an initial_session, so the machine autologins into
the gamescope Steam session at boot with no greeter and no keyboard.
Quitting Steam falls back to greetd's default_session (ReGreet), where
the ordinary Sway session is available for keyboard-and-mouse work.

Graphics: the GTX 1070 is Pascal, so it needs driver branch 580
(nvidiaPackages.legacy_580) like the Mac Pro's Quadro P400 -- the
nixpkgs default (production, 595.x) dropped Pascal support.

Games: RetroArch built through retroarch-bare.wrapper with 17 cores
covering NES through PS2, GameCube and Wii; Clone Hero; and Steam with
Proton-GE and protontricks. RetroArch's menu toggle is bound to L3+R3,
without which there is no way to exit a running core on a machine with
no keyboard.

Proton prerequisites beyond what programs.steam already arranges: the
esync file-descriptor hard limit is raised from systemd's default
524288 to 1048576 (soft limit untouched), and Proton-GE is wired in via
extraCompatPackages. vm.max_map_count already defaults high enough in
nixpkgs and needs no override.

Content lives in a shared /srv/games tree created by systemd.tmpfiles,
laid out one directory per system under roms/ using the libretro/ES-DE
naming convention, plus bios/, saves/, states/, a Steam library folder
and Clone Hero's songs. RetroArch is pointed at it declaratively.

hardware-configuration.nix is a placeholder, not a hardware scan: the
machine is not installed yet. It assumes partition labels `nixos` and
`BOOT` and must be replaced with nixos-generate-config output.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

hosts/Console/gaming.nix

@@ -0,0 +1,247 @@
+# The games stack for the living-room machine: the Steam session that the TV
+# boots into, RetroArch with its cores, Clone Hero, and the controller plumbing.
+#
+# Session model. greetd (from ../../modules/sway.nix, which enables it for
+# ReGreet) gets an `initial_session`, so the machine autologins into the
+# gamescope Steam session at boot -- no keyboard, no greeter, straight to Big
+# Picture. Quitting Steam drops back to greetd's `default_session`, i.e. ReGreet,
+# where the ordinary Sway session can be picked for keyboard-and-mouse work.
+{ pkgs, ... }:
+
+let
+  # The account the television autologins as. Must match the user declared for
+  # this host in the flake host table.
+  tvUser = "lyrathorpe";
+
+  # Games library root. Deliberately outside any home directory: content is
+  # bulky, is the thing most likely to move to its own disk, and is shared
+  # between Steam, RetroArch and Clone Hero rather than owned by one of them.
+  # Mounting a second drive at this path is the only change that needs.
+  gamesRoot = "/srv/games";
+
+  # One ROM directory per emulated system. Names follow the libretro/ES-DE
+  # convention so a scraper or a second frontend recognises them without
+  # renaming anything.
+  romSystems = [
+    "nes"
+    "snes"
+    "gb"
+    "gbc"
+    "gba"
+    "n64"
+    "nds"
+    "gc"
+    "wii"
+    "mastersystem"
+    "gamegear"
+    "megadrive"
+    "sega32x"
+    "segacd"
+    "saturn"
+    "dreamcast"
+    "psx"
+    "ps2"
+    "psp"
+    "arcade"
+    "dos"
+  ];
+
+  # Everything under the root that is not a ROM directory. RetroArch is pointed
+  # at these below; Steam and Clone Hero have to be told about theirs in their
+  # own UIs (see docs/hosts/console.md).
+  libraryDirs = [
+    "bios" # RetroArch system directory: BIOS and firmware images
+    "saves" # in-game saves
+    "states" # save states
+    "playlists"
+    "screenshots"
+    "thumbnails"
+    "steam" # add as a Steam library folder from the client
+    "clonehero/songs"
+    "clonehero/backgrounds"
+  ];
+
+  # RetroArch and the cores this machine is expected to run. The wrapper already
+  # points RetroArch at the packaged assets, core info and joypad autoconfig
+  # profiles; `settings` here is merged on top of those.
+  retroarch = pkgs.retroarch-bare.wrapper {
+    cores = with pkgs.libretro; [
+      # Nintendo
+      nestopia # NES
+      snes9x # SNES
+      gambatte # Game Boy / Color
+      mgba # Game Boy Advance
+      mupen64plus # Nintendo 64
+      melonds # Nintendo DS
+      dolphin # GameCube / Wii
+      # Sega
+      genesis-plus-gx # Master System / Game Gear / Mega Drive
+      picodrive # 32X / Mega CD
+      beetle-saturn # Saturn
+      flycast # Dreamcast / NAOMI
+      # Sony
+      beetle-psx-hw # PlayStation, hardware renderer
+      pcsx2 # PlayStation 2 (LRPS2); needs a PS2 BIOS in RetroArch's system dir
+      ppsspp # PSP
+      # Arcade and PC
+      fbneo
+      mame2003-plus
+      dosbox-pure
+    ];
+    settings = {
+      # Applied on every launch via --appendconfig, so these three are fixed
+      # policy rather than saved preferences: changing them in the UI will not
+      # stick. Everything else stays user-editable as usual.
+      #
+      # Ozone is the controller-navigable menu; the TV has no keyboard.
+      menu_driver = "ozone";
+      video_fullscreen = "true";
+      # L3+R3 opens the RetroArch menu from inside a running core
+      # (INPUT_COMBO_L3_R3). Without a pad combo there is no way to exit a game
+      # without a keyboard, and no retro system this box emulates has L3/R3 on
+      # its own controller, so the binding cannot collide with a game.
+      input_menu_toggle_gamepad_combo = "2";
+
+      # Point RetroArch at the shared library instead of scattering content and
+      # state through ~/.config/retroarch. Key names are RetroArch's own; an
+      # unrecognised key in an appended config is ignored silently, so they are
+      # worth keeping in step with upstream.
+      system_directory = "${gamesRoot}/bios";
+      savefile_directory = "${gamesRoot}/saves";
+      savestate_directory = "${gamesRoot}/states";
+      playlist_directory = "${gamesRoot}/playlists";
+      screenshot_directory = "${gamesRoot}/screenshots";
+      thumbnails_directory = "${gamesRoot}/thumbnails";
+      # Where the content browser opens, so loading a game is a couple of
+      # D-pad presses rather than a walk up from the filesystem root.
+      rgui_browser_directory = "${gamesRoot}/roms";
+    };
+  };
+in
+{
+  programs.steam = {
+    enable = true;
+
+    # Registers the "Steam" wayland session (gamescope wrapping Steam in tenfoot
+    # mode) with the display manager and installs the steam-gamescope launcher.
+    gamescopeSession.enable = true;
+    gamescopeSession.env = {
+      # gamescope has to be pointed at NVIDIA's GBM implementation and GLX
+      # vendor explicitly; on the proprietary driver it otherwise fails to get a
+      # usable device and the session dies at startup.
+      GBM_BACKEND = "nvidia-drm";
+      __GLX_VENDOR_LIBRARY_NAME = "nvidia";
+    };
+
+    # Remote Play and local network game transfers are the point of a TV box on
+    # the same LAN as a desktop; both need their ports open.
+    remotePlay.openFirewall = true;
+    localNetworkGameTransfers.openFirewall = true;
+
+    # Proton-GE, selectable per title in Steam's compatibility settings. Covers
+    # the titles where Valve's Proton lags on codecs and anti-cheat shims. The
+    # module puts its steamcompattool output on STEAM_EXTRA_COMPAT_TOOLS_PATHS,
+    # which is what makes it appear in the client's Proton version list.
+    extraCompatPackages = [ pkgs.proton-ge-bin ];
+
+    # Winetricks against a Proton prefix: the standard repair tool when a title
+    # needs a runtime (dotnet, vcrun, Media Foundation) that Proton does not ship.
+    protontricks.enable = true;
+  };
+
+  # Proton prerequisites beyond what programs.steam already arranges.
+  #
+  # Already covered by the steam module, recorded here so it is not re-litigated:
+  # hardware.graphics 32-bit (the lib32 NVIDIA userspace Proton's 32-bit prefixes
+  # need), Steam's udev rules, 32-bit PipeWire, and the system fonts Wine renders
+  # with (Liberation and DejaVu arrive with fonts.enableDefaultPackages).
+  # vm.max_map_count is 1048576 in the nixpkgs default sysctls, which is above
+  # what DX12/Unreal titles need -- no override required.
+  #
+  # What is not covered: esync opens one eventfd per Wine sync object and runs
+  # out against systemd's default 524288 hard limit in the heaviest titles.
+  # Raise the hard limit only; the soft limit stays at the default, because
+  # lifting that breaks select()-based programs elsewhere on the system.
+  systemd.settings.Manager.DefaultLimitNOFILE = "1024:1048576";
+
+  # capSysNice lets gamescope raise its own scheduling priority, which is what
+  # keeps the compositor smooth while a game saturates the GPU. It installs
+  # gamescope as a setcap wrapper instead of a plain systemPackages entry;
+  # /run/wrappers/bin precedes the system profile on PATH, so steam-gamescope
+  # still resolves it.
+  programs.gamescope = {
+    enable = true;
+    capSysNice = true;
+  };
+
+  # Applies the performance CPU governor (and drops it again) around games that
+  # ask for it; Steam's Proton builds and most native titles do.
+  programs.gamemode.enable = true;
+
+  # Autologin into the Steam session. The launcher is not exposed as a package
+  # by the steam module -- it is built inside it and added to
+  # environment.systemPackages -- so reference it through the system profile.
+  # greetd's `restart` option defaults to false once initial_session is set,
+  # which is what stops a logout from looping straight back into autologin.
+  services.greetd.settings.initial_session = {
+    command = "/run/current-system/sw/bin/steam-gamescope";
+    user = tvUser;
+  };
+
+  # Controllers.
+  #
+  # Xbox One/Series pads over Bluetooth need xpadneo: the in-kernel xpad driver
+  # does not handle them well over BT (wrong button mapping, no rumble). The
+  # module turns on bluez itself; powerOnBoot is set below so the adapter is up
+  # before the Steam session starts and a pad can reconnect unattended.
+  #
+  # Everything else is in-kernel and needs no configuration: wired Xbox 360 pads
+  # (and the 360 wireless receiver) via xpad, DualSense/DualShock 4 via
+  # hid-playstation over USB and Bluetooth, and Clone Hero guitars as plain USB
+  # HID gamepads. xpadneo does not contend with xpad -- it binds Bluetooth HID
+  # devices, and the 360 pad is not HID-compliant. hardware.xone is deliberately
+  # left off: it blacklists xpad, which would break the 360 pads.
+  #
+  # hidraw access for the PlayStation pads (LED, battery, dualsensectl) comes
+  # from Steam's udev rules, which programs.steam enables via
+  # hardware.steam-hardware.
+  hardware.xpadneo.enable = true;
+  hardware.bluetooth = {
+    enable = true;
+    powerOnBoot = true;
+    # Battery level reporting for Bluetooth gamepads is still behind bluez's
+    # experimental flag.
+    settings.General.Experimental = true;
+  };
+
+  # The games library, created at boot so the directories exist before anything
+  # tries to write into them. Mode 2775 is setgid: the owning group is carried
+  # onto anything created inside, so a second account (or an rsync from another
+  # machine) does not end up with files the TV user cannot write. Directories
+  # are created if missing and otherwise left alone -- nothing here removes or
+  # rewrites content.
+  systemd.tmpfiles.rules =
+    let
+      dir = path: "d ${path} 2775 ${tvUser} users -";
+    in
+    [
+      (dir gamesRoot)
+      (dir "${gamesRoot}/roms")
+    ]
+    ++ map (system: dir "${gamesRoot}/roms/${system}") romSystems
+    ++ map (sub: dir "${gamesRoot}/${sub}") libraryDirs;
+
+  # 32-bit ALSA for the older native titles that talk to ALSA directly rather
+  # than through the PulseAudio shim; programs.steam derives
+  # pipewire.alsa.support32Bit from this. PipeWire itself and the Pulse shim
+  # come from ../../modules/workstation.nix.
+  services.pipewire.alsa.enable = true;
+
+  environment.systemPackages = [
+    retroarch
+    pkgs.clonehero
+    pkgs.dualsensectl # DualSense LED/battery/mic control from the shell
+    pkgs.mangohud # FPS/frametime overlay; use `mangohud %command%` in Steam
+    pkgs.vulkan-tools # vulkaninfo, for checking the 32/64-bit ICDs Proton needs
+  ];
+}