game-mods: drop in-house launchOptions writer, hardcode FH5 ini

Replaces three handfuls of custom code with upstream / static data:

- Per-app Steam launch options now declared via different-name/steam-
  config-nix's `programs.steam.config.apps.<n>` instead of a custom
  ~70-line `apply_launch_options` Python function. The dropped writer
  was racy: it edited localconfig.vdf without checking for a running
  Steam, so any timer firing while Steam was open would lose its
  changes on the next Steam shutdown. steam-config-nix's `closeSteam`
  flag closes that race.

  Also moves the GE-Proton compat-tool pin to declarative config —
  one fewer manual click in Steam UI to remember.

- `mods.<>.launchOptions` option, the `launchOptionsData` aggregation,
  and `LAUNCH_OPTIONS_DATA` are removed from desktop-game-mods.nix.
  The module now does file-drops only; Steam config lives in its own
  `programs.steam.config` namespace, where it belongs.

  fh5-vkd3d-no-hvv (which existed only to set VKD3D_CONFIG) collapses
  into the FH5 launchOptions block in hosts/yarn/default.nix.

- `unitConfig.X-ConfigHash` on game-mods.service is replaced with
  `restartTriggers`. NixOS already emits `X-Restart-Triggers=<hash>`
  on the unit; the workaround was redundant. The Type=oneshot,
  RemainAfterExit=no semantics make `systemctl restart` re-run
  ExecStart cleanly on hash change.

- The awk pipeline that patched OptiScaler's stock OptiScaler.ini at
  build time is replaced with a hand-written hosts/yarn/optiscaler-
  fh5-rdna3.ini containing only the keys we override (5 of them).
  OptiScaler's Config::readString defaults missing keys to "auto"
  (Config.cpp:1568), so a minimal file is sufficient. Side benefits:
  one upstream-source dependency removed, a key-rename in upstream
  becomes a behavior change rather than a silent awk-no-match.

  Override values + sources:
    Fsr4Update=true              FH5 wiki, FSR4 Linux Setup
    DlssReactiveMaskBias=0.65    FH5 wiki, "Known Issues"
    FsrNonLinearColorSpace=true  FSR4 wiki, "Image Quality"
    EnableFsr2Inputs=false       FH5 wiki, "Known Issues"
    Dxgi=false                   FH5 wiki

- forza-trigger's three custom Python derivations (pydualsense,
  hidapi-usb, fdp) factored out of default.nix into a sibling
  python-packages.nix. Same logic, single-purpose file. Bumping a
  version is now a one-place hash roll.

- pkgs.dualsensectl removed from the daemon's environment.system-
  Packages. Single-shot writes from the CLI get clobbered by the BG
  sendReport thread within ~4ms anyway, so the tool is only useful
  with the daemon stopped — not worth the unconditional install.
  Bring it in ad-hoc with `nix-shell -p dualsensectl`.

flake.lock

@@ -416,6 +416,27 @@
         "type": "github"
       }
     },
+    "flake-parts_4": {
+      "inputs": {
+        "nixpkgs-lib": [
+          "steam-config-nix",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1765835352,
+        "narHash": "sha256-XswHlK/Qtjasvhd1nOa1e8MgZ8GS//jBoTqWtrS1Giw=",
+        "owner": "hercules-ci",
+        "repo": "flake-parts",
+        "rev": "a34fae9c08a15ad73f295041fec82323541400a9",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "repo": "flake-parts",
+        "type": "github"
+      }
+    },
     "flake-utils": {
       "inputs": {
         "systems": "systems_2"
@@ -454,7 +475,7 @@
     },
     "flake-utils_3": {
       "inputs": {
-        "systems": "systems_10"
+        "systems": "systems_11"
       },
       "locked": {
         "lastModified": 1731533236,
@@ -1103,6 +1124,7 @@
         "rust-overlay": "rust-overlay",
         "senior_project-website": "senior_project-website",
         "srvos": "srvos",
+        "steam-config-nix": "steam-config-nix",
         "trackerlist": "trackerlist",
         "vpn-confinement": "vpn-confinement",
         "website": "website",
@@ -1204,6 +1226,28 @@
         "type": "github"
       }
     },
+    "steam-config-nix": {
+      "inputs": {
+        "flake-parts": "flake-parts_4",
+        "nixpkgs": [
+          "nixpkgs"
+        ],
+        "systems": "systems_10"
+      },
+      "locked": {
+        "lastModified": 1773421780,
+        "narHash": "sha256-bkZGvIWV8JavLMQ2KzddrMCf9YBeiIM4OgdiwKcFx8M=",
+        "owner": "different-name",
+        "repo": "steam-config-nix",
+        "rev": "7b8021b2739733c547e2fe02739e6b8452813aa7",
+        "type": "github"
+      },
+      "original": {
+        "owner": "different-name",
+        "repo": "steam-config-nix",
+        "type": "github"
+      }
+    },
     "systems": {
       "locked": {
         "lastModified": 1681028828,
@@ -1234,6 +1278,21 @@
         "type": "github"
       }
     },
+    "systems_11": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    },
     "systems_2": {
       "locked": {
         "lastModified": 1681028828,

flake.nix

@@ -82,6 +82,10 @@
       url = "github:ChrisOboe/json2steamshortcut";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+    steam-config-nix = {
+      url = "github:different-name/steam-config-nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
     # Google's official agent-skills for Android development (Apache 2.0).
     # Consumed by home/progs/pi.nix and exposed under ~/.omp/agent/skills/.
     android-skills = {
@@ -238,6 +242,7 @@
               }
             )
             { nixpkgs.overlays = [ (import ./lib/overlays.nix) ]; }
+            inputs.steam-config-nix.nixosModules.default
             ./hosts/${hostname}/default.nix
           ];
         };

hosts/yarn/default.nix

@@ -83,61 +83,40 @@
   # PS5 DualSense adaptive triggers in Forza Horizon 4 / 5.
   services.forzaTrigger.enable = true;
 
-  # Declarative game-file mods on top of Steam.
+  # 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 FH5-tuned OptiScaler.ini into
+  # fh5-optiscaler: drop OptiScaler v0.9.1 + a hand-written FH5/RDNA3 INI into
-  #   the install dir to enable FSR 4 INT8 on this RDNA 3 Navi 32 box.
+  #   the install dir to enable FSR 4 INT8 on this Navi 32 box. OptiScaler
-  #   OptiScaler intercepts FH5's DLSS/XeSS calls and reroutes them through
+  #   intercepts FH5's DLSS/XeSS calls and reroutes them through the bundled
-  #   the bundled FFX SDK. Settings flipped from upstream defaults:
+  #   FFX SDK. Override values + sources live in
-  #     Fsr4Update         auto -> true   # FSR 4 path required for INT8 RDNA 3
+  #   ./optiscaler-fh5-rdna3.ini; keys not listed there fall through to
-  #     Dxgi               auto -> false  # FH5 wiki: required for 0.9
+  #   OptiScaler's "auto" defaults.
-  #     DlssReactiveMaskBias auto -> 0.65 # FH5 wiki: fixes flickering lights, reduces car ghosting
   #
-  #   Required one-time per-game setup in Steam (Proton picker is not
+  #   Required one-time per-game setup the user has to do in Steam (the
-  #   declarable from NixOS; launch options are written declaratively below):
+  #   in-game upscaler picker has no public API):
-  #     1. Properties -> Compatibility: force "GE-Proton" (proton-ge-bin is
+  #     - In-game: switch the Upscaling option from FSR 2.2 to DLSS or XeSS
-  #        already in extraCompatPackages; pick the latest installed).
-  #        Steam must be closed when the launch options write happens, or
-  #        Steam will overwrite our localconfig.vdf edit on shutdown.
-  #     2. 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 awk-patched template below is only written on first apply
+  #     persist. The hand-written template is only written on first apply (or
-  #     (or after manual deletion). To push a new default into an existing
+  #     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.
-  #
-  # fh5-vkd3d-no-hvv: append `VKD3D_CONFIG=no_upload_hvv` to FH5's launch
-  #   options. Disables vkd3d-proton's host-visible VRAM upload heap, which
-  #   works around a Proton stutter/crash on this box. Kept as its own mod
-  #   (no files, just env) so the workaround can be removed independently of
-  #   OptiScaler when a future Proton release fixes the underlying issue.
   services.gameMods =
     let
       optiPkg = pkgs.optiscaler;
-      # OptiScaler.ini ships with CRLF line endings, so we use awk with explicit
-      # RS/ORS to keep the rewrites line-ending agnostic. The regex is matched
-      # against the CR-stripped record, the original CRLF is restored on output.
-      optiIni = pkgs.runCommand "OptiScaler-fh5.ini" { } ''
-        awk -v RS='\r\n' -v ORS='\r\n' '
-          /^Fsr4Update=auto$/           { print "Fsr4Update=true"; next }
-          /^Dxgi=auto$/                 { print "Dxgi=false"; next }
-          /^DlssReactiveMaskBias=auto$/ { print "DlssReactiveMaskBias=0.65"; next }
-          { print }
-        ' ${optiPkg}/OptiScaler.ini > $out
-      '';
       fromOpti = relpath: {
         source = "${optiPkg}/${relpath}";
         mode = "create";
@@ -152,24 +131,14 @@
       };
       mods."fh5-optiscaler" = {
         steamAppId = 1551360;
-        # RDNA 3 (Navi 32) FSR 4 path on Linux:
-        #   PROTON_FSR4_UPGRADE=1            opts FH5 into Proton's FSR 4 upgrade.
-        #   DXIL_SPIRV_CONFIG=wmma_rdna3_... fixes broken visuals on RDNA 3 per
-        #                                    the OptiScaler FSR4 wiki.
-        # Other FH5-targeting mods (e.g. fh5-vkd3d-no-hvv) append their own
-        # entries to this list; the module joins them and adds %command%.
-        launchOptions = [
-          "PROTON_FSR4_UPGRADE=1"
-          "DXIL_SPIRV_CONFIG=wmma_rdna3_workaround"
-        ];
         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 = optiIni;
+            source = ./optiscaler-fh5-rdna3.ini;
-            # init: drop the patched template once, then leave it alone so
+            # init: drop the template once, then leave it alone so the in-game
-            # the in-game overlay can persist user tweaks.
+            # overlay can persist user tweaks.
             mode = "init";
           };
         }
@@ -188,9 +157,30 @@
           "libxess_fg.dll"
         ] fromOpti;
       };
-      mods."fh5-vkd3d-no-hvv" = {
+    };
-        steamAppId = 1551360;
+
-        launchOptions = [ "VKD3D_CONFIG=no_upload_hvv" ];
+  # 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";
+      };
     };
   };
 }

hosts/yarn/forza-trigger/default.nix

@@ -17,7 +17,7 @@
 #     controller (Settings → Controller → "PlayStation Configuration Support":
 #     OFF). Bluetooth works too but the udev/hidraw path is more reliable
 #     over USB.
-#   - in Forza, HUD options \u2192 set Data Out: ON, Data Out IP: 127.0.0.1,
+#   - in Forza, HUD options → set Data Out: ON, Data Out IP: 127.0.0.1,
 #     Data Out IP Port: 5300, and (FM7 only) Data Out Packet Format: CAR DASH.
 #
 # System-interaction notes:
@@ -26,102 +26,17 @@
 #     in pydualsense's source). Forza Horizon is single-player so this is
 #     usually fine. If you need to pin a specific controller, the cleanest
 #     route is monkey-patching `pydualsense.__find_device`.
-#   - The included `dualsensectl` will be overwritten by our BG thread within
+#   - `pkgs.dualsensectl` is intentionally NOT installed by default
-#     ~4 ms; use `systemctl --user stop forza-trigger` first when debugging.
+#     (single-shot writes from it get overwritten by our BG thread within
+#     ~4 ms). Bring it in ad-hoc with `nix-shell -p dualsensectl` and stop
+#     this service first via `systemctl --user stop forza-trigger`.
 #   - Hot-plug recovery happens in-process: the daemon polls pydualsense's BG
 #     thread liveness and re-runs `pydualsense.init()` on disconnect. systemd's
 #     `Restart=on-failure` exists only as a crash-recovery safety net.
 let
   cfg = config.services.forzaTrigger;
-  python = pkgs.python3;
+  pythonPackages = import ./python-packages.nix { inherit lib pkgs; };
-
+  inherit (pythonPackages) pydualsense fdp;
-  # CFFI bindings to libhidapi. Upstream is flok/hidapi-cffi published on
-  # PyPI under the name `hidapi-usb`. The shipped hidapi.py picks a libhidapi
-  # soname via ffi.dlopen() — we substitute absolute store paths so the
-  # interpreter inside our wrapped python env can find it without
-  # LD_LIBRARY_PATH gymnastics.
-  hidapi-usb = python.pkgs.buildPythonPackage rec {
-    pname = "hidapi-usb";
-    version = "0.3.2";
-    format = "setuptools";
-
-    # PyPI's project URL slug uses a hyphen (`hidapi-usb`) but the sdist file
-    # itself is PEP-625-normalized to an underscore (`hidapi_usb-…`). Stock
-    # fetchPypi assumes they match — they don't here, so fetch by direct URL.
-    src = pkgs.fetchurl {
-      url = "https://files.pythonhosted.org/packages/55/80/960ae94b615e26a7d1aeebe8e9fefda2f25608bf1016f9aec268b328c35e/hidapi_usb-${version}.tar.gz";
-      hash = "sha256-oxp+2i+qqYd1uwiS2Dh8/PzO62iYQQXpR936MnDIFk0=";
-    };
-
-    propagatedBuildInputs = [ python.pkgs.cffi ];
-
-    postPatch = ''
-      substituteInPlace hidapi.py \
-        --replace-fail "'libhidapi-hidraw.so'," "'${pkgs.hidapi}/lib/libhidapi-hidraw.so'," \
-        --replace-fail "'libhidapi-hidraw.so.0'," "'${pkgs.hidapi}/lib/libhidapi-hidraw.so.0',"
-    '';
-
-    pythonImportsCheck = [ "hidapi" ];
-
-    meta = {
-      description = "CFFI wrapper for hidapi (used by pydualsense)";
-      homepage = "https://github.com/flok/hidapi-cffi";
-      license = lib.licenses.bsd3;
-    };
-  };
-
-  pydualsense = python.pkgs.buildPythonPackage rec {
-    pname = "pydualsense";
-    version = "0.7.5";
-    format = "pyproject";
-
-    src = python.pkgs.fetchPypi {
-      pname = "pydualsense";
-      inherit version;
-      hash = "sha256-YgX8AJE4f8p7geKT3xlCD0Mlh1GcyHpBz4rEIqdwKgs=";
-    };
-
-    nativeBuildInputs = [ python.pkgs.poetry-core ];
-    propagatedBuildInputs = [ hidapi-usb ];
-
-    pythonImportsCheck = [ "pydualsense" ];
-
-    meta = {
-      description = "Control your PS5 DualSense controller from Python";
-      homepage = "https://github.com/flok/pydualsense";
-      license = lib.licenses.mit;
-    };
-  };
-
-  # Single-file Forza UDP packet parser. Pinned to a known-good commit; the
-  # repo is dormant (last commit 2021) but the FH4 packet layout is frozen
-  # and FH5 reuses it byte-for-byte.
-  fdp = python.pkgs.buildPythonPackage {
-    pname = "fdp";
-    version = "0-unstable-2021-05-28";
-    format = "other";
-
-    src = pkgs.fetchurl {
-      url = "https://raw.githubusercontent.com/nettrom/forza_motorsport/61845cb7ff4082211292a51ce3c49edbfd2d6503/fdp.py";
-      hash = "sha256-osFaVF9VaEzU4dp3x6KN6OF7SXsd9ZBwvilU+xTT7mM=";
-    };
-
-    dontUnpack = true;
-
-    installPhase = ''
-      runHook preInstall
-      install -Dm644 $src $out/${python.sitePackages}/fdp.py
-      runHook postInstall
-    '';
-
-    pythonImportsCheck = [ "fdp" ];
-
-    meta = {
-      description = "ForzaDataPacket — Forza Motorsport / Horizon UDP packet parser";
-      homepage = "https://github.com/nettrom/forza_motorsport";
-      license = lib.licenses.mit;
-    };
-  };
 
   forzaTrigger = pkgs.writers.writePython3Bin "forza-trigger" {
     libraries = [
@@ -173,12 +88,7 @@ in
       KERNEL=="hidraw*", KERNELS=="*054C:0DF2*", MODE="0660", TAG+="uaccess"
     '';
 
-    environment.systemPackages = [
+    environment.systemPackages = [ forzaTrigger ];
-      forzaTrigger
-      # CLI companion for sanity-checking the controller (battery, lightbar,
-      # raw trigger modes, monitor add/remove events).
-      pkgs.dualsensectl
-    ];
 
     # User-level service so it inherits the seat-bound uaccess ACL on
     # /dev/hidraw* and dies cleanly when the user logs out.

hosts/yarn/forza-trigger/python-packages.nix

@@ -0,0 +1,107 @@
+# Python packages forza_trigger.py imports that aren't in nixpkgs. Returns
+# an attrset consumed by ./default.nix.
+#
+# Bumping a version: change `version` and `hash`, then `nix build` — Nix
+# fails with the new sha256 in the error message, paste it back in.
+{
+  lib,
+  pkgs,
+  python ? pkgs.python3,
+}:
+let
+  py = python.pkgs;
+in
+rec {
+  # CFFI bindings to libhidapi (flok/hidapi-cffi on PyPI). pydualsense's
+  # `import hidapi` resolves to this — nixpkgs' python3Packages.hidapi is the
+  # Cython wrapper from trezor/cython-hidapi which exposes a different
+  # `import hid` API and can't satisfy pydualsense.
+  hidapi-usb = py.buildPythonPackage rec {
+    pname = "hidapi-usb";
+    version = "0.3.2";
+    format = "setuptools";
+
+    # PyPI's project URL slug uses a hyphen (`hidapi-usb`) but the sdist file
+    # itself is PEP-625-normalized to an underscore (`hidapi_usb-…`). Stock
+    # fetchPypi assumes they match — they don't here, so fetch by direct URL.
+    src = pkgs.fetchurl {
+      url = "https://files.pythonhosted.org/packages/55/80/960ae94b615e26a7d1aeebe8e9fefda2f25608bf1016f9aec268b328c35e/hidapi_usb-${version}.tar.gz";
+      hash = "sha256-oxp+2i+qqYd1uwiS2Dh8/PzO62iYQQXpR936MnDIFk0=";
+    };
+
+    propagatedBuildInputs = [ py.cffi ];
+
+    # Upstream's hidapi.py walks a tuple of soname strings via ffi.dlopen()
+    # until one resolves. Pin the two Linux hidraw entries to absolute store
+    # paths so the wrapped Python in our writePython3Bin closure finds them
+    # without LD_LIBRARY_PATH wrapping. The libusb / iohidmanager / dylib /
+    # dll entries are dead code on Linux. --replace-fail makes a rename in
+    # upstream's tuple a loud build error rather than a silent ImportError
+    # at runtime.
+    postPatch = ''
+      substituteInPlace hidapi.py \
+        --replace-fail "'libhidapi-hidraw.so'," "'${pkgs.hidapi}/lib/libhidapi-hidraw.so'," \
+        --replace-fail "'libhidapi-hidraw.so.0'," "'${pkgs.hidapi}/lib/libhidapi-hidraw.so.0',"
+    '';
+
+    pythonImportsCheck = [ "hidapi" ];
+
+    meta = {
+      description = "CFFI wrapper for hidapi (used by pydualsense)";
+      homepage = "https://github.com/flok/hidapi-cffi";
+      license = lib.licenses.bsd3;
+    };
+  };
+
+  pydualsense = py.buildPythonPackage rec {
+    pname = "pydualsense";
+    version = "0.7.5";
+    format = "pyproject";
+
+    src = py.fetchPypi {
+      inherit pname version;
+      hash = "sha256-YgX8AJE4f8p7geKT3xlCD0Mlh1GcyHpBz4rEIqdwKgs=";
+    };
+
+    nativeBuildInputs = [ py.poetry-core ];
+    propagatedBuildInputs = [ hidapi-usb ];
+
+    pythonImportsCheck = [ "pydualsense" ];
+
+    meta = {
+      description = "Control your PS5 DualSense controller from Python";
+      homepage = "https://github.com/flok/pydualsense";
+      license = lib.licenses.mit;
+    };
+  };
+
+  # Single-file Forza UDP packet parser (nettrom/forza_motorsport). Pinned to
+  # a known-good commit; the repo is dormant (last commit 2021) but the FH4
+  # packet layout is frozen and FH5 reuses it byte-for-byte.
+  fdp = py.buildPythonPackage {
+    pname = "fdp";
+    version = "0-unstable-2021-05-28";
+    format = "other";
+
+    src = pkgs.fetchurl {
+      url = "https://raw.githubusercontent.com/nettrom/forza_motorsport/61845cb7ff4082211292a51ce3c49edbfd2d6503/fdp.py";
+      hash = "sha256-osFaVF9VaEzU4dp3x6KN6OF7SXsd9ZBwvilU+xTT7mM=";
+    };
+
+    dontUnpack = true;
+
+    installPhase = ''
+      runHook preInstall
+      install -Dm644 $src $out/${python.sitePackages}/fdp.py
+      runHook postInstall
+    '';
+
+    pythonImportsCheck = [ "fdp" ];
+
+    meta = {
+      description = "ForzaDataPacket — Forza Motorsport / Horizon UDP packet parser";
+      homepage = "https://github.com/nettrom/forza_motorsport";
+      license = lib.licenses.mit;
+    };
+  };
+}

hosts/yarn/optiscaler-fh5-rdna3.ini

@@ -0,0 +1,39 @@
+; OptiScaler.ini overrides for Forza Horizon 5 on RDNA 3 (Navi 32) under
+; Linux/Proton with FSR 4 INT8 enabled. Tested on OptiScaler 0.9.1.
+;
+; Keys not listed here fall through to OptiScaler's "auto" defaults
+; (Config.cpp: missing keys silently resolve to std::nullopt -> _defaultValue).
+;
+; Sources:
+;   - https://github.com/optiscaler/OptiScaler/wiki/Forza-Horizon-5
+;   - https://github.com/optiscaler/OptiScaler/wiki/FSR4-Compatibility-List
+;
+; Companion launch-option env vars (set via programs.steam.config in
+; hosts/yarn/default.nix):
+;   PROTON_FSR4_UPGRADE=1
+;   DXIL_SPIRV_CONFIG=wmma_rdna3_workaround   (RDNA 3 INT8 visuals fix)
+;   VKD3D_CONFIG=no_upload_hvv                (vkd3d-proton stutter workaround)
+
+[Inputs]
+; FSR2 inputs are buggy in FH5; OptiScaler 0.7.8+ auto-disables them per game
+; but explicit is safer across version bumps. Source: FH5 wiki ("Known Issues").
+EnableFsr2Inputs=false
+
+[FSR]
+; DirectX 12 Agility SDK upgrade. Required for the FSR 4 path on RDNA 3 INT8
+; under Proton (the FFX SDK shipped with the game predates FSR 4). Source:
+; FSR4 Compatibility wiki, "Linux Setup" section.
+Fsr4Update=true
+
+; FH5 wiki: 0.65 fixes flickering lights and reduces car ghosting with FSR-FG.
+DlssReactiveMaskBias=0.65
+
+; FSR 4 on RDNA 3 IQ recommendation; mitigates white flashes and artifacting
+; from the INT8 emulation path. Source: FSR4 Compatibility wiki, "Image Quality".
+FsrNonLinearColorSpace=true
+
+[Spoofing]
+; FH5 wiki recommendation. The auto default on AMD spoofs to NVIDIA, which
+; OptiScaler 0.9 deliberately drops for FH5; pinning false here makes the
+; behavior version-proof.
+Dxgi=false

modules/desktop-game-mods.nix

@@ -21,11 +21,9 @@
 #   location  = "install" (default, steamapps/common/<dir>) | "prefix"
 #                (steamapps/compatdata/<appid>/pfx — for user-storage mods)
 #
-# Each mod can also declare `launchOptions = [ "FOO=bar" ]`. Lists from
+# Per-app Steam launch options live in `programs.steam.config.apps.<name>`
-# every mod targeting the same Steam App ID are concatenated (mod-name
+# from the steam-config-nix flake — declare them there alongside `compatTool`
-# alphabetical), joined with spaces, and `%command%` is appended once.
+# and other Steam config that this module deliberately does not touch.
-# The result is written into Steam's per-app block in localconfig.vdf
-# so it persists across Steam restarts.
 #
 # Example: stub the cold-start intro video, plus drop a sound mod XML into
 # the Wine prefix's user storage.
@@ -110,27 +108,6 @@ let
         default = { };
         description = "Files to modify, keyed by path relative to game root.";
       };
-      launchOptions = mkOption {
-        type = types.listOf types.str;
-        default = [ ];
-        example = [
-          "PROTON_FSR4_UPGRADE=1"
-          "DXIL_SPIRV_CONFIG=wmma_rdna3_workaround"
-        ];
-        description = ''
-          Components to prepend to Steam's per-app LaunchOptions string.
-          Every mod that targets the same steamAppId contributes; the lists
-          are concatenated (in mod-name alphabetical order, preserving each
-          mod's internal order), joined with single spaces, and the literal
-          `%command%` is appended once at the end. List entries must not
-          contain `%command%` themselves.
-
-          An empty list (default) leaves Steam's existing LaunchOptions value
-          untouched, so Steam-UI edits and other games' launch options are
-          unaffected. Typical entries are env-var assignments
-          (`PROTON_FSR4_UPGRADE=1`) or wrappers (`gamemoderun`).
-        '';
-      };
     };
   };
 
@@ -162,28 +139,6 @@ let
     in
     builtins.toJSON entries;
 
-  # Launch-options data as JSON. Mods are grouped by steamAppId, their
-  # launchOptions lists are concatenated (mod-name alphabetical order from
-  # mapAttrsToList), joined with spaces, and `%command%` is appended once.
-  # AppIds whose total contribution is empty are omitted entirely so the
-  # apply script leaves Steam's existing LaunchOptions field untouched.
-  launchOptionsData =
-    let
-      perMod = lib.mapAttrsToList (_modName: mod: {
-        appId = toString mod.steamAppId;
-        inherit (mod) launchOptions;
-      }) cfg.mods;
-      grouped = lib.foldl' (
-        acc: e: acc // { ${e.appId} = (acc.${e.appId} or [ ]) ++ e.launchOptions; }
-      ) { } perMod;
-      nonEmpty = lib.filterAttrs (_appId: parts: parts != [ ]) grouped;
-      entries = lib.mapAttrsToList (appId: parts: {
-        steamAppId = lib.toInt appId;
-        launchOptions = (lib.concatStringsSep " " parts) + " %command%";
-      }) nonEmpty;
-    in
-    builtins.toJSON entries;
-
   python = pkgs.python3.withPackages (ps: [ ps.vdf ]);
 
   gameModsApply =
@@ -200,7 +155,6 @@ let
         import vdf
 
         MOD_DATA = json.loads(${lib.escapeShellArg modData})
-        LAUNCH_OPTIONS_DATA = json.loads(${lib.escapeShellArg launchOptionsData})
         BACKUP_SUFFIX = ".nix-backup"
 
 
@@ -334,82 +288,6 @@ let
             print(f"game-mods: {verb} {target}", file=sys.stderr)
 
 
-        def apply_launch_options():
-            """Write declarative launch options into Steam's localconfig.vdf.
-
-            Steam stores per-app launch options at:
-              userdata/<accountid>/config/localconfig.vdf
-              → UserLocalConfigStore → Software → Valve → Steam
-                → apps → "<appid>" → LaunchOptions
-
-            We iterate every userdata directory so multi-account setups work.
-            Writes are idempotent (skip when the value already matches).
-            An atomic write (temp + os.replace) avoids torn reads by Steam.
-            """
-            if not LAUNCH_OPTIONS_DATA:
-                print("game-mods: no launch options configured", file=sys.stderr)
-                return
-
-            steam_root = find_steam_root()
-            userdata_root = os.path.join(steam_root, "userdata")
-            if not os.path.isdir(userdata_root):
-                print(
-                    "game-mods: userdata dir not found, skipping launch options",
-                    file=sys.stderr,
-                )
-                return
-
-            for entry in LAUNCH_OPTIONS_DATA:
-                appid = str(entry["steamAppId"])
-                desired_lo = entry["launchOptions"]
-
-                for account_dir in sorted(os.listdir(userdata_root)):
-                    config_path = os.path.join(
-                        userdata_root, account_dir, "config", "localconfig.vdf"
-                    )
-                    if not os.path.isfile(config_path):
-                        continue
-
-                    try:
-                        with open(config_path, "r", errors="replace") as f:
-                            data = vdf.load(f, mapper=dict)
-                    except Exception as exc:
-                        print(
-                            f"game-mods: failed to parse {config_path}: {exc}",
-                            file=sys.stderr,
-                        )
-                        continue
-
-                    apps = (
-                        data.setdefault("UserLocalConfigStore", {})
-                        .setdefault("Software", {})
-                        .setdefault("Valve", {})
-                        .setdefault("Steam", {})
-                        .setdefault("apps", {})
-                    )
-                    app_block = apps.setdefault(appid, {})
-
-                    current_lo = app_block.get("LaunchOptions", "")
-                    if current_lo == desired_lo:
-                        continue  # already applied, skip write
-
-                    app_block["LaunchOptions"] = desired_lo
-
-                    tmp_path = config_path + ".tmp"
-                    with open(tmp_path, "w") as f:
-                        vdf.dump(data, f, pretty=True)
-                    os.replace(tmp_path, config_path)
-
-                    print(
-                        f"game-mods: set launch options for app {appid}"
-                        f" in account {account_dir}:"
-                        f" {desired_lo!r}",
-                        file=sys.stderr,
-                    )
-
-            print("game-mods: launch options done", file=sys.stderr)
-
-
         def main():
             if MOD_DATA:
                 for entry in MOD_DATA:
@@ -420,9 +298,6 @@ let
                         entry["mode"],
                         entry["location"],
                     )
-
-            apply_launch_options()
-
             print("game-mods: done", file=sys.stderr)
 
 
@@ -457,12 +332,13 @@ in
         "media-games.mount"
         "local-fs.target"
       ];
-      # Hash of the materialized mod manifest. Embedding it as a custom [Unit]
+      # Re-run on every config change. The unit is Type=oneshot with
-      # field forces the unit text to change whenever any mod entry, source
+      # RemainAfterExit=no, so it goes inactive after each apply; switch-to-
-      # path, mode, or location changes — so `switch-to-configuration switch`
+      # configuration restarts it (which re-runs the ExecStart) when the hash
-      # re-runs the apply step on the same boot instead of waiting for the
+      # of any trigger changes — picking up new mod entries, source paths,
-      # next daily timer firing. systemd ignores X- prefixed unit fields.
+      # modes, and locations on the same boot rather than waiting for the
-      unitConfig.X-ConfigHash = builtins.hashString "sha256" (modData + launchOptionsData);
+      # daily timer.
+      restartTriggers = [ modData ];
       serviceConfig = {
         Type = "oneshot";
         ExecStart = "${gameModsApply}/bin/game-mods-apply";