Automate Battle.net client tweaks via home activation

modules/home/battlenet.nix

@@ -0,0 +1,48 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+with lib;
+let
+  cfg = config.modules.battlenet;
+  yq = "${pkgs.yq}/bin/yq";
+  jq = "${pkgs.jq}/bin/jq";
+in
+{
+  config = mkIf cfg.enable {
+    # Battle.net is installed manually through Lutris, which creates the game
+    # config and wine prefix outside of Home Manager's control. The Lutris
+    # installer script writes HardwareAcceleration "false" (software rendering,
+    # which breaks Battle.net's CEF UI repainting under XWayland), so patch it
+    # and the game env after every rebuild. Re-run the rebuild after installing
+    # Battle.net for these tweaks to land.
+    home.activation.battlenetClientTweaks = hm.dag.entryAfter [ "writeBoundary" ] ''
+      shopt -s nullglob
+      for game in "$HOME"/.local/share/lutris/games/battlenet*.yml; do
+        prefix=$(${yq} -r '.game.prefix // ""' "$game" 2>/dev/null) || continue
+
+        for configFile in "$prefix"/drive_c/users/*/AppData/Roaming/Battle.net/Battle.net.config; do
+          [ -e "$configFile" ] || continue
+          if [ "$(${jq} -r '.Client.HardwareAcceleration // ""' "$configFile" 2>/dev/null)" != "true" ]; then
+            ${jq} '.Client.HardwareAcceleration = "true"' "$configFile" > "$configFile.tmp" && mv "$configFile.tmp" "$configFile"
+          fi
+        done
+
+        # GE-Proton's Wayland driver breaks Battle.net's CEF window sizing and
+        # painting, and Xalia misrenders the client, so pin both off.
+        if [ "$(${yq} -r '.system.env.PROTON_USE_XALIA // ""' "$game" 2>/dev/null)" != "0" ]; then
+          ${yq} --in-place --yaml-output '.system.env.PROTON_USE_XALIA = "0"' "$game"
+        fi
+        if [ "$(${yq} -r '.system.env.WINE_SIMULATE_WRITECOPY // ""' "$game" 2>/dev/null)" != "1" ]; then
+          ${yq} --in-place --yaml-output '.system.env.WINE_SIMULATE_WRITECOPY = "1"' "$game"
+        fi
+        if [ -n "$(${yq} -r '.system.env.PROTON_ENABLE_WAYLAND // ""' "$game" 2>/dev/null)" ]; then
+          ${yq} --in-place --yaml-output 'del(.system.env.PROTON_ENABLE_WAYLAND)' "$game"
+        fi
+      done
+      shopt -u nullglob
+    '';
+  };
+}

modules/home/default.nix

@@ -3,6 +3,7 @@
 }:
 {
   imports = [
+    ./battlenet.nix
     ./direnv.nix
     ./discord.nix
     ./dictation.nix