Fix cabextract not found in pressure-vessel and TTW game detection

cabextract: The system binary under /usr is invisible inside the
pressure-vessel container where winetricks runs. Always download a
local copy to ~/.local/share/fluorine/bin/ instead of short-circuiting
when the host has it installed.

TTW: The game plugin was calling the base class identifyGamePath()
which tried matching "TTW" against NaK's detected game names — never
matching "Fallout New Vegas". Now explicitly searches for FNV in the
NaK results, mirroring how the Windows path uses the FalloutNV registry
key. Also adds HAS_NAK_FFI and nak_ffi linkage to the TTW CMake target
since it was previously only defined for the game_gamebryo target.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

2 files changed, 32 insertions, 2 deletions

diff --git a/libs/game_bethesda/src/games/ttw/CMakeLists.txt b/libs/game_bethesda/src/games/ttw/CMakeLists.txt
index 27149ec..828b67f 100644
--- a/libs/game_bethesda/src/games/ttw/CMakeLists.txt
+++ b/libs/game_bethesda/src/games/ttw/CMakeLists.txt
@@ -17,4 +17,11 @@ add_library(game_ttw SHARED
 mo2_configure_plugin(game_ttw NO_SOURCES WARNINGS 4)
 mo2_default_source_group()
 target_link_libraries(game_ttw PRIVATE game_gamebryo)
+
+# NaK FFI for TTW game detection (TTW uses FalloutNV as base game)
+if(TARGET mo2::nak_ffi)
+    target_link_libraries(game_ttw PRIVATE mo2::nak_ffi)
+    target_compile_definitions(game_ttw PRIVATE HAS_NAK_FFI)
+endif()
+
 mo2_install_plugin(game_ttw)
diff --git a/libs/game_bethesda/src/games/ttw/gamefalloutttw.cpp b/libs/game_bethesda/src/games/ttw/gamefalloutttw.cpp
index 3ffa5a1..cfd8ca8 100644
--- a/libs/game_bethesda/src/games/ttw/gamefalloutttw.cpp
+++ b/libs/game_bethesda/src/games/ttw/gamefalloutttw.cpp
@@ -15,6 +15,11 @@
 #include <gamebryosavegameinfo.h>
 #include <gamebryounmanagedmods.h>
 
+#ifdef HAS_NAK_FFI
+#include <nak_ffi.h>
+#include "scopeguard.h"
+#endif
+
 #include <QCoreApplication>
 #include <QDir>
 #include <QFileInfo>
@@ -80,8 +85,26 @@ QString GameFalloutTTW::identifyGamePath() const
   QString path = "Software\\Bethesda Softworks\\FalloutNV";
   result       = findInRegistry(HKEY_LOCAL_MACHINE, path.toStdWString().c_str(),
                                 L"Installed Path");
-#else
-  result = GameGamebryo::identifyGamePath();
+#elif defined(HAS_NAK_FFI)
+  // TTW uses FalloutNV as its base game, so look for Fallout New Vegas
+  // (the base class would try matching "TTW" which NaK doesn't know about)
+  NakGameList gameList = nak_detect_all_games();
+  ON_BLOCK_EXIT([&]() {
+    nak_game_list_free(gameList);
+  });
+
+  for (size_t i = 0; i < gameList.count; ++i) {
+    const NakGame& game = gameList.games[i];
+    QString detectedName = QString::fromUtf8(game.name);
+    if (detectedName.contains("Fallout", Qt::CaseInsensitive) &&
+        detectedName.contains("Vegas", Qt::CaseInsensitive)) {
+      QString detectedPath = QString::fromUtf8(game.install_path);
+      if (looksValid(QDir(detectedPath))) {
+        result = detectedPath;
+        break;
+      }
+    }
+  }
 #endif
   // EPIC Game Store
   if (result.isEmpty()) {