Detect native-Linux Stardew Valley, default executables to no-Proton

Add IPluginGame::isNativeLinux() (virtual, default false) so a plugin
can advertise that the discovered installation is a native Linux build.
Bound through the Python plugin trampoline so basic_games subclasses can
override it.

Stardew Valley plugin: when the install dir contains the StardewValley
launcher script and no Stardew Valley.exe, report isNativeLinux=true and
return Linux-side binary names (StardewValley, StardewModdingAPI). Also
fix GameDataPath to "Mods" — Linux ships the SMAPI mods dir with a
capital M.

ExecutablesList::getPluginExecutables: skip the UseProton flag when the
plugin reports native Linux, so the spawn path falls into launchDirect()
and the game runs without a Wine prefix.

4 files changed, 48 insertions, 2 deletions

diff --git a/libs/basic_games/games/game_stardewvalley.py b/libs/basic_games/games/game_stardewvalley.py
index 6397b40..566a511 100644
--- a/libs/basic_games/games/game_stardewvalley.py
+++ b/libs/basic_games/games/game_stardewvalley.py
@@ -1,4 +1,6 @@
-from PyQt6.QtCore import QFileInfo
+import sys
+
+from PyQt6.QtCore import QDir, QFileInfo
 
 import mobase
 
@@ -21,6 +23,17 @@ class StardewValleyModDataChecker(mobase.ModDataChecker):
         return mobase.ModDataChecker.INVALID
 
 
+def _has_native_linux_install(game_dir: QDir) -> bool:
+    # Native Linux Stardew ships a `StardewValley` shell-script launcher and
+    # has no `Stardew Valley.exe`.  Use that to distinguish from a Windows
+    # install dropped under a Wine prefix.
+    if sys.platform != "linux":
+        return False
+    if QFileInfo(game_dir, "Stardew Valley.exe").exists():
+        return False
+    return QFileInfo(game_dir, "StardewValley").exists()
+
+
 class StardewValleyGame(BasicGame):
     Name = "Stardew Valley Support Plugin"
     Author = "Syer10"
@@ -33,7 +46,7 @@ class StardewValleyGame(BasicGame):
     GameSteamId = 413150
     GameGogId = 1453375253
     GameBinary = "Stardew Valley.exe"
-    GameDataPath = "mods"
+    GameDataPath = "Mods"
     GameDocumentsDirectory = "%DOCUMENTS%/StardewValley"
     GameSavesDirectory = "%GAME_DOCUMENTS%/Saves"
     GameSupportURL = (
@@ -46,7 +59,26 @@ class StardewValleyGame(BasicGame):
         self._register_feature(StardewValleyModDataChecker())
         return True
 
+    def isNativeLinux(self) -> bool:
+        return _has_native_linux_install(self.gameDirectory())
+
+    def binaryName(self) -> str:
+        if self.isNativeLinux():
+            return "StardewValley"
+        return super().binaryName()
+
     def executables(self):
+        if self.isNativeLinux():
+            return [
+                mobase.ExecutableInfo(
+                    "SMAPI",
+                    QFileInfo(self.gameDirectory(), "StardewModdingAPI"),
+                ),
+                mobase.ExecutableInfo(
+                    "Stardew Valley",
+                    QFileInfo(self.gameDirectory(), "StardewValley"),
+                ),
+            ]
         return [
             mobase.ExecutableInfo(
                 "SMAPI", QFileInfo(self.gameDirectory(), "StardewModdingAPI.exe")
diff --git a/libs/plugin_python/src/mobase/wrappers/pyplugins.cpp b/libs/plugin_python/src/mobase/wrappers/pyplugins.cpp
index bcce0df..c744c7b 100644
--- a/libs/plugin_python/src/mobase/wrappers/pyplugins.cpp
+++ b/libs/plugin_python/src/mobase/wrappers/pyplugins.cpp
@@ -52,6 +52,7 @@ namespace mo2::python {
                  "settings"_a)
             .def("listSaves", &IPluginGame::listSaves, "folder"_a)
             .def("isInstalled", &IPluginGame::isInstalled)
+            .def("isNativeLinux", &IPluginGame::isNativeLinux)
             .def("gameIcon", &IPluginGame::gameIcon)
             .def("gameDirectory", &IPluginGame::gameDirectory)
             .def("dataDirectory", &IPluginGame::dataDirectory)
diff --git a/libs/plugin_python/src/mobase/wrappers/pyplugins.h b/libs/plugin_python/src/mobase/wrappers/pyplugins.h
index 17f7ab5..ce9a911 100644
--- a/libs/plugin_python/src/mobase/wrappers/pyplugins.h
+++ b/libs/plugin_python/src/mobase/wrappers/pyplugins.h
@@ -385,6 +385,10 @@ namespace mo2::python {
         {
             PYBIND11_OVERRIDE_PURE(bool, IPluginGame, isInstalled, );
         }
+        bool isNativeLinux() const override
+        {
+            PYBIND11_OVERRIDE(bool, IPluginGame, isNativeLinux, );
+        }
         QIcon gameIcon() const override
         {
             PYBIND11_OVERRIDE_PURE(QIcon, IPluginGame, gameIcon, );
diff --git a/libs/uibase/include/uibase/iplugingame.h b/libs/uibase/include/uibase/iplugingame.h
index 0fa2508..93ee09f 100644
--- a/libs/uibase/include/uibase/iplugingame.h
+++ b/libs/uibase/include/uibase/iplugingame.h
@@ -145,6 +145,15 @@ public:
   /**
    * this function may be called before init()
    *
+   * @return true if the discovered installation is a native Linux build that
+   *         should be launched directly without Proton/Wine.  Default false:
+   *         Linux ports of MO2 historically run every game under Proton.
+   */
+  virtual bool isNativeLinux() const { return false; }
+
+  /**
+   * this function may be called before init()
+   *
    * @return an icon for this game
    */
   virtual QIcon gameIcon() const = 0;