Fix for SDL stalling the pacing thread

runtime/include/vr/openxr_input.h

@@ -76,8 +76,10 @@ struct OpenXRPointerScreen {
 // Lifetime: Create after the session exists (attaches the action set, which
 // OpenXR permits once per session), Sync once per xrWaitFrame, Idle while the
 // session is not running, Destroy before the session is destroyed. All of them
-// run on the XR pacing thread; SDL's virtual joystick setters and the Wii
-// Remote bridge are internally locked, so the game thread may read concurrently.
+// run on the XR pacing thread. The Wii Remote bridge is internally locked, so
+// the game thread may read it concurrently, and the virtual gamepad is only
+// published here: OpenXRApplyVirtualGamepad() performs the SDL writes on the
+// game thread, keeping SDL's joystick lock off this thread entirely.
 class OpenXRInput final {
 public:
     explicit OpenXRInput(OpenXRLogCallback logger = {});
@@ -185,6 +187,10 @@ private:
     std::string m_last_error;
 };
 
+// Game thread: writes the gamepad the pacing thread last published, if any.
+// Does nothing when no OpenXR controllers are attached.
+void OpenXRApplyVirtualGamepad() noexcept;
+
 } // namespace mkw::vr
 
 #endif // defined(MKW_ENABLE_OPENXR)

runtime/include/vr/openxr_integration.h

@@ -34,6 +34,13 @@ void OpenXRShutdownBeforeAurora() noexcept;
 void OpenXRServiceProducerFrameBoundary() noexcept;
 
 bool OpenXRIsRunning() noexcept;
+
+// Writes the controllers the pacing thread last published to the virtual
+// gamepad. Call it from the thread that polls controllers, wherever the game
+// is about to read them: the pacing thread deliberately leaves SDL alone, since
+// SDL's joystick lock is held for the length of a device enumeration and an
+// OpenXR frame may not wait that long. Cheap and safe to call when VR is off.
+void OpenXRApplyControllerState() noexcept;
 std::string OpenXRLastError();
 
 // Recenters on where the player is sitting now: it moves the immersive race