Give the Steam Frame's native build the standalone headset defaults

MKW_VR_STANDALONE (runtime_config.h) names the standalone headsets: the
Quest, and the Steam Frame in its Android flavour and its native SteamOS
build. They share render scale 0.8, foveation medium, the GX thread,
the game's object culling, and the headset panel's foveation and
tracked-hands rows; passthrough stays Quest-only.

The Frame's native build also sets AuroraConfig::xrHeadsetOnly, so
Aurora neither presents the desktop window nobody watches nor renders
it past the last pass the eyes sample, which Android does always (4 to
6 ms of a 12 ms GPU frame on a Quest 3).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019HBRGKTE1GnN2ah8gcZKr3

runtime/src/settings_overlay.cpp

@@ -146,8 +146,8 @@ bool g_vrHudVirtualScreen = RuntimeConfigFile::VrHudVirtualScreen(true);
 int g_vrRaceView = static_cast<int>(RuntimeConfigFile::GetVrRaceView());
 bool g_vrFlatScreen = g_vrRaceView == static_cast<int>(RuntimeConfigFile::VrRaceView::FlatScreen);
 constexpr std::array<const char*, 3> kVrRaceViewLabels{"Immersive", "Immersive window", "Flat screen"};
-#if defined(__ANDROID__)
-#if !defined(MKW_HEADSET_STEAM_FRAME)
+#if defined(MKW_VR_STANDALONE)
+#if defined(__ANDROID__) && !defined(MKW_HEADSET_STEAM_FRAME)
 bool g_vrPassthrough = RuntimeConfigFile::VrPassthrough();
 #endif
 bool g_vrHandTracking = RuntimeConfigFile::VrHandTracking();
@@ -1260,7 +1260,7 @@ void DrawVrSteeringWheelSettings() {
                           "trailed item.");
     }
     ImGui::EndDisabled();
-#if defined(__ANDROID__)
+#if defined(MKW_VR_STANDALONE)
     ImGui::BeginDisabled(!g_vrHandSteering && g_vrCockpitItemHand == 2);
     if (ImGui::Checkbox("Tracked hands", &g_vrHandTracking)) {
         RuntimeConfigFile::SetVrHandTracking(g_vrHandTracking);
@@ -1491,8 +1491,8 @@ void DrawVrSettings() {
                                 eyes.scaled_height, g_vrRenderScalePercent);
         }
     }
-#if defined(__ANDROID__)
-#if !defined(MKW_HEADSET_STEAM_FRAME)
+#if defined(MKW_VR_STANDALONE)
+#if defined(__ANDROID__) && !defined(MKW_HEADSET_STEAM_FRAME)
     if (ImGui::Checkbox("Passthrough around the menu screen", &g_vrPassthrough)) {
         mkw::vr::OpenXRSetPassthrough(g_vrPassthrough);
         RuntimeConfigFile::SetVrPassthrough(g_vrPassthrough);
@@ -1829,7 +1829,7 @@ void DrawVrCameraSettings() {
         RuntimeConfigFile::SetVrHandSteering(g_vrHandSteering);
         RuntimeConfigFile::SetVrCockpitItemHand(RuntimeConfigFile::kVrCockpitItemHandDefault);
         RuntimeConfigFile::SetVrCockpitItemThrow(g_vrCockpitItemThrow);
-#if defined(__ANDROID__)
+#if defined(MKW_VR_STANDALONE)
         g_vrHandTracking = RuntimeConfigFile::kVrHandTrackingDefault;
         RuntimeConfigFile::SetVrHandTracking(g_vrHandTracking);
 #endif
@@ -2531,7 +2531,7 @@ void InitializeRuntimeSettings() noexcept {
     aurora_set_display_mode(static_cast<AuroraDisplayMode>(g_displayMode));
     g_displayMode = static_cast<int>(aurora_get_display_mode());
     aurora_set_disable_copy_filter(g_disableCopyFilter);
-#if defined(__ANDROID__)
+#if defined(MKW_VR_STANDALONE)
     aurora_set_stereo_foveation(static_cast<uint32_t>(g_vrFoveation));
 #endif
     aurora_set_stereo_mirror_view(static_cast<AuroraStereoMirrorView>(g_vrMirrorView));

runtime/src/vr/openxr_integration.cpp

@@ -745,6 +745,11 @@ private:
         // launched with foveation off does without them.
         aurora_config.xrFragmentDensityMap = RuntimeConfigFile::VrFoveation() != "off";
 #endif
+#if defined(MKW_HEADSET_STEAM_FRAME) && !defined(__ANDROID__)
+        // The Frame's native build: the headset is the only display anyone looks at, so the
+        // desktop window is neither presented nor fully rendered, as on Android.
+        aurora_config.xrHeadsetOnly = true;
+#endif
 #if defined(_WIN32)
         if (kRequiredAuroraBackend != BACKEND_D3D12) return;
         const auto& requirements = backend_->GraphicsRequirements();