Use RenderSettings for DECSET 2026 - Synchronized Output (#18833)

`RenderSettings` already stores `DECSCNM` (reversed screen),
so it only makes sense to also store DECSET 2026 there.

## Validation Steps Performed
* Same as in #18826 ✅

src/cascadia/TerminalControl/ControlCore.cpp

@@ -143,7 +143,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         // the UIA Engine to the renderer. This prevents us from signaling changes to the cursor or buffer.
         {
             // Now create the renderer and initialize the render thread.
-            const auto& renderSettings = _terminal->GetRenderSettings();
+            auto& renderSettings = _terminal->GetRenderSettings();
             _renderer = std::make_unique<::Microsoft::Console::Render::Renderer>(renderSettings, _terminal.get());
 
             _renderer->SetBackgroundColorChangedCallback([this]() { _rendererBackgroundColorChanged(); });

src/renderer/base/RenderSettings.cpp

@@ -46,9 +46,9 @@ void RenderSettings::RestoreDefaultSettings() noexcept
 {
     _colorTable = _defaultColorTable;
     _colorAliasIndices = _defaultColorAliasIndices;
-    // For now, DECSCNM is the only render mode we need to reset. The others are
+    // DECSCNM and Synchronized Output are the only render mode we need to reset.
-    // all user preferences that can't be changed programmatically.
+    // The others are all user preferences that can't be changed programmatically.
-    _renderMode.reset(Mode::ScreenReversed);
+    _renderMode.reset(Mode::ScreenReversed, Mode::SynchronizedOutput);
 }
 
 // Routine Description:

src/renderer/base/renderer.cpp

@@ -25,7 +25,7 @@ static constexpr auto renderBackoffBaseTimeMilliseconds{ 150 };
 // - pData - The interface to console data structures required for rendering
 // Return Value:
 // - An instance of a Renderer.
-Renderer::Renderer(const RenderSettings& renderSettings, IRenderData* pData) :
+Renderer::Renderer(RenderSettings& renderSettings, IRenderData* pData) :
     _renderSettings(renderSettings),
     _pData(pData)
 {
@@ -187,17 +187,21 @@ void Renderer::NotifyPaintFrame() noexcept
 }
 
 // NOTE: You must be holding the console lock when calling this function.
-void Renderer::SynchronizedOutputBegin() noexcept
+void Renderer::SynchronizedOutputChanged() noexcept
 {
-    // Kick the render thread into calling `_synchronizeWithOutput()`.
+    const auto so = _renderSettings.GetRenderMode(RenderSettings::Mode::SynchronizedOutput);
-    _isSynchronizingOutput = true;
+    if (_isSynchronizingOutput == so)
-}
+    {
+        return;
+    }
 
-// NOTE: You must be holding the console lock when calling this function.
+    // If `_isSynchronizingOutput` is true, it'll kick the
-void Renderer::SynchronizedOutputEnd() noexcept
+    // render thread into calling `_synchronizeWithOutput()`...
-{
+    _isSynchronizingOutput = so;
-    // Unblock `_synchronizeWithOutput()` from the `WaitOnAddress` call.
+
-    _isSynchronizingOutput = false;
+    if (!_isSynchronizingOutput)
+    {
+        // ...otherwise, unblock `_synchronizeWithOutput()` from the `WaitOnAddress` call.
         WakeByAddressSingle(&_isSynchronizingOutput);
 
         // It's crucial to give the render thread at least a chance to gain the lock.
@@ -212,6 +216,7 @@ void Renderer::SynchronizedOutputEnd() noexcept
         // Apps that use DECSET 2026 don't produce that sequence continuously, but rather at a fixed rate.
         _pData->UnlockConsole();
         _pData->LockConsole();
+    }
 }
 
 void Renderer::_synchronizeWithOutput() noexcept
@@ -249,6 +254,7 @@ void Renderer::_synchronizeWithOutput() noexcept
     // If a timeout occurred, `_isSynchronizingOutput` may still be true.
     // Set it to false now to skip calling `_synchronizeWithOutput()` on the next frame.
     _isSynchronizingOutput = false;
+    _renderSettings.SetRenderMode(RenderSettings::Mode::SynchronizedOutput, false);
 }
 
 // Routine Description:

src/renderer/base/renderer.hpp

@@ -28,15 +28,14 @@ namespace Microsoft::Console::Render
     class Renderer
     {
     public:
-        Renderer(const RenderSettings& renderSettings, IRenderData* pData);
+        Renderer(RenderSettings& renderSettings, IRenderData* pData);
 
         IRenderData* GetRenderData() const noexcept;
 
         [[nodiscard]] HRESULT PaintFrame();
 
         void NotifyPaintFrame() noexcept;
-        void SynchronizedOutputBegin() noexcept;
+        void SynchronizedOutputChanged() noexcept;
-        void SynchronizedOutputEnd() noexcept;
         void TriggerSystemRedraw(const til::rect* const prcDirtyClient);
         void TriggerRedraw(const Microsoft::Console::Types::Viewport& region);
         void TriggerRedraw(const til::point* const pcoord);
@@ -113,7 +112,7 @@ namespace Microsoft::Console::Render
         void _prepareNewComposition();
         [[nodiscard]] HRESULT _PrepareRenderInfo(_In_ IRenderEngine* const pEngine);
 
-        const RenderSettings& _renderSettings;
+        RenderSettings& _renderSettings;
         std::array<IRenderEngine*, 2> _engines{};
         IRenderData* _pData = nullptr; // Non-ownership pointer
         static constexpr size_t _firstSoftFontChar = 0xEF20;

src/renderer/inc/RenderSettings.hpp

@@ -25,7 +25,8 @@ namespace Microsoft::Console::Render
             AlwaysDistinguishableColors,
             IntenseIsBold,
             IntenseIsBright,
-            ScreenReversed
+            ScreenReversed,
+            SynchronizedOutput,
         };
 
         RenderSettings() noexcept;

src/terminal/adapter/adaptDispatch.cpp

@@ -1915,16 +1915,10 @@ void AdaptDispatch::_ModeParamsHelper(const DispatchTypes::ModeParams param, con
         _api.SetSystemMode(ITerminalApi::Mode::BracketedPaste, enable);
         break;
     case DispatchTypes::ModeParams::SO_SynchronizedOutput:
+        _renderSettings.SetRenderMode(RenderSettings::Mode::SynchronizedOutput, enable);
         if (_renderer)
         {
-            if (enable)
+            _renderer->SynchronizedOutputChanged();
-            {
-                _renderer->SynchronizedOutputBegin();
-            }
-            else
-            {
-                _renderer->SynchronizedOutputEnd();
-            }
         }
         break;
     case DispatchTypes::ModeParams::GCM_GraphemeClusterMode:
@@ -2065,6 +2059,9 @@ void AdaptDispatch::RequestMode(const DispatchTypes::ModeParams param)
     case DispatchTypes::ModeParams::XTERM_BracketedPasteMode:
         state = mapTemp(_api.GetSystemMode(ITerminalApi::Mode::BracketedPaste));
         break;
+    case DispatchTypes::ModeParams::SO_SynchronizedOutput:
+        state = mapTemp(_renderSettings.GetRenderMode(RenderSettings::Mode::SynchronizedOutput));
+        break;
     case DispatchTypes::ModeParams::GCM_GraphemeClusterMode:
         state = mapPerm(CodepointWidthDetector::Singleton().GetMode() == TextMeasurementMode::Graphemes);
         break;
@@ -3050,6 +3047,7 @@ void AdaptDispatch::HardReset()
     if (_renderer)
     {
         _renderer->TriggerRedrawAll(true, true);
+        _renderer->SynchronizedOutputChanged();
     }
 
     // Cursor to 1,1 - the Soft Reset guarantees this is absolute