Make disabling the Kitty Keyboard Protocol possible (#19995)

Avoid translating W32IM sequences to KKP.

Closes #19977

## Validation Steps Performed
* Use French Bepo keyboard layout
* Disable KKP
* Use fish shell
* `AltGr+Y` produces `{` ✅

Author: lhecker

src/cascadia/TerminalCore/Terminal.hpp

@@ -132,6 +132,7 @@ class Microsoft::Terminal::Core::Terminal final :
 #pragma region ITerminalApi
     // These methods are defined in TerminalApi.cpp
     void ReturnResponse(const std::wstring_view response) override;
+    bool IsConPTY() const noexcept override;
     Microsoft::Console::VirtualTerminal::StateMachine& GetStateMachine() noexcept override;
     BufferState GetBufferAndViewport() noexcept override;
     void SetViewportPosition(const til::point position) noexcept override;

src/cascadia/TerminalCore/TerminalApi.cpp

@@ -28,6 +28,11 @@ void Terminal::ReturnResponse(const std::wstring_view response)
     }
 }
 
+bool Terminal::IsConPTY() const noexcept
+{
+    return false;
+}
+
 Microsoft::Console::VirtualTerminal::StateMachine& Terminal::GetStateMachine() noexcept
 {
     return *_stateMachine;

src/host/outputStream.cpp

@@ -48,6 +48,12 @@ void ConhostInternalGetSet::ReturnResponse(const std::wstring_view response)
     _io.GetActiveInputBuffer()->WriteString(response);
 }
 
+bool ConhostInternalGetSet::IsConPTY() const noexcept
+{
+    const auto& gci = ServiceLocator::LocateGlobals().getConsoleInformation();
+    return gci.IsInVtIoMode();
+}
+
 // Routine Description:
 // - Retrieves the state machine for the active output buffer.
 // Arguments:

src/host/outputStream.hpp

@@ -31,6 +31,7 @@ class ConhostInternalGetSet final : public Microsoft::Console::VirtualTerminal::
 
     void ReturnResponse(const std::wstring_view response) override;
 
+    bool IsConPTY() const noexcept override;
     Microsoft::Console::VirtualTerminal::StateMachine& GetStateMachine() override;
     BufferState GetBufferAndViewport() override;
     void SetViewportPosition(const til::point position) override;

src/terminal/adapter/ITerminalApi.hpp

@@ -46,6 +46,7 @@ namespace Microsoft::Console::VirtualTerminal
             bool isMainBuffer;
         };
 
+        virtual bool IsConPTY() const noexcept = 0;
         virtual StateMachine& GetStateMachine() = 0;
         virtual BufferState GetBufferAndViewport() = 0;
         virtual void SetViewportPosition(const til::point position) = 0;

src/terminal/adapter/adaptDispatch.cpp

@@ -2073,6 +2073,13 @@ void AdaptDispatch::SetAnsiMode(const bool ansiMode)
 // CSI = flags ; mode u - Sets kitty keyboard protocol flags
 void AdaptDispatch::SetKittyKeyboardProtocol(const VTParameter flags, const VTParameter mode) noexcept
 {
+    // Avoid setting KKP flags in `_terminalInput` when we're ConPTY. Otherwise, we'd be translating
+    // W32IM to KKP, even when KKP is not supported by the hosting terminal (possibly intentionally).
+    if (_api.IsConPTY())
+    {
+        return;
+    }
+
     const auto kittyFlags = gsl::narrow_cast<uint8_t>(flags.value_or(0));
     const auto KittyKeyboardProtocol = static_cast<TerminalInput::KittyKeyboardProtocolMode>(mode.value_or(1));
     _terminalInput.SetKittyKeyboardProtocol(kittyFlags, KittyKeyboardProtocol);
@@ -2081,20 +2088,35 @@ void AdaptDispatch::SetKittyKeyboardProtocol(const VTParameter flags, const VTPa
 // CSI ? u - Queries current kitty keyboard protocol flags
 void AdaptDispatch::QueryKittyKeyboardProtocol()
 {
+    if (_api.IsConPTY())
+    {
+        return;
+    }
+
     const auto flags = static_cast<VTInt>(_terminalInput.GetKittyFlags());
     _ReturnCsiResponse(fmt::format(FMT_COMPILE(L"?{}u"), flags));
 }
 
 // CSI > flags u - Pushes current kitty keyboard flags onto the stack and sets new flags
 void AdaptDispatch::PushKittyKeyboardProtocol(const VTParameter flags)
 {
+    if (_api.IsConPTY())
+    {
+        return;
+    }
+
     const auto kittyFlags = gsl::narrow_cast<uint8_t>(flags.value_or(0));
     _terminalInput.PushKittyFlags(kittyFlags);
 }
 
 // CSI < count u - Pops one or more entries from the kitty keyboard stack
 void AdaptDispatch::PopKittyKeyboardProtocol(const VTParameter count)
 {
+    if (_api.IsConPTY())
+    {
+        return;
+    }
+
     const auto popCount = static_cast<size_t>(count.value_or(1));
     _terminalInput.PopKittyFlags(popCount);
 }

src/terminal/adapter/ut_adapter/adapterTest.cpp

@@ -76,6 +76,11 @@ class TestGetSet final : public ITerminalApi
         }
     }
 
+    bool IsConPTY() const noexcept override
+    {
+        return false;
+    }
+
     StateMachine& GetStateMachine() override
     {
         return *_stateMachine;

src/terminal/input/terminalInput.cpp

@@ -228,7 +228,8 @@ TerminalInput::OutputType TerminalInput::HandleKey(const INPUT_RECORD& event)
     // GH#4999 - If we're in win32-input mode, skip straight to doing that.
     // Since this mode handles all types of key events, do nothing else.
     //
-    // The kitty keyboard protocol takes precedence, because it's cross-platform.
+    // ConPTY assumes that W32IM always remains enabled. We have to prefer
+    // the kitty keyboard protocol, because otherwise it would never be used.
     if (_inputMode.test(Mode::Win32) && !_forceDisableWin32InputMode && !_kittyFlags)
     {
         return _makeWin32Output(event.Event.KeyEvent);