Fix scrollbar marks not appearing until scroll or resize (#19185)

This PR resolves an issue where scrollbar marks created by shell
integration sequences (OSC 133 FTCS, OSC 1337 iTerm2, and OSC 9;12
ConEmu sequences) were not visible on the scrollbar until the user
manually scrolled.

The problem was that while marks were being created in the buffer
correctly, the UI wasn't being notified to refresh the scrollbar
display. The fix adds a new NotifyShellIntegrationMark() method to the
ITerminalApi interface that calls _NotifyScrollEvent() to trigger
scrollbar refresh, and updates all shell integration sequence handlers
in AdaptDispatch to call this notification method after creating marks.
This ensures scrollbar marks appear immediately when shell integration
sequences are processed, bringing feature parity between auto-detected
and shell-integration-based marks.

Closes #19104

Author: killerdevildog

src/cascadia/TerminalCore/Terminal.hpp

@@ -156,6 +156,7 @@ class Microsoft::Terminal::Core::Terminal final :
     bool IsVtInputEnabled() const noexcept override;
     void NotifyAccessibilityChange(const til::rect& changedRect) noexcept override;
     void NotifyBufferRotation(const int delta) override;
+    void NotifyShellIntegrationMark() override;
 
     void InvokeCompletions(std::wstring_view menuJson, unsigned int replaceLength) override;
 

src/cascadia/TerminalCore/TerminalApi.cpp

@@ -404,3 +404,9 @@ void Terminal::NotifyBufferRotation(const int delta)
         _NotifyScrollEvent();
     }
 }
+
+void Terminal::NotifyShellIntegrationMark()
+{
+    // Notify the scrollbar that marks have been added so it can refresh the mark indicators
+    _NotifyScrollEvent();
+}

src/host/outputStream.cpp

@@ -446,6 +446,11 @@ void ConhostInternalGetSet::NotifyBufferRotation(const int delta)
     }
 }
 
+void ConhostInternalGetSet::NotifyShellIntegrationMark()
+{
+    // Not implemented for conhost - shell integration marks are a Terminal app feature.
+}
+
 void ConhostInternalGetSet::InvokeCompletions(std::wstring_view /*menuJson*/, unsigned int /*replaceLength*/)
 {
     // Not implemented for conhost.

src/host/outputStream.hpp

@@ -67,6 +67,7 @@ class ConhostInternalGetSet final : public Microsoft::Console::VirtualTerminal::
 
     void NotifyAccessibilityChange(const til::rect& changedRect) override;
     void NotifyBufferRotation(const int delta) override;
+    void NotifyShellIntegrationMark() override;
 
     void InvokeCompletions(std::wstring_view menuJson, unsigned int replaceLength) override;
 

src/terminal/adapter/ITerminalApi.hpp

@@ -86,6 +86,7 @@ namespace Microsoft::Console::VirtualTerminal
 
         virtual void NotifyAccessibilityChange(const til::rect& changedRect) = 0;
         virtual void NotifyBufferRotation(const int delta) = 0;
+        virtual void NotifyShellIntegrationMark() = 0;
 
         virtual void InvokeCompletions(std::wstring_view menuJson, unsigned int replaceLength) = 0;
 

src/terminal/adapter/adaptDispatch.cpp

@@ -3600,6 +3600,7 @@ void AdaptDispatch::DoConEmuAction(const std::wstring_view string)
     else if (subParam == 12)
     {
         _pages.ActivePage().Buffer().StartCommand();
+        _api.NotifyShellIntegrationMark();
     }
 }
 
@@ -3630,6 +3631,7 @@ void AdaptDispatch::DoITerm2Action(const std::wstring_view string)
     if (action == L"SetMark")
     {
         _pages.ActivePage().Buffer().StartPrompt();
+        _api.NotifyShellIntegrationMark();
     }
 }
 
@@ -3663,16 +3665,19 @@ void AdaptDispatch::DoFinalTermAction(const std::wstring_view string)
         case L'A': // FTCS_PROMPT
         {
             _pages.ActivePage().Buffer().StartPrompt();
+            _api.NotifyShellIntegrationMark();
             break;
         }
         case L'B': // FTCS_COMMAND_START
         {
             _pages.ActivePage().Buffer().StartCommand();
+            _api.NotifyShellIntegrationMark();
             break;
         }
         case L'C': // FTCS_COMMAND_EXECUTED
         {
             _pages.ActivePage().Buffer().StartOutput();
+            _api.NotifyShellIntegrationMark();
             break;
         }
         case L'D': // FTCS_COMMAND_FINISHED
@@ -3693,6 +3698,7 @@ void AdaptDispatch::DoFinalTermAction(const std::wstring_view string)
             }
 
             _pages.ActivePage().Buffer().EndCurrentCommand(error);
+            _api.NotifyShellIntegrationMark();
 
             break;
         }

src/terminal/adapter/ut_adapter/adapterTest.cpp

@@ -212,6 +212,11 @@ class TestGetSet final : public ITerminalApi
         Log::Comment(L"NotifyBufferRotation MOCK called...");
     }
 
+    void NotifyShellIntegrationMark() override
+    {
+        Log::Comment(L"NotifyShellIntegrationMark MOCK called...");
+    }
+
     void InvokeCompletions(std::wstring_view menuJson, unsigned int replaceLength) override
     {
         Log::Comment(L"InvokeCompletions MOCK called...");