... this takes care of the current command also appearing in the history

src/cascadia/TerminalControl/ControlCore.cpp

@@ -2246,19 +2246,28 @@ namespace winrt::Microsoft::Terminal::Control::implementation
             return winrt::hstring{ L"" };
         };
 
+        const auto currentCommand = _terminal->CurrentCommand();
+        const auto trimmedCurrentCommand = trimToHstring(currentCommand);
+
         for (const auto& commandInBuffer : bufferCommands)
         {
-            if (const auto hstr {trimToHstring(commandInBuffer)} ; !hstr.empty() )
+            if (const auto hstr{ trimToHstring(commandInBuffer) };
+                (!hstr.empty() && hstr != trimmedCurrentCommand))
             {
                 commands.push_back(hstr);
             }
         }
 
-        auto context = winrt::make_self<CommandHistoryContext>(std::move(commands));
-
-        const auto currentCommand = _terminal->CurrentCommand();
-        context->CurrentCommandline(trimToHstring(currentCommand));
+        // If the very last thing in the list of recent commands, is exacly the
+        // same as the current command, then let's not include it in the
+        // history. It's literally the thing the user has typed, RIGHT now.
+        if (commands.back() == trimmedCurrentCommand)
+        {
+            commands.pop_back();
+        }
 
+        auto context = winrt::make_self<CommandHistoryContext>(std::move(commands));
+        context->CurrentCommandline(trimmedCurrentCommand);
         return *context;
     }
 

src/cascadia/UnitTests_Control/ControlCoreTests.cpp

@@ -543,8 +543,8 @@ namespace ControlUnitTests
         Log::Comment(L"Write 'Bar' to the command...");
         conn->WriteInput(L"Bar");
         {
-            DebugBreak();
             auto historyContext{ core->CommandHistory() };
+            // Bar shouldn't be in the history, it should be the current command
             VERIFY_ARE_EQUAL(1u, historyContext.History().Size());
             VERIFY_ARE_EQUAL(L"Bar", historyContext.CurrentCommandline());
         }
@@ -556,6 +556,7 @@ namespace ControlUnitTests
         {
             auto historyContext{ core->CommandHistory() };
             VERIFY_ARE_EQUAL(1u, historyContext.History().Size());
+            // The current commandline is now empty
             VERIFY_ARE_EQUAL(L"", historyContext.CurrentCommandline());
         }
     }