Show parts of the scrollback on restore

src/cascadia/TerminalApp/TerminalPage.cpp

@@ -2994,15 +2994,6 @@ namespace winrt::TerminalApp::implementation
 
         const auto content = _manager.CreateCore(settings.DefaultSettings(), settings.UnfocusedSettings(), connection);
         const TermControl control{ content };
-
-        if (const auto id = settings.DefaultSettings().SessionId(); id != winrt::guid{})
-        {
-            const auto settingsDir = CascadiaSettings::SettingsDirectory();
-            const auto idStr = Utils::GuidToPlainString(id);
-            const auto path = fmt::format(FMT_COMPILE(L"{}\\buffer_{}.txt"), settingsDir, idStr);
-            control.RestoreFromPath(path);
-        }
-
         return _SetupControl(control);
     }
 
@@ -3102,7 +3093,10 @@ namespace winrt::TerminalApp::implementation
             return nullptr;
         }
 
-        auto connection = existingConnection ? existingConnection : _CreateConnectionFromSettings(profile, controlSettings.DefaultSettings(), false);
+        const auto sessionId = controlSettings.DefaultSettings().SessionId();
+        const auto hasSessionId = sessionId != winrt::guid{};
+
+        auto connection = existingConnection ? existingConnection : _CreateConnectionFromSettings(profile, controlSettings.DefaultSettings(), hasSessionId);
         if (existingConnection)
         {
             connection.Resize(controlSettings.DefaultSettings().InitialRows(), controlSettings.DefaultSettings().InitialCols());
@@ -3124,6 +3118,14 @@ namespace winrt::TerminalApp::implementation
 
         const auto control = _CreateNewControlAndContent(controlSettings, connection);
 
+        if (hasSessionId)
+        {
+            const auto settingsDir = CascadiaSettings::SettingsDirectory();
+            const auto idStr = Utils::GuidToPlainString(sessionId);
+            const auto path = fmt::format(FMT_COMPILE(L"{}\\buffer_{}.txt"), settingsDir, idStr);
+            control.RestoreFromPath(path);
+        }
+
         auto paneContent{ winrt::make<TerminalPaneContent>(profile, _terminalSettingsCache, control) };
 
         auto resultPane = std::make_shared<Pane>(paneContent);

src/cascadia/TerminalControl/ControlCore.cpp

@@ -1787,12 +1787,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
             // * prints "  [Restored <date> <time>]  <spaces until end of line>  "
             // * resets the color ("\x1b[m")
             // * newlines
-            // * clears the screen ("\x1b[2J")
-            // The last step is necessary because we launch ConPTY without PSEUDOCONSOLE_INHERIT_CURSOR by default.
-            // This will cause ConPTY to emit a \x1b[2J sequence on startup to ensure it and the terminal are in-sync.
-            // If we didn't do a \x1b[2J ourselves as well, the user would briefly see the last state of the terminal,
-            // before it's quickly scrolled away once ConPTY has finished starting up, which looks weird.
-            message = fmt::format(FMT_COMPILE(L"\x1b[100;37m  [{} {} {}]\x1b[K\x1b[m\r\n\x1b[2J"), msg, date, time);
+            message = fmt::format(FMT_COMPILE(L"\x1b[100;37m  [{} {} {}]\x1b[K\x1b[m\r\n"), msg, date, time);
         }
 
         wchar_t buffer[32 * 1024];
@@ -1830,6 +1825,18 @@ namespace winrt::Microsoft::Terminal::Control::implementation
             }
 
             _terminal->Write(message);
+
+            // Show 3 lines of scrollback to the user, so they know it's there. Otherwise, in particular with the well
+            // hidden touch scrollbars in WinUI 2 and later, there's no indication that there's something to scroll up to.
+            //
+            // We only show 3 lines because ConPTY doesn't know about our restored buffer contents initially,
+            // and so ReadConsole calls will return whitespace.
+            //
+            // We also avoid using actual newlines or similar here, because if we ever change our text buffer implementation
+            // to actually track the written contents, we don't want this to be part of the next buffer snapshot.
+            const auto cursorPosition = _terminal->GetCursorPosition();
+            const auto y = std::max(0, cursorPosition.y - 4);
+            _terminal->SetViewportPosition({ 0, y });
         }
     }