This state of the world works.

src/cascadia/TerminalApp/TerminalPage.cpp

@@ -2430,11 +2430,11 @@ namespace winrt::TerminalApp::implementation
         // TermControl will copy the settings out of the settings passed to it.
         TermControl term{ settings.DefaultSettings(), settings.UnfocusedSettings(), connection };
 
-        // // GH#12515: ConPTY assumes it's hidden at the start. If we're not, let it know now.
-        // if (_visible)
-        // {
-        //     term.WindowVisibilityChanged(_visible);
-        // }
+        // GH#12515: ConPTY assumes it's hidden at the start. If we're not, let it know now.
+        if (_visible)
+        {
+            term.WindowVisibilityChanged(_visible);
+        }
 
         if (_hostingHwnd.has_value())
         {

src/cascadia/TerminalConnection/ConptyConnection.cpp

@@ -317,10 +317,10 @@ namespace winrt::Microsoft::Terminal::TerminalConnection::implementation
             }
 
             // GH#12515: The conpty assumes it's hidden at the start. If we're visible, let it know now.
-            // if (_initialVisibility)
-            // {
-            //     THROW_IF_FAILED(ConptyShowHidePseudoConsole(_hPC.get(), _initialVisibility));
-            // }
+            if (_initialVisibility)
+            {
+                THROW_IF_FAILED(ConptyShowHidePseudoConsole(_hPC.get(), _initialVisibility));
+            }
             // THROW_IF_FAILED(ConptyShowHidePseudoConsole(_hPC.get(), _initialVisibility));
 
             THROW_IF_FAILED(_LaunchAttachedClient());

src/cascadia/TerminalControl/ControlCore.cpp

@@ -1706,10 +1706,13 @@ namespace winrt::Microsoft::Terminal::Control::implementation
     // - <none>
     void ControlCore::WindowVisibilityChanged(const bool showOrHide)
     {
-        // show is true, hide is false
-        if (auto conpty{ _connection.try_as<TerminalConnection::ConptyConnection>() })
+        if (_initializedTerminal)
         {
-            conpty.ShowHide(showOrHide);
+            // show is true, hide is false
+            if (auto conpty{ _connection.try_as<TerminalConnection::ConptyConnection>() })
+            {
+                conpty.ShowHide(showOrHide);
+            }
         }
     }
 

src/host/PtySignalInputThread.cpp

@@ -74,12 +74,19 @@ void PtySignalInputThread::ConnectConsole() noexcept
     {
         _DoShowHide(_initialShowHide->show);
     }
+}
 
-    // If we were given a owner HWND, then manually start the pseudo window now.
-    if (_earlyReparent)
-    {
-        _DoSetWindowParent(*_earlyReparent);
-    }
+// Method Description:
+// - Create our pseudowindow. We're doing this here, instead of in
+//   ConnectConsole, because the window is created in
+//   ConsoleInputThreadProcWin32, before ConnectConsole is first called. Doing
+//   this here ensures that the window is first created with the initial owner
+//   set up (if so specified).
+// - Refer to GH#13066 for details.
+void PtySignalInputThread::CreatePseudoWindow()
+{
+    HWND owner = _earlyReparent.has_value() ? reinterpret_cast<HWND>((*_earlyReparent).handle) : HWND_DESKTOP;
+    ServiceLocator::LocatePseudoWindow(owner);
 }
 
 // Method Description:

src/host/PtySignalInputThread.hpp

@@ -33,6 +33,7 @@ namespace Microsoft::Console
         PtySignalInputThread& operator=(const PtySignalInputThread&) = delete;
 
         void ConnectConsole() noexcept;
+        void CreatePseudoWindow();
 
     private:
         enum class PtySignal : unsigned short

src/host/VtIo.cpp

@@ -300,18 +300,34 @@ bool VtIo::IsUsingVt() const
 
     if (_pPtySignalInputThread)
     {
-        // IMPORTANT! Start the pseudo window on this thread. This thread has a
-        // message pump. If you DON'T, then a DPI change in the owning hwnd will
-        // cause us to get a dpi change as well, which we'll never deque and
-        // handle, effectively HANGING THE OWNER HWND.
+        // Let the signal thread know that the console is connected.
         //
-        // Let the signal thread know that the console is connected
+        // By this point, the pseudo window should have already been created, by
+        // ConsoleInputThreadProcWin32. That thread has a message pump, which is
+        // needed to ensure that DPI change messages to the owning terminal
+        // window don't end up hanging because the pty didn't also process it.
         _pPtySignalInputThread->ConnectConsole();
     }
 
     return S_OK;
 }
 
+// Method Description:
+// - Create our pseudowindow. This is exclusively called by
+//   ConsoleInputThreadProcWin32 on the console input thread.
+//    * It needs to be called on that thread, before any other calls to
+//      LocatePseudoWindow, to make sure that the input thread is the HWND's
+//      message thread.
+//    * It needs to be plumbed through the signal thread, because the signal
+//      thread knows if someone should be marked as the window's owner. It's
+//      VERY IMPORTANT that any initial owners are set up when the window is
+//      first created.
+// - Refer to GH#13066 for details.
+void VtIo::CreatePseudoWindow()
+{
+    _pPtySignalInputThread->CreatePseudoWindow();
+}
+
 // Method Description:
 // - Create and start the signal thread. The signal thread can be created
 //      independent of the i/o threads, and doesn't require a client first

src/host/VtIo.hpp

@@ -52,6 +52,8 @@ namespace Microsoft::Console::VirtualTerminal
 
         [[nodiscard]] HRESULT ManuallyClearScrollback() const noexcept;
 
+        void CreatePseudoWindow();
+
     private:
         // After CreateIoHandlers is called, these will be invalid.
         wil::unique_hfile _hInput;

src/interactivity/win32/windowio.cpp

@@ -1036,9 +1036,18 @@ DWORD WINAPI ConsoleInputThreadProcWin32(LPVOID /*lpParameter*/)
         // If we are headless (because we're a pseudo console), we
         // will still need a window handle in the win32 environment
         // in case anyone sends messages at that HWND (vim.exe is an example.)
-        // We have to CreateWindow on the same thread that will pump the messages
-        // which is this thread.
-        ServiceLocator::LocatePseudoWindow();
+        //
+        // IMPORTANT! We have to CreateWindow on the same thread that will pump
+        // the messages, which is this thread. If you DON'T, then a DPI change
+        // in the owning hwnd will cause us to get a dpi change as well, which
+        // we'll never deque and handle, effectively HANGING THE OWNER HWND.
+        // ServiceLocator::LocatePseudoWindow();
+        //
+        // Instead of just calling LocatePseudoWindow, make sure to go through
+        // VtIo's CreatePseudoWindow, which will make sure that the window is
+        // successfully created with the owner configured when the window is
+        // first created. See GH#13066 for details.
+        ServiceLocator::LocateGlobals().getConsoleInformation().GetVtIo()->CreatePseudoWindow();
     }
 
     UnlockConsole();