Fix the issue where the candidate window cannot be pulled up when switching back from Microsoft's emoji panel, and deeply optimize the stability of IPC connections.

src/Thread/ThreadFocusSink.cpp

@@ -2,8 +2,57 @@
 #include "Private.h"
 #include "MetasequoiaIME.h"
 #include "CandidateListUIPresenter.h"
-#include <debugapi.h>
-#include "fmt/xchar.h"
+#include <debugapi.h>
+#include <cwchar>
+#include "fmt/xchar.h"
+
+namespace
+{
+bool IsWindowsTextInputHostWindow(HWND window)
+{
+    if (!window)
+    {
+        return false;
+    }
+
+    DWORD processId = 0;
+    GetWindowThreadProcessId(window, &processId);
+    if (processId == 0)
+    {
+        return false;
+    }
+
+    HANDLE process = OpenProcess(PROCESS_QUERY_LIMITED_INFORMATION, FALSE,
+                                 processId);
+    if (!process)
+    {
+        return false;
+    }
+
+    WCHAR imagePath[32768] = {};
+    DWORD imagePathLength = ARRAYSIZE(imagePath);
+    const bool queried =
+        QueryFullProcessImageNameW(process, 0, imagePath, &imagePathLength) !=
+        FALSE;
+    CloseHandle(process);
+    if (!queried || imagePathLength == 0)
+    {
+        return false;
+    }
+
+    const WCHAR *fileName = wcsrchr(imagePath, L'\\');
+    fileName = fileName ? fileName + 1 : imagePath;
+    return _wcsicmp(fileName, L"TextInputHost.exe") == 0;
+}
+} // namespace
+
+bool CMetasequoiaIME::_CaptureWindowsTextInputHostFocusLoss()
+{
+    _focusLostToWindowsTextInputHost =
+        _focusLostToWindowsTextInputHost ||
+        IsWindowsTextInputHostWindow(GetForegroundWindow());
+    return _focusLostToWindowsTextInputHost;
+}
 
 //+---------------------------------------------------------------------------
 //
@@ -13,7 +62,19 @@
 
 STDAPI CMetasequoiaIME::OnSetThreadFocus()
 {
-    PostMessage(_msgWndHandle, WM_ThreadFocus, 0, 0);
+    if (!IsNamedpipeFocusStateOwner(this))
+    {
+        return S_OK;
+    }
+    // Do not consume this marker here. TextInputHost owns a separate TSF
+    // client, so the authoritative document OnSetFocus must use it to force a
+    // new Server activation even when our local pipe handles still look live.
+    // Match bcaf34e: thread focus is observational. Document OnSetFocus owns
+    // disconnect/reconnect; this callback only refreshes status/presenter.
+    if (_msgWndHandle && IsWindow(_msgWndHandle))
+    {
+        PostMessage(_msgWndHandle, WM_ThreadFocus, 0, 0);
+    }
     if (_pCandidateListUIPresenter)
     {
         ITfDocumentMgr *pCandidateListDocumentMgr = nullptr;
@@ -26,11 +87,11 @@ STDAPI CMetasequoiaIME::OnSetThreadFocus()
                 _pCandidateListUIPresenter->OnSetThreadFocus();
             }
 
-            pCandidateListDocumentMgr->Release();
-        }
-    }
-    return S_OK;
-}
+            pCandidateListDocumentMgr->Release();
+        }
+    }
+    return S_OK;
+}
 
 //+---------------------------------------------------------------------------
 //
@@ -40,28 +101,42 @@ STDAPI CMetasequoiaIME::OnSetThreadFocus()
 
 STDAPI CMetasequoiaIME::OnKillThreadFocus()
 {
+    if (!IsNamedpipeFocusStateOwner(this) || !Global::g_connected)
+    {
+        return S_OK;
+    }
+    _focusLostToWindowsTextInputHost = false;
+    (void)_CaptureWindowsTextInputHostFocusLoss();
+
+    // ITfThreadFocusSink reports temporary auxiliary UI transitions as well
+    // as real application focus changes. The known-good implementation did
+    // not use this callback as an IPC/session boundary: document/top-context
+    // changes are already handled by ITfThreadMgrEventSink, and TIP switching
+    // is handled by Deactivate. Keep the current composition and pipe epoch
+    // intact here, especially for TextInputHost.exe / Win+..
     if (_pCandidateListUIPresenter)
     {
         ITfDocumentMgr *pCandidateListDocumentMgr = nullptr;
         ITfContext *pTfContext = _pCandidateListUIPresenter->_GetContextDocument();
 
-        if ((nullptr != pTfContext) && SUCCEEDED(pTfContext->GetDocumentMgr(&pCandidateListDocumentMgr)))
-        {
+        if ((nullptr != pTfContext) && SUCCEEDED(pTfContext->GetDocumentMgr(&pCandidateListDocumentMgr)))
+        {
             if (_pDocMgrLastFocused)
             {
                 _pDocMgrLastFocused->Release();
                 _pDocMgrLastFocused = nullptr;
-            }
-            _pDocMgrLastFocused = pCandidateListDocumentMgr;
-            if (_pDocMgrLastFocused)
-            {
-                _pDocMgrLastFocused->AddRef();
-            }
-        }
-        _pCandidateListUIPresenter->OnKillThreadFocus();
-    }
-    return S_OK;
-}
+            }
+            // GetDocumentMgr already returned one owned reference. Transfer it
+            // directly to _pDocMgrLastFocused; adding another reference here
+            // leaks one on every Win+. / thread-focus round trip.
+            _pDocMgrLastFocused = pCandidateListDocumentMgr;
+            pCandidateListDocumentMgr = nullptr;
+
+        }
+        _pCandidateListUIPresenter->OnKillThreadFocus();
+    }
+    return S_OK;
+}
 
 BOOL CMetasequoiaIME::_InitThreadFocusSink()
 {