diff --git a/RimeWithWeasel/RimeWithWeasel.cpp b/RimeWithWeasel/RimeWithWeasel.cpp
index c4d3a5e22c..709cd7ee86 100644
--- a/RimeWithWeasel/RimeWithWeasel.cpp
+++ b/RimeWithWeasel/RimeWithWeasel.cpp
@@ -500,6 +500,9 @@ void RimeWithWeaselHandler::SetOption(WeaselSessionId ipc_id,
   } else {
     rime_api->set_option(to_session_id(ipc_id), opt.c_str(), val);
   }
+  // refresh UI (and tray icon) so the option change takes effect immediately,
+  // e.g. when toggling ascii_mode from the TSF language bar
+  _UpdateUI(ipc_id ? ipc_id : m_active_session);
 }
 
 void RimeWithWeaselHandler::OnUpdateUI(std::function<void()> const& cb) {
diff --git a/WeaselIPCServer/WeaselServerImpl.cpp b/WeaselIPCServer/WeaselServerImpl.cpp
index 1131e41e7e..0c276442ff 100644
--- a/WeaselIPCServer/WeaselServerImpl.cpp
+++ b/WeaselIPCServer/WeaselServerImpl.cpp
@@ -131,6 +131,19 @@ LRESULT ServerImpl::OnCommand(UINT uMsg,
   return 0;
 }
 
+LRESULT ServerImpl::OnServiceNotifyMessage(UINT uMsg,
+                                           WPARAM wParam,
+                                           LPARAM lParam,
+                                           BOOL& bHandled) {
+  // Runs on the server message thread, NOT on a pipe worker thread and
+  // without holding g_api_mutex, so that Shell_NotifyIcon inside the tray
+  // update can never deadlock against the taskbar UI thread.
+  if (m_trayRefreshCallback) {
+    m_trayRefreshCallback();
+  }
+  return 0;
+}
+
 DWORD ServerImpl::OnCommand(WEASEL_IPC_COMMAND uMsg,
                             DWORD wParam,
                             DWORD lParam) {
@@ -466,6 +479,10 @@ void Server::AddMenuHandler(UINT uID, CommandHandler handler) {
   m_pImpl->AddMenuHandler(uID, handler);
 }
 
+void Server::SetTrayRefreshCallback(std::function<void()> callback) {
+  m_pImpl->SetTrayRefreshCallback(callback);
+}
+
 HWND Server::GetHWnd() {
   return m_pImpl->m_hWnd;
 }
diff --git a/WeaselIPCServer/WeaselServerImpl.h b/WeaselIPCServer/WeaselServerImpl.h
index 5a2e3ab078..e826d066dc 100644
--- a/WeaselIPCServer/WeaselServerImpl.h
+++ b/WeaselIPCServer/WeaselServerImpl.h
@@ -28,6 +28,7 @@ class ServerImpl : public CWindowImpl<ServerImpl, CWindow, ServerWinTraits>
   MESSAGE_HANDLER(WM_DWMCOLORIZATIONCOLORCHANGED, OnColorChange)
   MESSAGE_HANDLER(WM_SETTINGCHANGE, OnColorChange)
   MESSAGE_HANDLER(WM_COMMAND, OnCommand)
+  MESSAGE_HANDLER(WM_WEASEL_SERVICE_NOTIFY, OnServiceNotifyMessage)
   END_MSG_MAP()
 
   LRESULT OnColorChange(UINT uMsg,
@@ -46,6 +47,10 @@ class ServerImpl : public CWindowImpl<ServerImpl, CWindow, ServerWinTraits>
                              LPARAM lParam,
                              BOOL& bHandled);
   LRESULT OnCommand(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled);
+  LRESULT OnServiceNotifyMessage(UINT uMsg,
+                                 WPARAM wParam,
+                                 LPARAM lParam,
+                                 BOOL& bHandled);
   DWORD OnCommand(WEASEL_IPC_COMMAND uMsg, DWORD wParam, DWORD lParam);
   DWORD OnEcho(WEASEL_IPC_COMMAND uMsg, DWORD wParam, DWORD lParam);
   DWORD OnStartSession(WEASEL_IPC_COMMAND uMsg, DWORD wParam, DWORD lParam);
@@ -85,6 +90,9 @@ class ServerImpl : public CWindowImpl<ServerImpl, CWindow, ServerWinTraits>
   void AddMenuHandler(UINT uID, CommandHandler& handler) {
     m_MenuHandlers[uID] = handler;
   }
+  void SetTrayRefreshCallback(std::function<void()> callback) {
+    m_trayRefreshCallback = callback;
+  }
 
  private:
   void _Finailize();
@@ -95,6 +103,7 @@ class ServerImpl : public CWindowImpl<ServerImpl, CWindow, ServerWinTraits>
   std::unique_ptr<boost::thread> pipeThread;
   RequestHandler* m_pRequestHandler;  // reference
   std::map<UINT, CommandHandler> m_MenuHandlers;
+  std::function<void()> m_trayRefreshCallback;
   HMODULE m_hUser32Module;
   SecurityAttribute sa;
   BOOL m_darkMode;
diff --git a/WeaselServer/WeaselServerApp.cpp b/WeaselServer/WeaselServerApp.cpp
index e09c4c5ed2..6696b98e02 100644
--- a/WeaselServer/WeaselServerApp.cpp
+++ b/WeaselServer/WeaselServerApp.cpp
@@ -30,13 +30,15 @@ int WeaselServerApp::Run() {
   m_ui.Create(m_server.GetHWnd());
 
   m_handler->Initialize();
-  m_handler->OnUpdateUI([this]() { tray_icon.Refresh(); });
+  m_handler->OnUpdateUI([this]() { tray_icon.RequestRefresh(); });
 
   tray_icon.Create(m_server.GetHWnd());
-  tray_icon.Refresh();
+  m_server.SetTrayRefreshCallback([this]() { tray_icon.ApplyRefresh(); });
+  tray_icon.RequestRefresh();
 
   int ret = m_server.Run();
 
+  tray_icon.DisableRefresh();
   m_handler->Finalize();
   m_ui.Destroy();
   tray_icon.RemoveIcon();
diff --git a/WeaselServer/WeaselTrayIcon.cpp b/WeaselServer/WeaselTrayIcon.cpp
index 119111affd..3eaff9b30a 100644
--- a/WeaselServer/WeaselTrayIcon.cpp
+++ b/WeaselServer/WeaselTrayIcon.cpp
@@ -37,9 +37,50 @@ BOOL WeaselTrayIcon::Create(HWND hTargetWnd) {
   return bRet;
 }
 
-void WeaselTrayIcon::Refresh() {
-  if (!m_style.display_tray_icon &&
-      !m_status.disabled)  // display notification when deploying
+void WeaselTrayIcon::RequestRefresh() {
+  std::lock_guard<std::mutex> lock(m_state_mutex);
+  if (!m_refresh_enabled) {
+    return;
+  }
+  m_pending_state = WeaselTrayIconState::From(m_style, m_status);
+  if (m_refresh_pending) {
+    return;
+  }
+  m_refresh_pending = true;
+  if (!::PostMessage(GetTargetWnd(), WM_WEASEL_SERVICE_NOTIFY, 0, 0)) {
+    m_refresh_pending = false;
+  }
+}
+
+void WeaselTrayIcon::ApplyRefresh() {
+  WeaselTrayIconState state;
+  {
+    std::lock_guard<std::mutex> lock(m_state_mutex);
+    if (!m_refresh_pending || !m_refresh_enabled) {
+      return;
+    }
+    state = m_pending_state;
+    m_refresh_pending = false;
+    m_refresh_in_progress = true;
+  }
+  Refresh(state);
+  {
+    std::lock_guard<std::mutex> lock(m_state_mutex);
+    m_refresh_in_progress = false;
+  }
+  m_state_cv.notify_all();
+}
+
+void WeaselTrayIcon::DisableRefresh() {
+  std::unique_lock<std::mutex> lock(m_state_mutex);
+  m_refresh_enabled = false;
+  m_refresh_pending = false;
+  m_state_cv.wait(lock, [this] { return !m_refresh_in_progress; });
+}
+
+void WeaselTrayIcon::Refresh(const WeaselTrayIconState& state) {
+  if (!state.display_tray_icon &&
+      !state.disabled)  // display notification when deploying
   {
     if (m_mode != INITIAL) {
       RemoveIcon();
@@ -48,24 +89,24 @@ void WeaselTrayIcon::Refresh() {
     m_disabled = false;
     return;
   }
-  WeaselTrayMode mode = m_status.disabled     ? DISABLED
-                        : m_status.ascii_mode ? ASCII
-                                              : ZHUNG;
+  WeaselTrayMode mode = state.disabled     ? DISABLED
+                        : state.ascii_mode ? ASCII
+                                           : ZHUNG;
   /* change icon, when
           1,mode changed
           2,icon changed
-          3,both m_schema_zhung_icon and m_style.current_zhung_icon empty(for
-     initialize) 4,both m_schema_ascii_icon and m_style.current_ascii_icon
+          3,both m_schema_zhung_icon and state.current_zhung_icon empty(for
+     initialize) 4,both m_schema_ascii_icon and state.current_ascii_icon
      empty(for initialize)
   */
-  if (mode != m_mode || m_schema_zhung_icon != m_style.current_zhung_icon ||
-      (m_schema_zhung_icon.empty() && m_style.current_zhung_icon.empty()) ||
-      m_schema_ascii_icon != m_style.current_ascii_icon ||
-      (m_schema_ascii_icon.empty() && m_style.current_ascii_icon.empty())) {
+  if (mode != m_mode || m_schema_zhung_icon != state.current_zhung_icon ||
+      (m_schema_zhung_icon.empty() && state.current_zhung_icon.empty()) ||
+      m_schema_ascii_icon != state.current_ascii_icon ||
+      (m_schema_ascii_icon.empty() && state.current_ascii_icon.empty())) {
     ShowIcon();
     m_mode = mode;
-    m_schema_zhung_icon = m_style.current_zhung_icon;
-    m_schema_ascii_icon = m_style.current_ascii_icon;
+    m_schema_zhung_icon = state.current_zhung_icon;
+    m_schema_ascii_icon = state.current_ascii_icon;
     if (mode == ASCII) {
       if (m_schema_ascii_icon.empty())
         SetIcon(mode_icon[mode]);
diff --git a/WeaselServer/WeaselTrayIcon.h b/WeaselServer/WeaselTrayIcon.h
index 42d407aaa5..5afa715831 100644
--- a/WeaselServer/WeaselTrayIcon.h
+++ b/WeaselServer/WeaselTrayIcon.h
@@ -3,8 +3,54 @@
 #include <WeaselIPC.h>
 #include "SystemTraySDK.h"
 
+#include <condition_variable>
+#include <mutex>
+
 #define WM_WEASEL_TRAY_NOTIFY (WEASEL_IPC_LAST_COMMAND + 100)
 
+// Snapshot of the tray-relevant UI state, computed on the pipe worker thread
+// and applied on the server message thread. Keeps Shell_NotifyIcon off the
+// pipe worker threads (and away from g_api_mutex), avoiding the deadlock loop
+// where the taskbar UI thread waits on the pipe while the server waits for the
+// taskbar UI thread inside Shell_NotifyIcon.
+struct WeaselTrayIconState {
+  WeaselTrayIconState()
+      : valid(false),
+        display_tray_icon(false),
+        disabled(false),
+        ascii_mode(false) {}
+
+  static WeaselTrayIconState From(const weasel::UIStyle& style,
+                                  const weasel::Status& status) {
+    WeaselTrayIconState state;
+    state.valid = true;
+    state.display_tray_icon = style.display_tray_icon;
+    state.disabled = status.disabled;
+    state.ascii_mode = status.ascii_mode;
+    state.current_zhung_icon = style.current_zhung_icon;
+    state.current_ascii_icon = style.current_ascii_icon;
+    return state;
+  }
+
+  bool operator==(const WeaselTrayIconState& rhs) const {
+    return valid == rhs.valid && display_tray_icon == rhs.display_tray_icon &&
+           disabled == rhs.disabled && ascii_mode == rhs.ascii_mode &&
+           current_zhung_icon == rhs.current_zhung_icon &&
+           current_ascii_icon == rhs.current_ascii_icon;
+  }
+
+  bool operator!=(const WeaselTrayIconState& rhs) const {
+    return !(*this == rhs);
+  }
+
+  bool valid;
+  bool display_tray_icon;
+  bool disabled;
+  bool ascii_mode;
+  std::wstring current_zhung_icon;
+  std::wstring current_ascii_icon;
+};
+
 class WeaselTrayIcon : public CSystemTray {
  public:
   enum WeaselTrayMode {
@@ -17,15 +63,32 @@ class WeaselTrayIcon : public CSystemTray {
   WeaselTrayIcon(weasel::UI& ui);
 
   BOOL Create(HWND hTargetWnd);
-  void Refresh();
+
+  // Captures the tray-relevant state and posts a refresh request to the server
+  // message thread. Never calls Shell_NotifyIcon itself.
+  void RequestRefresh();
+  void DisableRefresh();
+
+  // Runs on the server message thread (no g_api_mutex held).
+  void ApplyRefresh();
 
  protected:
   virtual void CustomizeMenu(HMENU hMenu);
 
+  void Refresh(const WeaselTrayIconState& state);
+
   weasel::UIStyle& m_style;
   weasel::Status& m_status;
   WeaselTrayMode m_mode;
   std::wstring m_schema_zhung_icon;
   std::wstring m_schema_ascii_icon;
   bool m_disabled;
+
+  // Guarded by m_state_mutex.
+  bool m_refresh_enabled = true;
+  bool m_refresh_pending = false;
+  bool m_refresh_in_progress = false;
+  WeaselTrayIconState m_pending_state;
+  std::mutex m_state_mutex;
+  std::condition_variable m_state_cv;
 };
diff --git a/include/WeaselIPC.h b/include/WeaselIPC.h
index d260ac2b7d..27bfd63687 100644
--- a/include/WeaselIPC.h
+++ b/include/WeaselIPC.h
@@ -35,6 +35,10 @@ enum WEASEL_IPC_COMMAND {
   WEASEL_IPC_LAST_COMMAND
 };
 
+// Posted by WeaselTrayIcon to the server window so that Shell_NotifyIcon runs
+// on the server message thread instead of a pipe worker thread.
+#define WM_WEASEL_SERVICE_NOTIFY (WEASEL_IPC_LAST_COMMAND + 200)
+
 namespace weasel {
 struct PipeMessage {
   WEASEL_IPC_COMMAND Msg;
@@ -163,6 +167,10 @@ class Server {
   void AddMenuHandler(UINT uID, CommandHandler handler);
   HWND GetHWnd();
 
+  // Callback invoked on the server message thread when a tray icon refresh is
+  // requested from a pipe worker thread.
+  void SetTrayRefreshCallback(std::function<void()> callback);
+
  private:
   ServerImpl* m_pImpl;
 };