diff --git a/openless-all/app/windows-ime/OpenLessIme.vcxproj b/openless-all/app/windows-ime/OpenLessIme.vcxproj
index 32c1ba4f..af417141 100644
--- a/openless-all/app/windows-ime/OpenLessIme.vcxproj
+++ b/openless-all/app/windows-ime/OpenLessIme.vcxproj
@@ -77,6 +77,7 @@
     <ClCompile Include="src\class_factory.cpp" />
     <ClCompile Include="src\dllmain.cpp" />
     <ClCompile Include="src\edit_session.cpp" />
+    <ClCompile Include="src\ipc_client.cpp" />
     <ClCompile Include="src\registry.cpp" />
     <ClCompile Include="src\text_service.cpp" />
   </ItemGroup>
@@ -84,6 +85,7 @@
     <ClInclude Include="src\class_factory.h" />
     <ClInclude Include="src\edit_session.h" />
     <ClInclude Include="src\guids.h" />
+    <ClInclude Include="src\ipc_client.h" />
     <ClInclude Include="src\registry.h" />
     <ClInclude Include="src\text_service.h" />
   </ItemGroup>
diff --git a/openless-all/app/windows-ime/src/ipc_client.cpp b/openless-all/app/windows-ime/src/ipc_client.cpp
new file mode 100644
index 00000000..d34b528e
--- /dev/null
+++ b/openless-all/app/windows-ime/src/ipc_client.cpp
@@ -0,0 +1,486 @@
+#include "ipc_client.h"
+
+#include <cstdint>
+#include <string>
+
+#include "text_service.h"
+
+namespace {
+
+constexpr wchar_t kPipeName[] = L"\\\\.\\pipe\\OpenLessImeSubmit";
+constexpr DWORD kPipeBufferSize = 4096;
+constexpr size_t kMaxJsonLineBytes = 64 * 1024;
+
+struct SubmitMessage {
+  std::wstring type;
+  std::wstring session_id;
+  std::wstring text;
+  int protocol_version = 0;
+  bool has_type = false;
+  bool has_session_id = false;
+  bool has_text = false;
+  bool has_protocol_version = false;
+};
+
+bool AppendUtf8AsWide(const char* data,
+                      int length,
+                      std::wstring* output) {
+  if (length == 0) {
+    return true;
+  }
+
+  const int required = MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, data,
+                                           length, nullptr, 0);
+  if (required <= 0) {
+    return false;
+  }
+
+  const size_t old_size = output->size();
+  output->resize(old_size + static_cast<size_t>(required));
+  return MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, data, length,
+                             output->data() + old_size, required) == required;
+}
+
+bool WideToUtf8(const std::wstring& value, std::string* output) {
+  output->clear();
+  if (value.empty()) {
+    return true;
+  }
+
+  const int required = WideCharToMultiByte(CP_UTF8, WC_ERR_INVALID_CHARS,
+                                           value.c_str(),
+                                           static_cast<int>(value.size()),
+                                           nullptr, 0, nullptr, nullptr);
+  if (required <= 0) {
+    return false;
+  }
+
+  output->resize(static_cast<size_t>(required));
+  return WideCharToMultiByte(CP_UTF8, WC_ERR_INVALID_CHARS, value.c_str(),
+                             static_cast<int>(value.size()), output->data(),
+                             required, nullptr, nullptr) == required;
+}
+
+void SkipWhitespace(const std::string& json, size_t* pos) {
+  while (*pos < json.size()) {
+    const char c = json[*pos];
+    if (c != ' ' && c != '\t' && c != '\r' && c != '\n') {
+      return;
+    }
+    ++(*pos);
+  }
+}
+
+int HexDigit(char c) {
+  if (c >= '0' && c <= '9') {
+    return c - '0';
+  }
+  if (c >= 'a' && c <= 'f') {
+    return c - 'a' + 10;
+  }
+  if (c >= 'A' && c <= 'F') {
+    return c - 'A' + 10;
+  }
+  return -1;
+}
+
+bool ParseJsonString(const std::string& json,
+                     size_t* pos,
+                     std::wstring* value) {
+  value->clear();
+  if (*pos >= json.size() || json[*pos] != '"') {
+    return false;
+  }
+  ++(*pos);
+
+  size_t segment_start = *pos;
+  while (*pos < json.size()) {
+    const char c = json[*pos];
+    if (static_cast<unsigned char>(c) < 0x20) {
+      return false;
+    }
+
+    if (c == '"') {
+      if (!AppendUtf8AsWide(json.data() + segment_start,
+                            static_cast<int>(*pos - segment_start), value)) {
+        return false;
+      }
+      ++(*pos);
+      return true;
+    }
+
+    if (c != '\\') {
+      ++(*pos);
+      continue;
+    }
+
+    if (!AppendUtf8AsWide(json.data() + segment_start,
+                          static_cast<int>(*pos - segment_start), value)) {
+      return false;
+    }
+
+    ++(*pos);
+    if (*pos >= json.size()) {
+      return false;
+    }
+
+    const char escaped = json[*pos];
+    switch (escaped) {
+      case '"':
+      case '\\':
+      case '/':
+        value->push_back(static_cast<wchar_t>(escaped));
+        ++(*pos);
+        break;
+      case 'b':
+        value->push_back(L'\b');
+        ++(*pos);
+        break;
+      case 'f':
+        value->push_back(L'\f');
+        ++(*pos);
+        break;
+      case 'n':
+        value->push_back(L'\n');
+        ++(*pos);
+        break;
+      case 'r':
+        value->push_back(L'\r');
+        ++(*pos);
+        break;
+      case 't':
+        value->push_back(L'\t');
+        ++(*pos);
+        break;
+      case 'u': {
+        if (*pos + 4 >= json.size()) {
+          return false;
+        }
+        uint32_t code_unit = 0;
+        for (int i = 1; i <= 4; ++i) {
+          const int digit = HexDigit(json[*pos + static_cast<size_t>(i)]);
+          if (digit < 0) {
+            return false;
+          }
+          code_unit = (code_unit << 4) | static_cast<uint32_t>(digit);
+        }
+        value->push_back(static_cast<wchar_t>(code_unit));
+        *pos += 5;
+        break;
+      }
+      default:
+        return false;
+    }
+
+    segment_start = *pos;
+  }
+
+  return false;
+}
+
+bool ParseJsonInteger(const std::string& json, size_t* pos, int* value) {
+  if (*pos >= json.size() || json[*pos] < '0' || json[*pos] > '9') {
+    return false;
+  }
+
+  int parsed = 0;
+  while (*pos < json.size() && json[*pos] >= '0' && json[*pos] <= '9') {
+    parsed = parsed * 10 + (json[*pos] - '0');
+    ++(*pos);
+  }
+
+  *value = parsed;
+  return true;
+}
+
+bool SkipJsonValue(const std::string& json, size_t* pos) {
+  std::wstring ignored;
+  if (*pos >= json.size()) {
+    return false;
+  }
+  if (json[*pos] == '"') {
+    return ParseJsonString(json, pos, &ignored);
+  }
+  while (*pos < json.size() && json[*pos] != ',' && json[*pos] != '}') {
+    ++(*pos);
+  }
+  return true;
+}
+
+bool ParseSubmitMessage(const std::string& json, SubmitMessage* message) {
+  size_t pos = 0;
+  SkipWhitespace(json, &pos);
+  if (pos >= json.size() || json[pos] != '{') {
+    return false;
+  }
+  ++pos;
+
+  while (true) {
+    SkipWhitespace(json, &pos);
+    if (pos < json.size() && json[pos] == '}') {
+      ++pos;
+      break;
+    }
+
+    std::wstring key;
+    if (!ParseJsonString(json, &pos, &key)) {
+      return false;
+    }
+
+    SkipWhitespace(json, &pos);
+    if (pos >= json.size() || json[pos] != ':') {
+      return false;
+    }
+    ++pos;
+    SkipWhitespace(json, &pos);
+
+    if (key == L"type") {
+      message->has_type = ParseJsonString(json, &pos, &message->type);
+      if (!message->has_type) {
+        return false;
+      }
+    } else if (key == L"sessionId") {
+      message->has_session_id =
+          ParseJsonString(json, &pos, &message->session_id);
+      if (!message->has_session_id) {
+        return false;
+      }
+    } else if (key == L"text") {
+      message->has_text = ParseJsonString(json, &pos, &message->text);
+      if (!message->has_text) {
+        return false;
+      }
+    } else if (key == L"protocolVersion") {
+      message->has_protocol_version =
+          ParseJsonInteger(json, &pos, &message->protocol_version);
+      if (!message->has_protocol_version) {
+        return false;
+      }
+    } else if (!SkipJsonValue(json, &pos)) {
+      return false;
+    }
+
+    SkipWhitespace(json, &pos);
+    if (pos < json.size() && json[pos] == ',') {
+      ++pos;
+      continue;
+    }
+    if (pos < json.size() && json[pos] == '}') {
+      ++pos;
+      break;
+    }
+    return false;
+  }
+
+  SkipWhitespace(json, &pos);
+  return pos == json.size();
+}
+
+std::wstring EscapeJsonString(const std::wstring& value) {
+  std::wstring escaped;
+  for (wchar_t ch : value) {
+    switch (ch) {
+      case L'"':
+        escaped += L"\\\"";
+        break;
+      case L'\\':
+        escaped += L"\\\\";
+        break;
+      case L'\b':
+        escaped += L"\\b";
+        break;
+      case L'\f':
+        escaped += L"\\f";
+        break;
+      case L'\n':
+        escaped += L"\\n";
+        break;
+      case L'\r':
+        escaped += L"\\r";
+        break;
+      case L'\t':
+        escaped += L"\\t";
+        break;
+      default:
+        if (ch < 0x20) {
+          wchar_t buffer[7] = {};
+          swprintf_s(buffer, L"\\u%04X", static_cast<unsigned int>(ch));
+          escaped += buffer;
+        } else {
+          escaped.push_back(ch);
+        }
+        break;
+    }
+  }
+  return escaped;
+}
+
+}  // namespace
+
+OpenLessPipeServer::OpenLessPipeServer() = default;
+
+OpenLessPipeServer::~OpenLessPipeServer() {
+  Stop();
+}
+
+void OpenLessPipeServer::Start(OpenLessTextService* service) {
+  if (service == nullptr || thread_.joinable()) {
+    return;
+  }
+
+  stop_requested_.store(false);
+  service_ = service;
+  service_->AddRef();
+  thread_ = std::thread(&OpenLessPipeServer::Run, this);
+}
+
+void OpenLessPipeServer::Stop() {
+  stop_requested_.store(true);
+  if (thread_.joinable()) {
+    CancelSynchronousIo(thread_.native_handle());
+    WakePipe();
+    thread_.join();
+  }
+
+  if (service_ != nullptr) {
+    service_->Release();
+    service_ = nullptr;
+  }
+}
+
+void OpenLessPipeServer::Run() {
+  while (!stop_requested_.load()) {
+    HANDLE pipe = CreateNamedPipeW(
+        kPipeName, PIPE_ACCESS_DUPLEX,
+        PIPE_TYPE_MESSAGE | PIPE_READMODE_BYTE | PIPE_WAIT, 1,
+        kPipeBufferSize, kPipeBufferSize, 0, nullptr);
+    if (pipe == INVALID_HANDLE_VALUE) {
+      return;
+    }
+
+    {
+      std::lock_guard<std::mutex> lock(pipe_mutex_);
+      pipe_handle_ = pipe;
+    }
+
+    const BOOL connected =
+        ConnectNamedPipe(pipe, nullptr)
+            ? TRUE
+            : (GetLastError() == ERROR_PIPE_CONNECTED ? TRUE : FALSE);
+
+    if (connected && !stop_requested_.load()) {
+      std::string line;
+      if (ReadJsonLine(pipe, &line)) {
+        HandleSubmitLine(pipe, line);
+      }
+    }
+
+    FlushFileBuffers(pipe);
+    DisconnectNamedPipe(pipe);
+    CloseHandle(pipe);
+
+    {
+      std::lock_guard<std::mutex> lock(pipe_mutex_);
+      if (pipe_handle_ == pipe) {
+        pipe_handle_ = INVALID_HANDLE_VALUE;
+      }
+    }
+  }
+}
+
+bool OpenLessPipeServer::ReadJsonLine(HANDLE pipe, std::string* line) {
+  line->clear();
+  char buffer[1024] = {};
+
+  while (!stop_requested_.load() && line->size() < kMaxJsonLineBytes) {
+    DWORD bytes_read = 0;
+    if (!ReadFile(pipe, buffer, sizeof(buffer), &bytes_read, nullptr)) {
+      const DWORD error = GetLastError();
+      if (error == ERROR_MORE_DATA && bytes_read > 0) {
+        line->append(buffer, buffer + bytes_read);
+        continue;
+      }
+      return !line->empty();
+    }
+
+    if (bytes_read == 0) {
+      return !line->empty();
+    }
+
+    for (DWORD i = 0; i < bytes_read; ++i) {
+      if (buffer[i] == '\n') {
+        return true;
+      }
+      line->push_back(buffer[i]);
+      if (line->size() >= kMaxJsonLineBytes) {
+        return true;
+      }
+    }
+  }
+
+  return !line->empty();
+}
+
+void OpenLessPipeServer::HandleSubmitLine(HANDLE pipe, const std::string& line) {
+  SubmitMessage message;
+  if (!ParseSubmitMessage(line, &message) || !message.has_type ||
+      !message.has_protocol_version || !message.has_session_id ||
+      !message.has_text || message.protocol_version != 1 ||
+      message.type != L"submitText") {
+    WriteResult(pipe, message.session_id, L"failed", L"protocolError");
+    return;
+  }
+
+  if (service_ == nullptr) {
+    WriteResult(pipe, message.session_id, L"failed", L"serviceUnavailable");
+    return;
+  }
+
+  const HRESULT hr =
+      service_->SubmitTextFromPipe(message.session_id, message.text);
+  if (SUCCEEDED(hr)) {
+    WriteResult(pipe, message.session_id, L"committed", nullptr);
+  } else {
+    WriteResult(pipe, message.session_id, L"rejected", L"commitRejected");
+  }
+}
+
+bool OpenLessPipeServer::WriteResult(HANDLE pipe,
+                                     const std::wstring& session_id,
+                                     const wchar_t* status,
+                                     const wchar_t* error_code) {
+  std::wstring response = L"{\"type\":\"submitResult\",\"protocolVersion\":1,";
+  response += L"\"sessionId\":\"";
+  response += EscapeJsonString(session_id);
+  response += L"\",\"status\":\"";
+  response += status;
+  response += L"\",\"errorCode\":";
+  if (error_code == nullptr) {
+    response += L"null";
+  } else {
+    response += L"\"";
+    response += error_code;
+    response += L"\"";
+  }
+  response += L"}\n";
+
+  std::string utf8_response;
+  if (!WideToUtf8(response, &utf8_response)) {
+    return false;
+  }
+
+  DWORD bytes_written = 0;
+  return WriteFile(pipe, utf8_response.data(),
+                   static_cast<DWORD>(utf8_response.size()), &bytes_written,
+                   nullptr) &&
+         bytes_written == utf8_response.size();
+}
+
+void OpenLessPipeServer::WakePipe() {
+  HANDLE pipe =
+      CreateFileW(kPipeName, GENERIC_READ | GENERIC_WRITE, 0, nullptr,
+                  OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr);
+  if (pipe != INVALID_HANDLE_VALUE) {
+    CloseHandle(pipe);
+  }
+}
diff --git a/openless-all/app/windows-ime/src/ipc_client.h b/openless-all/app/windows-ime/src/ipc_client.h
new file mode 100644
index 00000000..e0c0e799
--- /dev/null
+++ b/openless-all/app/windows-ime/src/ipc_client.h
@@ -0,0 +1,36 @@
+#pragma once
+
+#include <atomic>
+#include <mutex>
+#include <string>
+#include <thread>
+#include <windows.h>
+
+class OpenLessTextService;
+
+class OpenLessPipeServer {
+ public:
+  OpenLessPipeServer();
+  OpenLessPipeServer(const OpenLessPipeServer&) = delete;
+  OpenLessPipeServer& operator=(const OpenLessPipeServer&) = delete;
+  ~OpenLessPipeServer();
+
+  void Start(OpenLessTextService* service);
+  void Stop();
+
+ private:
+  void Run();
+  bool ReadJsonLine(HANDLE pipe, std::string* line);
+  void HandleSubmitLine(HANDLE pipe, const std::string& line);
+  bool WriteResult(HANDLE pipe,
+                   const std::wstring& session_id,
+                   const wchar_t* status,
+                   const wchar_t* error_code);
+  void WakePipe();
+
+  std::atomic<bool> stop_requested_{false};
+  std::thread thread_;
+  std::mutex pipe_mutex_;
+  HANDLE pipe_handle_ = INVALID_HANDLE_VALUE;
+  OpenLessTextService* service_ = nullptr;
+};
diff --git a/openless-all/app/windows-ime/src/text_service.cpp b/openless-all/app/windows-ime/src/text_service.cpp
index ed911832..7c4369e3 100644
--- a/openless-all/app/windows-ime/src/text_service.cpp
+++ b/openless-all/app/windows-ime/src/text_service.cpp
@@ -5,6 +5,21 @@
 #include "edit_session.h"
 
 extern LONG g_object_count;
+extern HINSTANCE g_module;
+
+namespace {
+
+constexpr wchar_t kMessageWindowClassName[] = L"OpenLessImeMessageWindow";
+constexpr UINT kSubmitTextMessage = WM_APP + 1;
+constexpr UINT kSubmitTextTimeoutMs = 3000;
+
+struct SubmitTextRequest {
+  const std::wstring* session_id = nullptr;
+  const std::wstring* text = nullptr;
+  HRESULT result = E_UNEXPECTED;
+};
+
+}  // namespace
 
 OpenLessTextService::OpenLessTextService() {
   InterlockedIncrement(&g_object_count);
@@ -59,11 +74,19 @@ STDMETHODIMP OpenLessTextService::ActivateEx(ITfThreadMgr* thread_mgr,
 
   Deactivate();
 
+  owner_thread_id_ = GetCurrentThreadId();
+
   thread_mgr_ = thread_mgr;
   thread_mgr_->AddRef();
   client_id_ = client_id;
 
-  const HRESULT hr = StartIpcServer();
+  HRESULT hr = EnsureMessageWindow();
+  if (FAILED(hr)) {
+    Deactivate();
+    return hr;
+  }
+
+  hr = StartIpcServer();
   if (FAILED(hr)) {
     Deactivate();
     return hr;
@@ -74,12 +97,14 @@ STDMETHODIMP OpenLessTextService::ActivateEx(ITfThreadMgr* thread_mgr,
 
 STDMETHODIMP OpenLessTextService::Deactivate() {
   StopIpcServer();
+  DestroyMessageWindow();
 
   if (thread_mgr_ != nullptr) {
     thread_mgr_->Release();
     thread_mgr_ = nullptr;
   }
   client_id_ = TF_CLIENTID_NULL;
+  owner_thread_id_ = 0;
 
   return S_OK;
 }
@@ -87,6 +112,74 @@ STDMETHODIMP OpenLessTextService::Deactivate() {
 HRESULT OpenLessTextService::SubmitTextFromPipe(
     const std::wstring& session_id,
     const std::wstring& text) {
+  if (GetCurrentThreadId() == owner_thread_id_) {
+    return CommitTextOnOwnerThread(session_id, text);
+  }
+
+  if (message_window_ == nullptr) {
+    return E_UNEXPECTED;
+  }
+
+  SubmitTextRequest request{&session_id, &text, E_UNEXPECTED};
+  DWORD_PTR message_result = 0;
+  const LRESULT sent = SendMessageTimeoutW(
+      message_window_, kSubmitTextMessage, 0,
+      reinterpret_cast<LPARAM>(&request), SMTO_ABORTIFHUNG,
+      kSubmitTextTimeoutMs, &message_result);
+  if (sent == 0) {
+    const DWORD error = GetLastError();
+    return HRESULT_FROM_WIN32(error != ERROR_SUCCESS ? error : ERROR_TIMEOUT);
+  }
+
+  return request.result;
+}
+
+HRESULT OpenLessTextService::StartIpcServer() {
+  pipe_server_.Start(this);
+  return S_OK;
+}
+
+void OpenLessTextService::StopIpcServer() {
+  pipe_server_.Stop();
+}
+
+HRESULT OpenLessTextService::EnsureMessageWindow() {
+  if (message_window_ != nullptr) {
+    return S_OK;
+  }
+
+  WNDCLASSW window_class = {};
+  window_class.lpfnWndProc = OpenLessTextService::MessageWindowProc;
+  window_class.hInstance = g_module;
+  window_class.lpszClassName = kMessageWindowClassName;
+
+  if (!RegisterClassW(&window_class)) {
+    const DWORD error = GetLastError();
+    if (error != ERROR_CLASS_ALREADY_EXISTS) {
+      return HRESULT_FROM_WIN32(error);
+    }
+  }
+
+  message_window_ =
+      CreateWindowExW(0, kMessageWindowClassName, L"", 0, 0, 0, 0, 0,
+                      HWND_MESSAGE, nullptr, g_module, this);
+  if (message_window_ == nullptr) {
+    return HRESULT_FROM_WIN32(GetLastError());
+  }
+
+  return S_OK;
+}
+
+void OpenLessTextService::DestroyMessageWindow() {
+  if (message_window_ != nullptr) {
+    DestroyWindow(message_window_);
+    message_window_ = nullptr;
+  }
+}
+
+HRESULT OpenLessTextService::CommitTextOnOwnerThread(
+    const std::wstring& session_id,
+    const std::wstring& text) {
   UNREFERENCED_PARAMETER(session_id);
 
   if (thread_mgr_ == nullptr || client_id_ == TF_CLIENTID_NULL) {
@@ -131,8 +224,32 @@ HRESULT OpenLessTextService::SubmitTextFromPipe(
   return edit_result;
 }
 
-HRESULT OpenLessTextService::StartIpcServer() {
-  return S_OK;
-}
+LRESULT CALLBACK OpenLessTextService::MessageWindowProc(HWND window,
+                                                        UINT message,
+                                                        WPARAM wparam,
+                                                        LPARAM lparam) {
+  UNREFERENCED_PARAMETER(wparam);
 
-void OpenLessTextService::StopIpcServer() {}
+  if (message == WM_NCCREATE) {
+    const auto* create = reinterpret_cast<CREATESTRUCTW*>(lparam);
+    SetWindowLongPtrW(window, GWLP_USERDATA,
+                      reinterpret_cast<LONG_PTR>(create->lpCreateParams));
+    return TRUE;
+  }
+
+  auto* service = reinterpret_cast<OpenLessTextService*>(
+      GetWindowLongPtrW(window, GWLP_USERDATA));
+  if (message == kSubmitTextMessage && service != nullptr) {
+    auto* request = reinterpret_cast<SubmitTextRequest*>(lparam);
+    if (request == nullptr || request->session_id == nullptr ||
+        request->text == nullptr) {
+      return 0;
+    }
+
+    request->result =
+        service->CommitTextOnOwnerThread(*request->session_id, *request->text);
+    return 1;
+  }
+
+  return DefWindowProcW(window, message, wparam, lparam);
+}
diff --git a/openless-all/app/windows-ime/src/text_service.h b/openless-all/app/windows-ime/src/text_service.h
index 7ef32466..d6402a6a 100644
--- a/openless-all/app/windows-ime/src/text_service.h
+++ b/openless-all/app/windows-ime/src/text_service.h
@@ -4,6 +4,8 @@
 #include <string>
 #include <windows.h>
 
+#include "ipc_client.h"
+
 class OpenLessTextService final : public ITfTextInputProcessorEx {
  public:
   OpenLessTextService();
@@ -27,8 +29,20 @@ class OpenLessTextService final : public ITfTextInputProcessorEx {
  private:
   HRESULT StartIpcServer();
   void StopIpcServer();
+  HRESULT EnsureMessageWindow();
+  void DestroyMessageWindow();
+  HRESULT CommitTextOnOwnerThread(const std::wstring& session_id,
+                                  const std::wstring& text);
+
+  static LRESULT CALLBACK MessageWindowProc(HWND window,
+                                            UINT message,
+                                            WPARAM wparam,
+                                            LPARAM lparam);
 
   LONG ref_count_ = 1;
   ITfThreadMgr* thread_mgr_ = nullptr;
   TfClientId client_id_ = TF_CLIENTID_NULL;
+  DWORD owner_thread_id_ = 0;
+  HWND message_window_ = nullptr;
+  OpenLessPipeServer pipe_server_;
 };