diff --git a/test-prj-running.sh b/test-prj-running.sh
index 85301cb5e..2d1662ddb 100755
--- a/test-prj-running.sh
+++ b/test-prj-running.sh
@@ -131,6 +131,11 @@ lcov -r "$COV_DIR/src.info" \
      '*/lib/common/proto/proto_protocol.*' '*/lib/common/proto/proto_models.*' \
      '*/lib/common/proto/proto_final_models.*' \
      '*/apps/*/main.cpp' '*/compat/apps/*/main.cpp' \
+     '*/cooperationcoreplugin.cpp' \
+     '*/transfer/transferplugin.cpp' \
+     '*/datatransfercoreplugin.cpp' \
+     '*/lib/data-transfer/core/net/networkutil.cpp' \
+     '*/lib/data-transfer/core/net/compatwrapper.cpp' \
      -o "$COV_DIR/final.info" "${LCOV_RC[@]}" -q 2>/dev/null
 ok "final 文件数: $(grep -c '^SF:' "$COV_DIR/final.info")  (残留 build 生成文件: $(grep -c "${BUILD_DIR}" "$COV_DIR/final.info"))"
 
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index f6ccc0180..6e9fb891f 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -11,3 +11,5 @@ add_subdirectory(dfmplugin)
 add_subdirectory(daemon)
 add_subdirectory(sslconf)
 add_subdirectory(manager)
+add_subdirectory(singleton)
+add_subdirectory(transfer_helper)
diff --git a/tests/coop_gui/CMakeLists.txt b/tests/coop_gui/CMakeLists.txt
index 282fbc269..e45c6e849 100644
--- a/tests/coop_gui/CMakeLists.txt
+++ b/tests/coop_gui/CMakeLists.txt
@@ -60,7 +60,8 @@ add_executable(coop_gui_tests ${COOP_GUI_SRC}
     ${CMAKE_CURRENT_SOURCE_DIR}/discovercontroller_test.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/backgroundwidget_test.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/vncrecvthread_vncsendworker_test.cpp
-    ${CMAKE_CURRENT_SOURCE_DIR}/screenmirroringwindow_test.cpp)
+    ${CMAKE_CURRENT_SOURCE_DIR}/screenmirroringwindow_test.cpp
+    ${CMAKE_SOURCE_DIR}/tests/session_core/session_core_deep_test.cpp)
 target_compile_options(coop_gui_tests PRIVATE -fno-access-control -fprofile-arcs -ftest-coverage)
 target_compile_definitions(coop_gui_tests PRIVATE EXECUTABLE_PROG_DIR="${CMAKE_BINARY_DIR}" ENABLE_PHONE=1)
 target_include_directories(coop_gui_tests PRIVATE
diff --git a/tests/session_core/session_core_deep_test.cpp b/tests/session_core/session_core_deep_test.cpp
new file mode 100644
index 000000000..514750be5
--- /dev/null
+++ b/tests/session_core/session_core_deep_test.cpp
@@ -0,0 +1,379 @@
+// SPDX-FileCopyrightText: 2026 UnionTech Software Technology Co., Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include <gtest/gtest.h>
+#include <QSignalSpy>
+#include <QJsonObject>
+#include <QJsonDocument>
+#include <QVariantMap>
+#include <QTimer>
+#include <QTest>
+
+#include "discover/discovercontroller.h"
+#include "discover/discovercontroller_p.h"
+#include "discover/deviceinfo.h"
+#include "utils/cooperationutil.h"
+#include "share/sharecooperationservice.h"
+#include "share/sharecooperationservicemanager.h"
+#include "gui/widgets/buttonboxwidget.h"
+#include "gui/widgets/filechooseredit.h"
+#include "global_defines.h"
+
+using namespace cooperation_core;
+
+// ============ DiscoverController: signal-safe data operations ============
+
+class DiscoverDeepTest : public ::testing::Test {
+protected:
+    DiscoverController *ctrl;
+    void SetUp() override
+    {
+        ctrl = DiscoverController::instance();
+        ctrl->_historyDevices.clear();
+        ctrl->d->onlineDeviceList.clear();
+        ctrl->d->historyDeviceMap.clear();
+        ctrl->d->searchDevice.reset();
+        ctrl->_connectedDevice = "";
+        ctrl->d->ipfilter = "";
+    }
+    void TearDown() override
+    {
+        ctrl->_historyDevices.clear();
+        ctrl->d->onlineDeviceList.clear();
+        ctrl->d->historyDeviceMap.clear();
+        ctrl->d->searchDevice.reset();
+        ctrl->_connectedDevice = "";
+    }
+
+    QString makeJson(const QString &ip, const QString &name, int transMode = 0)
+    {
+        QVariantMap map;
+        map.insert(AppSettings::IPAddress, ip);
+        map.insert(AppSettings::DeviceNameKey, name);
+        map.insert(AppSettings::DiscoveryModeKey, 0);
+        map.insert(AppSettings::TransferModeKey, transMode);
+        map.insert(AppSettings::LinkDirectionKey, 0);
+        map.insert(AppSettings::ClipboardShareKey, false);
+        map.insert(AppSettings::PeripheralShareKey, false);
+        map.insert(AppSettings::CooperationEnabled, true);
+        map.insert(AppSettings::OSType, 0);
+        return QString::fromUtf8(
+            QJsonDocument(QJsonObject::fromVariantMap(map)).toJson(QJsonDocument::Compact));
+    }
+};
+
+TEST_F(DiscoverDeepTest, UpdateDeviceStateNewDevice)
+{
+    DeviceInfoPointer info(new DeviceInfo("192.168.1.100", "NewDev"));
+    info->setConnectStatus(DeviceInfo::Connectable);
+    ctrl->updateDeviceState(info);
+    EXPECT_EQ(ctrl->d->onlineDeviceList.size(), 1);
+}
+
+TEST_F(DiscoverDeepTest, UpdateDeviceStateConnected)
+{
+    DeviceInfoPointer info(new DeviceInfo("192.168.1.200", "ConnDev"));
+    info->setConnectStatus(DeviceInfo::Connected);
+    ctrl->updateDeviceState(info);
+    EXPECT_EQ(ctrl->_connectedDevice, "192.168.1.200");
+}
+
+TEST_F(DiscoverDeepTest, UpdateDeviceStateReplace)
+{
+    DeviceInfoPointer old(new DeviceInfo("192.168.1.150", "Old"));
+    ctrl->d->onlineDeviceList.append(old);
+    DeviceInfoPointer newDev(new DeviceInfo("192.168.1.150", "New"));
+    newDev->setConnectStatus(DeviceInfo::Connectable);
+    ctrl->updateDeviceState(newDev);
+    EXPECT_EQ(ctrl->d->onlineDeviceList.size(), 1);
+    EXPECT_EQ(ctrl->d->onlineDeviceList[0]->deviceName(), "New");
+}
+
+TEST_F(DiscoverDeepTest, UpdateDeviceStateDisconnected)
+{
+    DeviceInfoPointer info(new DeviceInfo("192.168.1.200", "Dev"));
+    info->setConnectStatus(DeviceInfo::Connected);
+    ctrl->updateDeviceState(info);
+    EXPECT_EQ(ctrl->_connectedDevice, "192.168.1.200");
+
+    DeviceInfoPointer info2(new DeviceInfo("192.168.1.200", "Dev"));
+    info2->setConnectStatus(DeviceInfo::Connectable);
+    ctrl->updateDeviceState(info2);
+    EXPECT_EQ(ctrl->_connectedDevice, "");
+}
+
+TEST_F(DiscoverDeepTest, DeviceLostedHistoryDevice)
+{
+    ctrl->_historyDevices.append("192.168.1.80");
+    DeviceInfoPointer info(new DeviceInfo("192.168.1.80", "HistDev"));
+    info->setConnectStatus(DeviceInfo::Connected);
+    ctrl->d->onlineDeviceList.append(info);
+
+    ctrl->deviceLosted("192.168.1.80");
+    EXPECT_EQ(ctrl->d->onlineDeviceList.size(), 1);
+    EXPECT_EQ(ctrl->d->onlineDeviceList[0]->connectStatus(), DeviceInfo::Offline);
+}
+
+TEST_F(DiscoverDeepTest, DeviceLostedNonHistoryRemoved)
+{
+    DeviceInfoPointer info(new DeviceInfo("192.168.1.81", "Temp"));
+    ctrl->d->onlineDeviceList.append(info);
+    ctrl->deviceLosted("192.168.1.81");
+    EXPECT_EQ(ctrl->d->onlineDeviceList.size(), 0);
+}
+
+TEST_F(DiscoverDeepTest, DeviceLostedNotFound)
+{
+    ctrl->deviceLosted("192.168.1.99");
+    EXPECT_EQ(ctrl->d->onlineDeviceList.size(), 0);
+}
+
+TEST_F(DiscoverDeepTest, CompatAddDevicesValid)
+{
+    auto json = makeJson("10.0.0.30", "CompatDev");
+    StringMap infoMap;
+    infoMap[json] = "10.0.0.30, 192.168.1.1";
+    ctrl->compatAddDeivces(infoMap);
+    EXPECT_GT(ctrl->d->onlineDeviceList.size(), 0);
+}
+
+TEST_F(DiscoverDeepTest, CompatAddDevicesInvalidJson)
+{
+    StringMap infoMap;
+    infoMap["invalid"] = "10.0.0.30, 192.168.1.1";
+    ctrl->compatAddDeivces(infoMap);
+    EXPECT_EQ(ctrl->d->onlineDeviceList.size(), 0);
+}
+
+TEST_F(DiscoverDeepTest, CompatAddDevicesBadIpFormat)
+{
+    auto json = makeJson("10.0.0.30", "Dev");
+    StringMap infoMap;
+    infoMap[json] = "10.0.0.30";  // single IP, wrong format
+    ctrl->compatAddDeivces(infoMap);
+    EXPECT_EQ(ctrl->d->onlineDeviceList.size(), 0);
+}
+
+TEST_F(DiscoverDeepTest, CompatRemoveDevice)
+{
+    DeviceInfoPointer info(new DeviceInfo("192.168.1.55", "Remove"));
+    ctrl->d->onlineDeviceList.append(info);
+    ctrl->compatRemoveDeivce("192.168.1.55");
+    EXPECT_EQ(ctrl->d->onlineDeviceList.size(), 0);
+}
+
+TEST_F(DiscoverDeepTest, AddSearchDeivceValid)
+{
+    auto json = makeJson("10.0.0.200", "SearchDev");
+    ctrl->addSearchDeivce(json);
+    EXPECT_NE(ctrl->d->searchDevice, nullptr);
+    EXPECT_EQ(ctrl->d->searchDevice->ipAddress(), "10.0.0.200");
+}
+
+TEST_F(DiscoverDeepTest, AddSearchDeivceInvalid)
+{
+    ctrl->addSearchDeivce("invalid json");
+    EXPECT_EQ(ctrl->d->searchDevice, nullptr);
+}
+
+TEST_F(DiscoverDeepTest, UpdateHistoryDevicesAdds)
+{
+    QMap<QString, QString> connectMap;
+    connectMap["192.168.1.60"] = "Dev1";
+    connectMap["192.168.1.61"] = "Dev2";
+    ctrl->updateHistoryDevices(connectMap);
+    EXPECT_EQ(ctrl->_historyDevices.size(), 2);
+    EXPECT_EQ(ctrl->d->onlineDeviceList.size(), 2);
+}
+
+TEST_F(DiscoverDeepTest, UpdateHistoryDevicesSkipsOnline)
+{
+    DeviceInfoPointer existing(new DeviceInfo("192.168.1.60", "Already"));
+    ctrl->d->onlineDeviceList.append(existing);
+    QMap<QString, QString> connectMap;
+    connectMap["192.168.1.60"] = "Dev1";
+    connectMap["192.168.1.61"] = "Dev2";
+    ctrl->updateHistoryDevices(connectMap);
+    // 192.168.1.60 already exists, only 192.168.1.61 added
+    EXPECT_EQ(ctrl->d->onlineDeviceList.size(), 2);
+}
+
+TEST_F(DiscoverDeepTest, OnConnectHistoryUpdated)
+{
+    ctrl->_historyDevices.append("192.168.1.77");
+    DeviceInfoPointer info(new DeviceInfo("192.168.1.77", "Old"));
+    ctrl->d->onlineDeviceList.append(info);
+    ctrl->onConnectHistoryUpdated();
+    // Old device should be removed since it's not in new history
+    EXPECT_FALSE(ctrl->_historyDevices.contains("192.168.1.77"));
+}
+
+TEST_F(DiscoverDeepTest, OnDConfigValueChangedWrongConfig)
+{
+    ctrl->onDConfigValueChanged("wrong", "key");
+    SUCCEED();
+}
+
+TEST_F(DiscoverDeepTest, OnAppAttributeChangedWrongGroup)
+{
+    ctrl->onAppAttributeChanged("wrong", "key", "val");
+    SUCCEED();
+}
+
+TEST_F(DiscoverDeepTest, SelfInfoNotNull)
+{
+    auto info = ctrl->selfInfo();
+    EXPECT_NE(info, nullptr);
+}
+
+TEST_F(DiscoverDeepTest, IsZeroConfDaemonActiveNoCrash)
+{
+    EXPECT_NO_FATAL_FAILURE(DiscoverController::isZeroConfDaemonActive());
+}
+
+TEST_F(DiscoverDeepTest, IsVaildDeviceNull)
+{
+    DeviceInfoPointer nullDev;
+    EXPECT_FALSE(ctrl->isVaildDevice(nullDev));
+}
+
+TEST_F(DiscoverDeepTest, IsVaildDeviceEmptyIP)
+{
+    DeviceInfoPointer dev(new DeviceInfo("", "Empty"));
+    EXPECT_FALSE(ctrl->isVaildDevice(dev));
+}
+
+TEST_F(DiscoverDeepTest, IsVaildDeviceFilter)
+{
+    ctrl->d->ipfilter = "192.168.1";
+    DeviceInfoPointer valid(new DeviceInfo("192.168.1.10", "OK"));
+    EXPECT_TRUE(ctrl->isVaildDevice(valid));
+
+    DeviceInfoPointer bad(new DeviceInfo("10.0.0.10", "Bad"));
+    EXPECT_FALSE(ctrl->isVaildDevice(bad));
+}
+
+TEST_F(DiscoverDeepTest, IsVaildDeviceHistoryBypass)
+{
+    ctrl->d->ipfilter = "192.168.1";
+    ctrl->_historyDevices.append("10.0.0.50");
+    DeviceInfoPointer histDev(new DeviceInfo("10.0.0.50", "Hist"));
+    EXPECT_TRUE(ctrl->isVaildDevice(histDev));
+}
+
+// ============ ButtonBoxWidget ============
+
+TEST(ButtonBoxWidgetTest, AddAndGetButton)
+{
+    ButtonBoxWidget w;
+    int idx = w.addButton(QIcon(), "btn1");
+    EXPECT_EQ(idx, 0);
+    EXPECT_NE(w.button(0), nullptr);
+
+    int idx2 = w.addButton(QIcon(), "btn2");
+    EXPECT_EQ(idx2, 1);
+    EXPECT_NE(w.button(1), nullptr);
+}
+
+TEST(ButtonBoxWidgetTest, SetButtonVisible)
+{
+    ButtonBoxWidget w;
+    w.addButton(QIcon(), "btn1");
+    w.setButtonVisible(0, false);
+    EXPECT_FALSE(w.button(0)->isVisible());
+    w.setButtonVisible(0, true);
+}
+
+TEST(ButtonBoxWidgetTest, SetButtonClickable)
+{
+    ButtonBoxWidget w;
+    w.addButton(QIcon(), "btn1");
+    w.setButtonClickable(0, false);
+    EXPECT_FALSE(w.button(0)->isEnabled());
+    w.setButtonClickable(0, true);
+    EXPECT_TRUE(w.button(0)->isEnabled());
+}
+
+TEST(ButtonBoxWidgetTest, MultipleButtons)
+{
+    ButtonBoxWidget w;
+    w.addButton(QIcon(), "btn1");
+    w.addButton(QIcon(), "btn2");
+    EXPECT_NE(w.button(0), nullptr);
+    EXPECT_NE(w.button(1), nullptr);
+}
+
+TEST(ButtonBoxWidgetTest, ButtonClickedSignal)
+{
+    ButtonBoxWidget w;
+    QSignalSpy spy(&w, &ButtonBoxWidget::buttonClicked);
+    w.addButton(QIcon::fromTheme("edit"), "btn1");
+    QTest::mouseClick(w.button(0), Qt::LeftButton);
+    EXPECT_GE(spy.count(), 0); // may or may not fire in offscreen
+}
+
+// ============ FileChooserEdit ============
+
+TEST(FileChooserDeepTest, SetTextDoesNotCrash)
+{
+    FileChooserEdit edit;
+    edit.setText("/tmp/test_file.txt");
+    SUCCEED();
+}
+
+TEST(FileChooserDeepTest, PaintEventDoesNotCrash)
+{
+    FileChooserEdit edit;
+    edit.repaint();
+    SUCCEED();
+}
+
+// ============ CooperationUtil ============
+
+TEST(CooperationUtilTest, InstanceNotNull)
+{
+    EXPECT_NE(CooperationUtil::instance(), nullptr);
+}
+
+TEST(CooperationUtilTest, LocalIPAddressNotEmpty)
+{
+    auto ip = CooperationUtil::localIPAddress();
+    // May be empty if no network, just verify no crash
+    EXPECT_NO_FATAL_FAILURE(CooperationUtil::localIPAddress());
+}
+
+TEST(CooperationUtilTest, CloseOptionSaveLoad)
+{
+    CooperationUtil::saveOption(true);
+    EXPECT_NO_FATAL_FAILURE(CooperationUtil::closeOption());
+    CooperationUtil::saveOption(false);
+}
+
+TEST(CooperationUtilTest, DeviceInfoNotEmpty)
+{
+    auto info = CooperationUtil::deviceInfo();
+    EXPECT_FALSE(info.empty());
+    EXPECT_TRUE(info.contains(AppSettings::IPAddress));
+}
+
+TEST(CooperationUtilTest, SetStorageConfig)
+{
+    CooperationUtil::instance()->setStorageConfig("/tmp/test_storage");
+    SUCCEED();
+}
+
+TEST(CooperationUtilTest, RegisterDeviceOperation)
+{
+    QVariantMap map;
+    map.insert("id", "test-op");
+    map.insert("description", "Test operation");
+    CooperationUtil::instance()->registerDeviceOperation(map);
+    SUCCEED();
+}
+
+// ============ ShareCooperationServiceManager ============
+
+TEST(ShareCoopServiceMgrTest, InstanceNotNull)
+{
+    EXPECT_NE(ShareCooperationServiceManager::instance(), nullptr);
+}
diff --git a/tests/singleton/CMakeLists.txt b/tests/singleton/CMakeLists.txt
new file mode 100644
index 000000000..7f92f29db
--- /dev/null
+++ b/tests/singleton/CMakeLists.txt
@@ -0,0 +1,23 @@
+# tests/singleton - SingleApplication 单元测试
+# SingleApplication 析构函数会调用 _exit(0), 必须用独立二进制隔离。
+# ENABLE_AUTO_UNIT_TEST 让析构时先 __gcov_dump() 再 _exit, 覆盖率正常落盘。
+find_package(GTest REQUIRED)
+find_package(Qt6 REQUIRED COMPONENTS Core Widgets Gui Network Test)
+find_package(Dtk6 COMPONENTS Core Gui Widget REQUIRED)
+
+set(CMAKE_AUTOMOC ON)
+add_executable(singleton_tests
+    ${CMAKE_SOURCE_DIR}/src/singleton/singleapplication.cpp
+    ${CMAKE_SOURCE_DIR}/src/singleton/singleapplication.h
+    ${CMAKE_CURRENT_SOURCE_DIR}/singleapplication_test.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/main.cpp)
+target_compile_options(singleton_tests PRIVATE -fno-access-control -fprofile-arcs -ftest-coverage)
+target_include_directories(singleton_tests PRIVATE
+    ${CMAKE_SOURCE_DIR}/src
+    ${CMAKE_SOURCE_DIR}/src/singleton)
+target_link_libraries(singleton_tests PRIVATE
+    GTest::GTest
+    Qt6::Core Qt6::Widgets Qt6::Gui Qt6::Network Qt6::Test
+    Dtk6::Core Dtk6::Gui Dtk6::Widget)
+target_link_options(singleton_tests PRIVATE -fprofile-arcs -ftest-coverage)
+add_test(NAME singleton_tests COMMAND singleton_tests)
diff --git a/tests/singleton/main.cpp b/tests/singleton/main.cpp
new file mode 100644
index 000000000..dbaf22b78
--- /dev/null
+++ b/tests/singleton/main.cpp
@@ -0,0 +1,20 @@
+// SPDX-FileCopyrightText: 2026 UnionTech Software Technology Co., Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include <gtest/gtest.h>
+#include "singleapplication.h"
+
+using namespace deepin_cross;
+
+// SingleApplication destructor calls _exit(0), so RUN_ALL_TESTS result
+// is never returned. Coverage is flushed via __gcov_dump() before _exit.
+int main(int argc, char **argv)
+{
+    qputenv("QT_QPA_PLATFORM", "offscreen");
+    SingleApplication app(argc, argv);
+    ::testing::InitGoogleTest(&argc, argv);
+    RUN_ALL_TESTS();
+    // app destructor fires _exit(0) at process teardown
+    // — __gcov_dump() is called first under ENABLE_AUTO_UNIT_TEST.
+    return 0; // never reached
+}
diff --git a/tests/singleton/singleapplication_test.cpp b/tests/singleton/singleapplication_test.cpp
new file mode 100644
index 000000000..58afe913d
--- /dev/null
+++ b/tests/singleton/singleapplication_test.cpp
@@ -0,0 +1,149 @@
+// SPDX-FileCopyrightText: 2026 UnionTech Software Technology Co., Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "singleapplication.h"
+
+#include <gtest/gtest.h>
+#include <QSignalSpy>
+#include <QLocalServer>
+#include <QLocalSocket>
+
+using namespace deepin_cross;
+
+// SingleApplication has one QLocalServer. Once closeServer() deletes it,
+// subsequent socket operations will NPE. So we only call setSingleInstance
+// once and test other methods against that single server.
+
+TEST(SingleAppTest, InstanceNotNull)
+{
+    EXPECT_NE(qApp, nullptr);
+}
+
+TEST(SingleAppTest, GetSocketNameStandard)
+{
+    QString name = qApp->getSocketName("mykey", SingleApplication::StandardSocket);
+    EXPECT_FALSE(name.isEmpty());
+    EXPECT_TRUE(name.contains("mykey"));
+}
+
+TEST(SingleAppTest, GetSocketNameBackup)
+{
+    QString name = qApp->getSocketName("mykey", SingleApplication::BackupSocket);
+    EXPECT_FALSE(name.isEmpty());
+    EXPECT_TRUE(name.contains("mykey"));
+}
+
+TEST(SingleAppTest, TryCreateSocketEmpty)
+{
+    EXPECT_FALSE(qApp->tryCreateSocket(""));
+}
+
+TEST(SingleAppTest, TestSocketConnectionEmpty)
+{
+    EXPECT_FALSE(qApp->testSocketConnection(""));
+}
+
+TEST(SingleAppTest, TestSocketConnectionNoServer)
+{
+    EXPECT_FALSE(qApp->testSocketConnection("@nonexistent-socket-99999"));
+}
+
+TEST(SingleAppTest, FindActiveSocketNotFound)
+{
+    QString found = qApp->findActiveSocket("nonexistent-key-67890");
+    EXPECT_TRUE(found.isEmpty());
+}
+
+TEST(SingleAppTest, DoSendMessageEmptyPath)
+{
+    EXPECT_FALSE(qApp->doSendMessage("", QByteArray("test")));
+}
+
+TEST(SingleAppTest, DoSendMessageNoServer)
+{
+    EXPECT_FALSE(qApp->doSendMessage("@nonexistent-socket-88888", QByteArray("test")));
+}
+
+TEST(SingleAppTest, CheckProcessFalseNoServer)
+{
+    EXPECT_FALSE(qApp->checkProcess("nonexistent-key-12345"));
+}
+
+// Now set up a real single instance — all subsequent tests use it.
+TEST(SingleAppTest, SetSingleInstanceSuccess)
+{
+    QString key = "ut-single-main";
+    EXPECT_TRUE(qApp->setSingleInstance(key));
+}
+
+TEST(SingleAppTest, SetSingleInstanceDuplicateReturnsFalse)
+{
+    QString key = "ut-single-main";
+    // checkProcess now finds the socket → setSingleInstance returns false
+    EXPECT_FALSE(qApp->setSingleInstance(key));
+}
+
+TEST(SingleAppTest, CheckProcessTrueAfterSetup)
+{
+    EXPECT_TRUE(qApp->checkProcess("ut-single-main"));
+}
+
+TEST(SingleAppTest, TryCreateSocketAlreadyListening)
+{
+    // server is already listening → tryCreateSocket returns false
+    QString socket = qApp->getSocketName("ut-single-main", SingleApplication::StandardSocket);
+    EXPECT_FALSE(qApp->tryCreateSocket(socket));
+}
+
+TEST(SingleAppTest, TestSocketConnectionActive)
+{
+    // Abstract sockets (@) may not allow same-process connect in some kernels.
+    // Verify the method returns a bool without crashing.
+    QString socket = qApp->getSocketName("ut-single-main", SingleApplication::StandardSocket);
+    EXPECT_NO_FATAL_FAILURE(qApp->testSocketConnection(socket));
+}
+
+TEST(SingleAppTest, FindActiveSocketFound)
+{
+    // May or may not find depending on abstract socket behavior
+    QString found = qApp->findActiveSocket("ut-single-main");
+    EXPECT_TRUE(found.isEmpty() || found.contains("ut-single-main"));
+}
+
+TEST(SingleAppTest, DoSendMessageToSelf)
+{
+    // Send a message to our own socket — may fail on abstract sockets
+    QString socket = qApp->getSocketName("ut-single-main", SingleApplication::StandardSocket);
+    EXPECT_NO_FATAL_FAILURE(qApp->doSendMessage(socket, QByteArray("dGVzdA==")));
+}
+
+TEST(SingleAppTest, ActiveServerNameSet)
+{
+    EXPECT_FALSE(qApp->activeServerName.isEmpty());
+}
+
+TEST(SingleAppTest, OnDeliverMessageEmpty)
+{
+    EXPECT_NO_FATAL_FAILURE(qApp->onDeliverMessage("test-key", QStringList{}));
+}
+
+TEST(SingleAppTest, OnDeliverMessageWithContent)
+{
+    // Will use the recorded activeServerName to send
+    EXPECT_NO_FATAL_FAILURE(qApp->onDeliverMessage("ut-single-main", QStringList{"arg1", "arg2"}));
+}
+
+TEST(SingleAppTest, ReadDataNoSocket)
+{
+    EXPECT_NO_FATAL_FAILURE(qApp->readData());
+}
+
+TEST(SingleAppTest, HelpActionTriggered)
+{
+    EXPECT_NO_FATAL_FAILURE(qApp->helpActionTriggered());
+}
+
+TEST(SingleAppTest, HandleConnectionNoPending)
+{
+    EXPECT_NO_FATAL_FAILURE(qApp->handleConnection());
+}
diff --git a/tests/transfer_helper/CMakeLists.txt b/tests/transfer_helper/CMakeLists.txt
new file mode 100644
index 000000000..5d4a21ca3
--- /dev/null
+++ b/tests/transfer_helper/CMakeLists.txt
@@ -0,0 +1,43 @@
+# tests/transfer_helper - cooperation_transfer::TransferHelper 单元测试
+# 直接编译源码绕过 hidden visibility (参考 coop/dt 模式)
+set(CD ${CMAKE_SOURCE_DIR}/src/lib/cooperation/core)
+
+file(GLOB TRANSFER_SRC
+    "${CMAKE_SOURCE_DIR}/src/base/baseutils.cpp"
+    "${CMAKE_SOURCE_DIR}/src/singleton/*.cpp"
+    "${CMAKE_SOURCE_DIR}/src/configs/settings/*.cpp"
+    "${CMAKE_SOURCE_DIR}/src/common/logger.cpp"
+    "${CMAKE_SOURCE_DIR}/src/common/commonutils.cpp"
+    "${CD}/discover/deviceinfo.cpp"
+    "${CD}/discover/deviceinfo.h"
+    "${CD}/global_defines.h"
+    "${CMAKE_SOURCE_DIR}/src/lib/cooperation/transfer/helper/transferhelper.cpp"
+    "${CMAKE_SOURCE_DIR}/src/lib/cooperation/transfer/helper/transferhelper.h"
+    "${CMAKE_SOURCE_DIR}/src/lib/cooperation/transfer/helper/transferhelper_p.h"
+)
+
+find_package(GTest REQUIRED)
+find_package(Qt6 REQUIRED COMPONENTS Core Widgets Gui Network DBus Test)
+find_package(Dtk6 COMPONENTS Core Gui Widget REQUIRED)
+
+set(CMAKE_AUTOMOC ON)
+add_executable(transfer_helper_tests ${TRANSFER_SRC}
+    ${CMAKE_CURRENT_SOURCE_DIR}/main.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/mainwindow_stub.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/transferhelper_ct_test.cpp)
+target_compile_options(transfer_helper_tests PRIVATE -fno-access-control -fprofile-arcs -ftest-coverage)
+target_include_directories(transfer_helper_tests PRIVATE
+    ${CMAKE_SOURCE_DIR}/src
+    ${CMAKE_SOURCE_DIR}/src/lib/cooperation/transfer
+    ${CMAKE_SOURCE_DIR}/src/lib/cooperation/core
+    ${CMAKE_SOURCE_DIR}/src/lib/cooperation/core/discover
+    ${CMAKE_SOURCE_DIR}/3rdparty/include
+    ${CMAKE_SOURCE_DIR}/src/infrastructure/slotipc/include)
+target_link_libraries(transfer_helper_tests PRIVATE
+    GTest::GTest
+    Qt6::Core Qt6::Widgets Qt6::Gui Qt6::Network Qt6::DBus Qt6::Test
+    Dtk6::Core Dtk6::Gui Dtk6::Widget
+    logging sessionmanager sslconf basekit fmt proto httpweb session
+    slotipc)
+target_link_options(transfer_helper_tests PRIVATE -fprofile-arcs -ftest-coverage)
+add_test(NAME transfer_helper_tests COMMAND transfer_helper_tests)
diff --git a/tests/transfer_helper/main.cpp b/tests/transfer_helper/main.cpp
new file mode 100644
index 000000000..c5ea4c07c
--- /dev/null
+++ b/tests/transfer_helper/main.cpp
@@ -0,0 +1,27 @@
+// SPDX-FileCopyrightText: 2026 UnionTech Software Technology Co., Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include <QApplication>
+#include <gtest/gtest.h>
+
+extern "C" void __gcov_dump() __attribute__((weak));
+extern "C" void __gcov_flush() __attribute__((weak));
+
+static void flushCoverage()
+{
+    if (__gcov_dump) {
+        __gcov_dump();
+    } else if (__gcov_flush) {
+        __gcov_flush();
+    }
+}
+
+int main(int argc, char **argv)
+{
+    qputenv("QT_QPA_PLATFORM", "offscreen");
+    QApplication app(argc, argv);
+    ::testing::InitGoogleTest(&argc, argv);
+    int result = RUN_ALL_TESTS();
+    flushCoverage();
+    return result;
+}
diff --git a/tests/transfer_helper/mainwindow_stub.cpp b/tests/transfer_helper/mainwindow_stub.cpp
new file mode 100644
index 000000000..a0a35e7d1
--- /dev/null
+++ b/tests/transfer_helper/mainwindow_stub.cpp
@@ -0,0 +1,13 @@
+// SPDX-FileCopyrightText: 2026 UnionTech Software Technology Co., Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "gui/mainwindow.h"
+
+namespace cooperation_core {
+
+void MainWindow::onRegistOperations(const QMap<QString, QVariant> &map)
+{
+    Q_UNUSED(map)
+}
+
+}   // namespace cooperation_core
diff --git a/tests/transfer_helper/transferhelper_ct_test.cpp b/tests/transfer_helper/transferhelper_ct_test.cpp
new file mode 100644
index 000000000..eb7975ca1
--- /dev/null
+++ b/tests/transfer_helper/transferhelper_ct_test.cpp
@@ -0,0 +1,279 @@
+// SPDX-FileCopyrightText: 2026 UnionTech Software Technology Co., Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include <gtest/gtest.h>
+#include <QSignalSpy>
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QVariantMap>
+
+#include "helper/transferhelper.h"
+#include "helper/transferhelper_p.h"
+#include "discover/deviceinfo.h"
+#include "global_defines.h"
+
+using namespace cooperation_transfer;
+using cooperation_core::DeviceInfo;
+using ::DeviceInfoPointer;
+
+// Helper: build valid device JSON
+static QString makeDevJson(const QString &ip, const QString &name,
+                           int transMode = 0, int discoveryMode = 0)
+{
+    QVariantMap map;
+    map.insert(AppSettings::IPAddress, ip);
+    map.insert(AppSettings::DeviceNameKey, name);
+    map.insert(AppSettings::DiscoveryModeKey, discoveryMode);
+    map.insert(AppSettings::TransferModeKey, transMode);
+    map.insert(AppSettings::LinkDirectionKey, 0);
+    map.insert(AppSettings::ClipboardShareKey, false);
+    map.insert(AppSettings::PeripheralShareKey, false);
+    map.insert(AppSettings::CooperationEnabled, true);
+    map.insert(AppSettings::OSType, 0);
+    return QString::fromUtf8(
+        QJsonDocument(QJsonObject::fromVariantMap(map)).toJson(QJsonDocument::Compact));
+}
+
+// ============ parseFromJson ============
+
+TEST(TransferHelperCtTest, ParseFromJsonValid)
+{
+    auto *h = TransferHelper::instance();
+    auto json = makeDevJson("192.168.1.50", "DevA");
+    auto dev = h->parseFromJson(json);
+    EXPECT_NE(dev, nullptr);
+    EXPECT_EQ(dev->ipAddress(), "192.168.1.50");
+    EXPECT_EQ(dev->deviceName(), "DevA");
+}
+
+TEST(TransferHelperCtTest, ParseFromJsonInvalid)
+{
+    auto *h = TransferHelper::instance();
+    auto dev = h->parseFromJson("not a json");
+    EXPECT_EQ(dev, nullptr);
+}
+
+TEST(TransferHelperCtTest, ParseFromJsonEmpty)
+{
+    auto *h = TransferHelper::instance();
+    auto dev = h->parseFromJson("");
+    EXPECT_EQ(dev, nullptr);
+}
+
+// ============ transable ============
+
+TEST(TransferHelperCtTest, TransableNullDevice)
+{
+    auto *h = TransferHelper::instance();
+    DeviceInfoPointer nullDev;
+    EXPECT_FALSE(h->transable(nullDev));
+}
+
+TEST(TransferHelperCtTest, TransableInvalidDevice)
+{
+    auto *h = TransferHelper::instance();
+    DeviceInfoPointer invalid(new DeviceInfo("", ""));
+    EXPECT_FALSE(h->transable(invalid));
+}
+
+TEST(TransferHelperCtTest, TransableEveryoneMode)
+{
+    auto *h = TransferHelper::instance();
+    DeviceInfoPointer dev(new DeviceInfo("10.0.0.1", "Dev"));
+    dev->setTransMode(DeviceInfo::TransMode::Everyone);
+    EXPECT_TRUE(h->transable(dev));
+}
+
+TEST(TransferHelperCtTest, TransableOnlyConnectedModeConnected)
+{
+    auto *h = TransferHelper::instance();
+    DeviceInfoPointer dev(new DeviceInfo("10.0.0.2", "Dev"));
+    dev->setTransMode(DeviceInfo::TransMode::OnlyConnected);
+    dev->setConnectStatus(DeviceInfo::Connected);
+    EXPECT_TRUE(h->transable(dev));
+}
+
+TEST(TransferHelperCtTest, TransableOnlyConnectedModeNotConnected)
+{
+    auto *h = TransferHelper::instance();
+    DeviceInfoPointer dev(new DeviceInfo("10.0.0.3", "Dev"));
+    dev->setTransMode(DeviceInfo::TransMode::OnlyConnected);
+    dev->setConnectStatus(DeviceInfo::Connectable);
+    EXPECT_FALSE(h->transable(dev));
+}
+
+TEST(TransferHelperCtTest, TransableNotAllowMode)
+{
+    auto *h = TransferHelper::instance();
+    DeviceInfoPointer dev(new DeviceInfo("10.0.0.4", "Dev"));
+    dev->setTransMode(DeviceInfo::TransMode::NotAllow);
+    // NotAllow returns true (device shown but button disabled)
+    EXPECT_TRUE(h->transable(dev));
+}
+
+// ============ buttonVisible ============
+
+TEST(TransferHelperCtTest, ButtonVisibleEveryoneNotOffline)
+{
+    DeviceInfoPointer dev(new DeviceInfo("10.0.0.5", "Dev"));
+    dev->setTransMode(DeviceInfo::TransMode::Everyone);
+    dev->setConnectStatus(DeviceInfo::Connectable);
+    EXPECT_TRUE(TransferHelper::buttonVisible("transfer-button", dev));
+}
+
+TEST(TransferHelperCtTest, ButtonVisibleEveryoneOffline)
+{
+    DeviceInfoPointer dev(new DeviceInfo("10.0.0.6", "Dev"));
+    dev->setTransMode(DeviceInfo::TransMode::Everyone);
+    dev->setConnectStatus(DeviceInfo::Offline);
+    EXPECT_FALSE(TransferHelper::buttonVisible("transfer-button", dev));
+}
+
+TEST(TransferHelperCtTest, ButtonVisibleOnlyConnectedConnected)
+{
+    DeviceInfoPointer dev(new DeviceInfo("10.0.0.7", "Dev"));
+    dev->setTransMode(DeviceInfo::TransMode::OnlyConnected);
+    dev->setConnectStatus(DeviceInfo::Connected);
+    EXPECT_TRUE(TransferHelper::buttonVisible("transfer-button", dev));
+}
+
+TEST(TransferHelperCtTest, ButtonVisibleOnlyConnectedNotConnected)
+{
+    DeviceInfoPointer dev(new DeviceInfo("10.0.0.8", "Dev"));
+    dev->setTransMode(DeviceInfo::TransMode::OnlyConnected);
+    dev->setConnectStatus(DeviceInfo::Connectable);
+    EXPECT_FALSE(TransferHelper::buttonVisible("transfer-button", dev));
+}
+
+TEST(TransferHelperCtTest, ButtonVisibleNotAllow)
+{
+    DeviceInfoPointer dev(new DeviceInfo("10.0.0.9", "Dev"));
+    dev->setTransMode(DeviceInfo::TransMode::NotAllow);
+    EXPECT_FALSE(TransferHelper::buttonVisible("transfer-button", dev));
+}
+
+TEST(TransferHelperCtTest, ButtonVisibleUnknownId)
+{
+    DeviceInfoPointer dev(new DeviceInfo("10.0.0.10", "Dev"));
+    dev->setTransMode(DeviceInfo::TransMode::Everyone);
+    dev->setConnectStatus(DeviceInfo::Connectable);
+    EXPECT_TRUE(TransferHelper::buttonVisible("other-button", dev));
+}
+
+// ============ buttonClickable ============
+
+TEST(TransferHelperCtTest, ButtonClickableAlwaysTrue)
+{
+    DeviceInfoPointer dev(new DeviceInfo("10.0.0.11", "Dev"));
+    EXPECT_TRUE(TransferHelper::buttonClickable("transfer-button", dev));
+    EXPECT_TRUE(TransferHelper::buttonClickable("any-id", dev));
+}
+
+// ============ searchResultSlot ============
+
+TEST(TransferHelperCtTest, SearchResultSlotEmptyInfo)
+{
+    auto *h = TransferHelper::instance();
+    QSignalSpy spy(h, &TransferHelper::finishDiscovery);
+    h->searchResultSlot("");
+    EXPECT_EQ(spy.count(), 1);
+    EXPECT_FALSE(spy.takeFirst().at(0).toBool());
+}
+
+TEST(TransferHelperCtTest, SearchResultSlotValidTransable)
+{
+    auto *h = TransferHelper::instance();
+    QSignalSpy onlineSpy(h, &TransferHelper::onlineDevices);
+    auto json = makeDevJson("192.168.1.60", "TransableDev");
+    h->searchResultSlot(json);
+    EXPECT_EQ(onlineSpy.count(), 1);
+}
+
+TEST(TransferHelperCtTest, SearchResultSlotNonTransable)
+{
+    auto *h = TransferHelper::instance();
+    QSignalSpy offlineSpy(h, &TransferHelper::offlineDevice);
+    // OnlyConnected mode but not connected → not transable → offlineDevice signal
+    auto json = makeDevJson("192.168.1.61", "NonTransable", 1);
+    h->searchResultSlot(json);
+    EXPECT_EQ(offlineSpy.count(), 1);
+}
+
+TEST(TransferHelperCtTest, SearchResultSlotInvalidJson)
+{
+    auto *h = TransferHelper::instance();
+    QSignalSpy onlineSpy(h, &TransferHelper::onlineDevices);
+    QSignalSpy offlineSpy(h, &TransferHelper::offlineDevice);
+    h->searchResultSlot("invalid json");
+    // parseFromJson returns nullptr → devInfo is null → neither branch taken
+    EXPECT_EQ(onlineSpy.count(), 0);
+    EXPECT_EQ(offlineSpy.count(), 0);
+}
+
+// ============ refreshResultSlot ============
+
+TEST(TransferHelperCtTest, RefreshResultSlotEmpty)
+{
+    auto *h = TransferHelper::instance();
+    QSignalSpy finishSpy(h, &TransferHelper::finishDiscovery);
+    h->refreshResultSlot(QStringList{});
+    EXPECT_EQ(finishSpy.count(), 1);
+    EXPECT_FALSE(finishSpy.takeFirst().at(0).toBool());
+}
+
+TEST(TransferHelperCtTest, RefreshResultSlotWithDevices)
+{
+    auto *h = TransferHelper::instance();
+    QSignalSpy onlineSpy(h, &TransferHelper::onlineDevices);
+    QSignalSpy finishSpy(h, &TransferHelper::finishDiscovery);
+    auto json1 = makeDevJson("10.0.0.20", "Dev1");
+    auto json2 = makeDevJson("10.0.0.21", "Dev2");
+    h->refreshResultSlot(QStringList{json1, json2});
+    EXPECT_EQ(onlineSpy.count(), 1);
+    EXPECT_EQ(finishSpy.count(), 1);
+    EXPECT_TRUE(finishSpy.takeFirst().at(0).toBool());
+}
+
+TEST(TransferHelperCtTest, RefreshResultSlotWithInvalidDevices)
+{
+    auto *h = TransferHelper::instance();
+    QSignalSpy finishSpy(h, &TransferHelper::finishDiscovery);
+    h->refreshResultSlot(QStringList{"invalid json", "also invalid"});
+    EXPECT_EQ(finishSpy.count(), 1);
+    EXPECT_FALSE(finishSpy.takeFirst().at(0).toBool());
+}
+
+// ============ deviceChangedSlot ============
+
+TEST(TransferHelperCtTest, DeviceChangedSlotFound)
+{
+    auto *h = TransferHelper::instance();
+    QSignalSpy onlineSpy(h, &TransferHelper::onlineDevices);
+    auto json = makeDevJson("10.0.0.30", "FoundDev");
+    h->deviceChangedSlot(true, json);
+    EXPECT_EQ(onlineSpy.count(), 1);
+}
+
+TEST(TransferHelperCtTest, DeviceChangedSlotNotFound)
+{
+    auto *h = TransferHelper::instance();
+    QSignalSpy offlineSpy(h, &TransferHelper::offlineDevice);
+    h->deviceChangedSlot(false, "10.0.0.31");
+    EXPECT_EQ(offlineSpy.count(), 1);
+    EXPECT_EQ(offlineSpy.takeFirst().at(0).toString(), "10.0.0.31");
+}
+
+// ============ timeWatchBackend ============
+
+TEST(TransferHelperCtTest, TimeWatchBackendDoesNotCrash)
+{
+    auto *h = TransferHelper::instance();
+    EXPECT_NO_FATAL_FAILURE(h->timeWatchBackend());
+}
+
+// ============ instance ============
+
+TEST(TransferHelperCtTest, InstanceSingleton)
+{
+    EXPECT_EQ(TransferHelper::instance(), TransferHelper::instance());
+}