diff --git a/CMakeLists.txt b/CMakeLists.txt
index 750e143441..120b85596c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -66,6 +66,10 @@ endif()
 add_subdirectory(CuteLogger)
 add_subdirectory(src)
 add_subdirectory(translations)
+include(CTest)
+if(BUILD_TESTING)
+  add_subdirectory(tests)
+endif()
 
 feature_summary(WHAT ALL INCLUDE_QUIET_PACKAGES FATAL_ON_MISSING_REQUIRED_PACKAGES)
 
diff --git a/scripts/build-shotcut-msys2.sh b/scripts/build-shotcut-msys2.sh
index 639cdd722b..0a494db701 100755
--- a/scripts/build-shotcut-msys2.sh
+++ b/scripts/build-shotcut-msys2.sh
@@ -615,7 +615,7 @@ function set_globals {
 
   #####
   # shotcut
-  CONFIG[4]="cmake -G Ninja -D CMAKE_INSTALL_PREFIX=$FINAL_INSTALL_DIR -DCMAKE_PREFIX_PATH=$QTDIR -D SHOTCUT_VERSION=$SHOTCUT_VERSION $CMAKE_DEBUG_FLAG"
+  CONFIG[4]="cmake -G Ninja -D CMAKE_INSTALL_PREFIX=$FINAL_INSTALL_DIR -DCMAKE_PREFIX_PATH=$QTDIR -D SHOTCUT_VERSION=$SHOTCUT_VERSION -D BUILD_TESTING=OFF $CMAKE_DEBUG_FLAG"
   CFLAGS_[4]="$ASAN_CFLAGS $CFLAGS"
   LDFLAGS_[4]="$ASAN_LDFLAGS $LDFLAGS"
   BUILD[4]="ninja -j $MAKEJ"
diff --git a/scripts/build-shotcut.sh b/scripts/build-shotcut.sh
index c5209f8e72..6c7d4d7c4c 100755
--- a/scripts/build-shotcut.sh
+++ b/scripts/build-shotcut.sh
@@ -918,7 +918,7 @@ function set_globals {
 
   #####
   # shotcut
-  CONFIG[7]="cmake -G Ninja -D CMAKE_PREFIX_PATH=$QTDIR -D SHOTCUT_VERSION=$SHOTCUT_VERSION $CMAKE_DEBUG_FLAG"
+  CONFIG[7]="cmake -G Ninja -D CMAKE_PREFIX_PATH=$QTDIR -D SHOTCUT_VERSION=$SHOTCUT_VERSION -D BUILD_TESTING=OFF $CMAKE_DEBUG_FLAG"
   if test "$TARGET_OS" = "Darwin" ; then
     CONFIG[7]="${CONFIG[7]} -D CMAKE_INSTALL_PREFIX=."
     CONFIG[7]="${CONFIG[7]} -D CMAKE_OSX_ARCHITECTURES='arm64;x86_64'"
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 1662ae669f..f551c64ab7 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,6 +1,6 @@
 find_package(Qt6 REQUIRED COMPONENTS Core)
 
-add_executable(shotcut WIN32 MACOSX_BUNDLE
+add_library(shotcut_objects OBJECT
   abstractproducerwidget.cpp abstractproducerwidget.h
   actions.cpp actions.h
   autosavefile.cpp autosavefile.h
@@ -79,7 +79,6 @@ add_executable(shotcut WIN32 MACOSX_BUNDLE
   jobs/screencapturejob.cpp jobs/screencapturejob.h
   jobs/videoqualityjob.cpp jobs/videoqualityjob.h
   jobs/whisperjob.cpp jobs/whisperjob.h
-  main.cpp
   mainwindow.cpp mainwindow.h
   mainwindow.ui
   mltcontroller.cpp mltcontroller.h
@@ -233,6 +232,9 @@ add_executable(shotcut WIN32 MACOSX_BUNDLE
   ../icons/resources.qrc
 )
 
+add_executable(shotcut WIN32 MACOSX_BUNDLE main.cpp)
+target_link_libraries(shotcut PRIVATE shotcut_objects)
+
 add_custom_target(OTHER_FILES
   SOURCES
   ../.github/ISSUE_TEMPLATE.md
@@ -266,8 +268,8 @@ add_custom_target(OTHER_FILES
   ../scripts/staple.sh
 )
 
-target_link_libraries(shotcut
-  PRIVATE
+target_link_libraries(shotcut_objects
+  PUBLIC
   CuteLogger
   PkgConfig::mlt++
   PkgConfig::FFTW
@@ -284,22 +286,22 @@ target_link_libraries(shotcut
   Qt6::Xml
 )
 if(UNIX AND NOT APPLE)
-  target_link_libraries(shotcut PRIVATE Qt6::DBus X11::X11)
-  target_sources(shotcut PRIVATE linuxtools.cpp linuxtools.h)
+  target_link_libraries(shotcut_objects PUBLIC Qt6::DBus X11::X11)
+  target_sources(shotcut_objects PRIVATE linuxtools.cpp linuxtools.h)
 endif()
 
 file(GLOB_RECURSE QML_SRC "qml/*")
-target_sources(shotcut PRIVATE ${QML_SRC})
+target_sources(shotcut_objects PRIVATE ${QML_SRC})
 
-target_include_directories(shotcut PRIVATE ${CMAKE_SOURCE_DIR}/CuteLogger/include)
-target_compile_definitions(shotcut PRIVATE SHOTCUT_VERSION="${SHOTCUT_VERSION}")
+target_include_directories(shotcut_objects PUBLIC ${CMAKE_SOURCE_DIR}/CuteLogger/include)
+target_compile_definitions(shotcut_objects PUBLIC SHOTCUT_VERSION="${SHOTCUT_VERSION}")
 
 # Add compile definitions when certain custom cache variables are ON
 if(EXTERNAL_LAUNCHERS)
-  target_compile_definitions(shotcut PRIVATE EXTERNAL_LAUNCHERS)
+  target_compile_definitions(shotcut_objects PUBLIC EXTERNAL_LAUNCHERS)
 endif()
 if(USE_VULKAN)
-  target_compile_definitions(shotcut PRIVATE USE_VULKAN)
+  target_compile_definitions(shotcut_objects PUBLIC USE_VULKAN)
 endif()
 
 if(WIN32)
@@ -309,22 +311,22 @@ if(WIN32)
   target_sources(shotcut PRIVATE ${CMAKE_SOURCE_DIR}/packaging/windows/shotcut.rc)
 
   # Windows integration features
-  target_sources(shotcut PRIVATE windowstools.cpp windowstools.h)
-  target_sources(shotcut PRIVATE widgets/d3dvideowidget.h widgets/d3dvideowidget.cpp)
-  target_sources(shotcut PRIVATE widgets/openglvideowidget.h widgets/openglvideowidget.cpp)
-  target_link_libraries(shotcut PRIVATE d3d11 d3dcompiler ole32)
+  target_sources(shotcut_objects PRIVATE windowstools.cpp windowstools.h)
+  target_sources(shotcut_objects PRIVATE widgets/d3dvideowidget.h widgets/d3dvideowidget.cpp)
+  target_sources(shotcut_objects PRIVATE widgets/openglvideowidget.h widgets/openglvideowidget.cpp)
+  target_link_libraries(shotcut_objects PUBLIC d3d11 d3dcompiler ole32)
 
   # Runtime exception handler for debug only
   if(CMAKE_SYSTEM_PROCESSOR STREQUAL "AMD64")
-    target_include_directories(shotcut PRIVATE ${CMAKE_SOURCE_DIR}/drmingw/include)
-    target_link_directories(shotcut PRIVATE ${CMAKE_SOURCE_DIR}/drmingw/x64/lib)
+    target_include_directories(shotcut_objects PUBLIC ${CMAKE_SOURCE_DIR}/drmingw/include)
+    target_link_directories(shotcut_objects PUBLIC ${CMAKE_SOURCE_DIR}/drmingw/x64/lib)
     target_link_libraries(shotcut PRIVATE debug exchndl)
   endif()
 
   if(WINDOWS_DEPLOY)
     install(TARGETS shotcut RUNTIME DESTINATION ${CMAKE_INSTALL_PREFIX})
   else()
-    target_compile_definitions(shotcut PRIVATE NODEPLOY)
+    target_compile_definitions(shotcut_objects PUBLIC NODEPLOY)
     install(TARGETS shotcut RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
   endif()
 
@@ -332,18 +334,18 @@ if(WIN32)
   install(DIRECTORY ${CMAKE_SOURCE_DIR}/filter-sets DESTINATION ${CMAKE_INSTALL_PREFIX}/share/shotcut/)
   install(DIRECTORY ${CMAKE_SOURCE_DIR}/voices DESTINATION ${CMAKE_INSTALL_PREFIX}/share/shotcut/)
 else()
-    target_sources(shotcut PRIVATE widgets/openglvideowidget.h widgets/openglvideowidget.cpp)
+    target_sources(shotcut_objects PRIVATE widgets/openglvideowidget.h widgets/openglvideowidget.cpp)
 endif()
 
 if(APPLE)
-  target_sources(shotcut PRIVATE macos.mm macos.h
+  target_sources(shotcut_objects PRIVATE macos.mm macos.h
     widgets/metalvideowidget.h widgets/metalvideowidget.mm)
   set_target_properties(shotcut PROPERTIES
     OUTPUT_NAME "Shotcut"
     MACOSX_BUNDLE_INFO_PLIST ${CMAKE_SOURCE_DIR}/packaging/macos/Info.plist.in)
   find_library(FOUNDATION Foundation)
   find_library(COCOA Cocoa)
-  target_link_libraries(shotcut PRIVATE ${FOUNDATION} ${COCOA})
+  target_link_libraries(shotcut_objects PUBLIC ${FOUNDATION} ${COCOA})
   set(APP_ICON ${CMAKE_SOURCE_DIR}/packaging/macos/shotcut.icns)
   target_sources(shotcut PRIVATE ${APP_ICON})
   set_source_files_properties(${APP_ICON} PROPERTIES MACOSX_PACKAGE_LOCATION "Resources")
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
new file mode 100644
index 0000000000..b009d087e4
--- /dev/null
+++ b/tests/CMakeLists.txt
@@ -0,0 +1 @@
+add_subdirectory(mainwindow)
diff --git a/tests/mainwindow/CMakeLists.txt b/tests/mainwindow/CMakeLists.txt
new file mode 100644
index 0000000000..a4f7855fd3
--- /dev/null
+++ b/tests/mainwindow/CMakeLists.txt
@@ -0,0 +1,10 @@
+find_package(Qt6 REQUIRED COMPONENTS Test)
+
+add_executable(test_mainwindow mainwindowtest.cpp)
+target_link_libraries(test_mainwindow PRIVATE shotcut_objects Qt6::Test)
+target_include_directories(test_mainwindow PRIVATE ${CMAKE_SOURCE_DIR}/src)
+
+add_test(NAME MainWindowTest COMMAND test_mainwindow)
+set_tests_properties(MainWindowTest PROPERTIES
+    ENVIRONMENT "QT_QPA_PLATFORM=offscreen"
+)
diff --git a/tests/mainwindow/mainwindowtest.cpp b/tests/mainwindow/mainwindowtest.cpp
new file mode 100644
index 0000000000..35235855aa
--- /dev/null
+++ b/tests/mainwindow/mainwindowtest.cpp
@@ -0,0 +1,377 @@
+/*
+ * Copyright (c) 2026 Meltytech, LLC
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "actions.h"
+#include "mainwindow.h"
+#include "mltcontroller.h"
+
+#include <ConsoleAppender.h>
+#include <Logger.h>
+
+#include <QFileInfo>
+#include <QSignalSpy>
+#include <QStandardPaths>
+#include <QTest>
+#include <QUndoStack>
+
+class TestMainWindow : public QObject
+{
+    Q_OBJECT
+private slots:
+    void initTestCase()
+    {
+        QStandardPaths::setTestModeEnabled(true);
+
+        // Mirror the setup done by Application in main.cpp
+        QCoreApplication::setOrganizationName("Meltytech");
+        QCoreApplication::setOrganizationDomain("shotcut.org");
+        QCoreApplication::setApplicationName("Shotcut");
+        QCoreApplication::setApplicationVersion(SHOTCUT_VERSION);
+
+        // Suppress CuteLogger output: register an appender at Fatal level only
+        // so the "no appenders" fallback to stderr is never triggered.
+        auto *appender = new ConsoleAppender;
+        appender->setDetailsLevel(Logger::Fatal);
+        cuteLogger->registerAppender(appender);
+    }
+
+    // ── LayoutMode enum ──────────────────────────────────────────────────────
+    void test_layoutModeEnumValues()
+    {
+        QCOMPARE(static_cast<int>(MainWindow::Custom), 0);
+        QCOMPARE(static_cast<int>(MainWindow::Logging), 1);
+        QCOMPARE(static_cast<int>(MainWindow::Editing), 2);
+        QCOMPARE(static_cast<int>(MainWindow::Effects), 3);
+        QCOMPARE(static_cast<int>(MainWindow::Color), 4);
+        QCOMPARE(static_cast<int>(MainWindow::Audio), 5);
+        QCOMPARE(static_cast<int>(MainWindow::PlayerOnly), 6);
+    }
+
+    // ── Singleton ────────────────────────────────────────────────────────────
+    void test_singletonReturnsSameInstance()
+    {
+        MainWindow &w1 = MAIN;
+        MainWindow &w2 = MAIN;
+        QVERIFY(&w1 == &w2);
+    }
+
+    // ── Initial file / project state ─────────────────────────────────────────
+    void test_initialFileNameIsEmpty()
+    {
+        QVERIFY(MAIN.fileName().isEmpty());
+    }
+
+    void test_initialMultitrackNotValid()
+    {
+        QVERIFY(!MAIN.isMultitrackValid());
+    }
+
+    void test_initialPlaylistNotValid()
+    {
+        QVERIFY(!MAIN.isPlaylistValid());
+    }
+
+    void test_initialClipboardNotNewer()
+    {
+        QVERIFY(!MAIN.isClipboardNewer());
+    }
+
+    // ── Undo stack ───────────────────────────────────────────────────────────
+    void test_undoStackNotNull()
+    {
+        QVERIFY(MAIN.undoStack() != nullptr);
+    }
+
+    void test_undoStackInitiallyClean()
+    {
+        QVERIFY(MAIN.undoStack()->isClean());
+    }
+
+    void test_undoStackCannotUndoInitially()
+    {
+        QVERIFY(!MAIN.undoStack()->canUndo());
+    }
+
+    void test_undoStackCannotRedoInitially()
+    {
+        QVERIFY(!MAIN.undoStack()->canRedo());
+    }
+
+    // ── Dock and controller pointers ─────────────────────────────────────────
+    void test_playlistDockNotNull()
+    {
+        QVERIFY(MAIN.playlistDock() != nullptr);
+    }
+
+    void test_timelineDockNotNull()
+    {
+        QVERIFY(MAIN.timelineDock() != nullptr);
+    }
+
+    void test_filterControllerNotNull()
+    {
+        QVERIFY(MAIN.filterController() != nullptr);
+    }
+
+    void test_customProfileMenuNotNull()
+    {
+        QVERIFY(MAIN.customProfileMenu() != nullptr);
+    }
+
+    void test_actionAddCustomProfileNotNull()
+    {
+        QVERIFY(MAIN.actionAddCustomProfile() != nullptr);
+    }
+
+    void test_actionProfileRemoveNotNull()
+    {
+        QVERIFY(MAIN.actionProfileRemove() != nullptr);
+    }
+
+    void test_profileGroupNotNull()
+    {
+        QVERIFY(MAIN.profileGroup() != nullptr);
+    }
+
+    // ── Window properties ────────────────────────────────────────────────────
+    void test_windowAcceptDrops()
+    {
+        QVERIFY(MAIN.acceptDrops());
+    }
+
+    void test_windowNotModifiedInitially()
+    {
+        QVERIFY(!MAIN.isWindowModified());
+    }
+
+    void test_windowDockNestingEnabled()
+    {
+        QVERIFY(MAIN.isDockNestingEnabled());
+    }
+
+    void test_windowTitleContainsApplicationName()
+    {
+        QVERIFY(MAIN.windowTitle().contains(QCoreApplication::applicationName()));
+    }
+
+    // ── File path helpers ─────────────────────────────────────────────────────
+    void test_untitledFileNameEndsWithUntitledMlt()
+    {
+        QVERIFY(MAIN.untitledFileName().endsWith("__untitled__.mlt"));
+    }
+
+    void test_untitledFileNameIsAbsolutePath()
+    {
+        QVERIFY(QFileInfo(MAIN.untitledFileName()).isAbsolute());
+    }
+
+    // ── Dock visibility ───────────────────────────────────────────────────────
+    void test_keyframesDockNotVisibleInitially()
+    {
+        QVERIFY(!MAIN.keyframesDockIsVisible());
+    }
+
+    // ── Player actions registered ─────────────────────────────────────────────
+    void test_actionPlayerPlayPauseRegistered()
+    {
+        QVERIFY(Actions["playerPlayPauseAction"] != nullptr);
+    }
+
+    void test_actionPlayerLoopRegistered()
+    {
+        QVERIFY(Actions["playerLoopAction"] != nullptr);
+    }
+
+    void test_actionPlayerFastForwardRegistered()
+    {
+        QVERIFY(Actions["playerFastForwardAction"] != nullptr);
+    }
+
+    void test_actionPlayerRewindRegistered()
+    {
+        QVERIFY(Actions["playerRewindAction"] != nullptr);
+    }
+
+    void test_actionPlayerSkipNextRegistered()
+    {
+        QVERIFY(Actions["playerSkipNextAction"] != nullptr);
+    }
+
+    void test_actionPlayerSkipPreviousRegistered()
+    {
+        QVERIFY(Actions["playerSkipPreviousAction"] != nullptr);
+    }
+
+    void test_actionPlayerSeekStartRegistered()
+    {
+        QVERIFY(Actions["playerSeekStartAction"] != nullptr);
+    }
+
+    void test_actionPlayerSeekEndRegistered()
+    {
+        QVERIFY(Actions["playerSeekEndAction"] != nullptr);
+    }
+
+    void test_actionPlayerNextFrameRegistered()
+    {
+        QVERIFY(Actions["playerNextFrameAction"] != nullptr);
+    }
+
+    void test_actionPlayerPreviousFrameRegistered()
+    {
+        QVERIFY(Actions["playerPreviousFrameAction"] != nullptr);
+    }
+
+    // ── MainWindow actions registered ─────────────────────────────────────────
+    void test_actionTimelineReloadRegistered()
+    {
+        QVERIFY(Actions["timelineReload"] != nullptr);
+    }
+
+    void test_actionPropertiesRenameClipRegistered()
+    {
+        QVERIFY(Actions["propertiesRenameClipAction"] != nullptr);
+    }
+
+    void test_actionRecentFindRegistered()
+    {
+        QVERIFY(Actions["recentFindAction"] != nullptr);
+    }
+
+    void test_actionAnalyzeFiltersRegistered()
+    {
+        QVERIFY(Actions["analyzeFilters"] != nullptr);
+    }
+
+    // ── Timeline dock actions registered ─────────────────────────────────────
+    void test_actionTimelineAddAudioTrackRegistered()
+    {
+        QVERIFY(Actions["timelineAddAudioTrackAction"] != nullptr);
+    }
+
+    void test_actionTimelineAddVideoTrackRegistered()
+    {
+        QVERIFY(Actions["timelineAddVideoTrackAction"] != nullptr);
+    }
+
+    void test_actionTimelineInsertTrackRegistered()
+    {
+        QVERIFY(Actions["timelineInsertTrackAction"] != nullptr);
+    }
+
+    void test_actionTimelineSelectAllRegistered()
+    {
+        QVERIFY(Actions["timelineSelectAllAction"] != nullptr);
+    }
+
+    void test_actionTimelineSelectNoneRegistered()
+    {
+        QVERIFY(Actions["timelineSelectNoneAction"] != nullptr);
+    }
+
+    void test_actionTimelineToggleTrackLockedRegistered()
+    {
+        QVERIFY(Actions["timelineToggleTrackLockedAction"] != nullptr);
+    }
+
+    void test_actionTimelineToggleTrackMuteRegistered()
+    {
+        QVERIFY(Actions["timelineToggleTrackMuteAction"] != nullptr);
+    }
+
+    // ── Filters dock actions registered ──────────────────────────────────────
+    void test_actionFiltersAddFilterRegistered()
+    {
+        QVERIFY(Actions["filtersAddFilterAction"] != nullptr);
+    }
+
+    void test_actionFiltersRemoveFilterRegistered()
+    {
+        QVERIFY(Actions["filtersRemoveFilterAction"] != nullptr);
+    }
+
+    void test_actionFiltersCopyFiltersRegistered()
+    {
+        QVERIFY(Actions["filtersCopyFiltersAction"] != nullptr);
+    }
+
+    void test_actionFiltersPasteFiltersRegistered()
+    {
+        QVERIFY(Actions["filtersPasteFiltersAction"] != nullptr);
+    }
+
+    // ── Files and playlist dock actions registered ────────────────────────────
+    void test_actionFilesSearchRegistered()
+    {
+        QVERIFY(Actions["filesSearch"] != nullptr);
+    }
+
+    void test_actionPlaylistSearchRegistered()
+    {
+        QVERIFY(Actions["playlistSearch"] != nullptr);
+    }
+
+    // ── MLT profile ───────────────────────────────────────────────────────────
+    void test_mltProfileWidthPositive()
+    {
+        QVERIFY(MLT.profile().width() > 0);
+    }
+
+    void test_mltProfileHeightPositive()
+    {
+        QVERIFY(MLT.profile().height() > 0);
+    }
+
+    void test_mltProfileFpsPositive()
+    {
+        QVERIFY(MLT.profile().fps() > 0.0);
+    }
+
+    // ── Timeline empty-state helpers ──────────────────────────────────────────
+    void test_bottomVideoTrackIndexNegativeWithEmptyTimeline()
+    {
+        QCOMPARE(MAIN.bottomVideoTrackIndex(), -1);
+    }
+
+    void test_mltIndexForTrackNegativeWithEmptyTimeline()
+    {
+        QCOMPARE(MAIN.mltIndexForTrack(0), -1);
+    }
+
+    // ── isSourceClipMyProject ─────────────────────────────────────────────────
+    void test_isSourceClipMyProjectReturnsFalseForEmptyPath()
+    {
+        QVERIFY(!MAIN.isSourceClipMyProject("", false));
+    }
+
+    void test_isSourceClipMyProjectReturnsFalseForNonMatchingPath()
+    {
+        QVERIFY(!MAIN.isSourceClipMyProject("/nonexistent/file.mp4", false));
+    }
+
+    // ── Signal emission ───────────────────────────────────────────────────────
+    void test_setProfileEmitsProfileChanged()
+    {
+        QSignalSpy spy(&MAIN, &MainWindow::profileChanged);
+        MAIN.setProfile("dv_pal");
+        QCOMPARE(spy.count(), 1);
+        MAIN.setProfile(""); // restore to automatic
+    }
+};
+
+QTEST_MAIN(TestMainWindow)
+#include "mainwindowtest.moc"