From: Vitaly Zdanevich <zdanevich.vitaly@ya.ru>
Subject: [PATCH] Support system backend manifests and explicit desktop integrations

Keep user manifests authoritative and allow distribution builds to disable
automatically detected X11 and Wayland integrations. Test the installed
manifest search with isolated XDG directories.

--- a/fronts/qt/src/Rpc/BackendManifest.cpp
+++ b/fronts/qt/src/Rpc/BackendManifest.cpp
@@ -109,6 +109,11 @@
     const QString configHome = QStandardPaths::writableLocation(QStandardPaths::GenericConfigLocation);
     scanDir(QDir(configHome + QStringLiteral("/cloudmus/backends.d")), result, seenIds);

+	// Distribution packages install shared manifests in the XDG data paths.
+	// User configuration is scanned first so it continues to override them.
+	for (const QString& dataDir : QStandardPaths::standardLocations(QStandardPaths::GenericDataLocation))
+		scanDir(QDir(dataDir + QStringLiteral("/cloudmus/backends.d")), result, seenIds);
+
 #ifdef Q_OS_WIN
     scanDir(QDir(QCoreApplication::applicationDirPath() + QStringLiteral("/backends")), result, seenIds, true);
 #endif
--- a/fronts/qt/CMakeLists.txt
+++ b/fronts/qt/CMakeLists.txt
@@ -517,12 +517,16 @@
 # (xcb). Each is optional; without them, the system's KF6WindowSystem is
 # loaded at runtime instead, which works only next to the Qt it was built
 # against (not in the AppImage).
-find_package(Qt6 QUIET OPTIONAL_COMPONENTS GuiPrivate)
-if(NOT WIN32)
+option(CLOUDMUS_WAYLAND "Build native Wayland blur integration" ON)
+option(CLOUDMUS_X11 "Build native X11 blur and global hotkeys" ON)
+if(CLOUDMUS_WAYLAND)
+    find_package(Qt6 QUIET OPTIONAL_COMPONENTS GuiPrivate)
+endif()
+if(NOT WIN32 AND CLOUDMUS_WAYLAND)
     pkg_check_modules(WAYLAND_CLIENT QUIET IMPORTED_TARGET wayland-client)
     find_program(WAYLAND_SCANNER wayland-scanner)
 endif()
-if(TARGET Qt6::GuiPrivate AND WAYLAND_CLIENT_FOUND AND WAYLAND_SCANNER)
+if(CLOUDMUS_WAYLAND AND TARGET Qt6::GuiPrivate AND WAYLAND_CLIENT_FOUND AND WAYLAND_SCANNER)
     set(BLUR_GENERATED_DIR ${CMAKE_CURRENT_BINARY_DIR}/generated_wayland)
     # Protocol copies in third_party/: the distro's wayland-protocols is
     # too old for ext-background-effect on the AppImage's Debian 11 base.
@@ -548,10 +552,10 @@
     target_link_libraries(cloudmus-ui PRIVATE Qt6::GuiPrivate PkgConfig::WAYLAND_CLIENT)
     message(STATUS "Glass: Wayland blur protocols, built in")
 endif()
-if(NOT WIN32)
+if(NOT WIN32 AND CLOUDMUS_X11)
     pkg_check_modules(XCB QUIET IMPORTED_TARGET xcb)
 endif()
-if(XCB_FOUND)
+if(CLOUDMUS_X11 AND XCB_FOUND)
     target_compile_definitions(cloudmus-ui PRIVATE CLOUDMUS_BLUR_X11 CLOUDMUS_HOTKEYS_X11)
     target_sources(cloudmus-ui PRIVATE src/Integration/GlobalHotkeysX11.cpp)
     target_link_libraries(cloudmus-ui PRIVATE PkgConfig::XCB)
@@ -638,6 +642,9 @@

 # --- tests (QtTest): `ctest --test-dir build`, or run build/bin/cloudmus-qt-tests.
 if(BUILD_TESTING)
+add_executable(cloudmus-backend-manifest-tests tests/BackendManifestTest.cpp)
+target_link_libraries(cloudmus-backend-manifest-tests PRIVATE cloudmus-core Qt6::Test)
+add_test(NAME cloudmus-backend-manifest-tests COMMAND cloudmus-backend-manifest-tests)
 add_executable(cloudmus-qt-tests
     tests/main.cpp
     tests/FakeBackend.cpp
--- /dev/null
+++ b/fronts/qt/tests/BackendManifestTest.cpp
@@ -0,0 +1,82 @@
+#include <QCoreApplication>
+#include <QDir>
+#include <QFile>
+#include <QJsonArray>
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QTemporaryDir>
+#include <QTest>
+
+#include "BackendManifest.h"
+
+// Exercise installed backend discovery without touching a real user's files.
+class BackendManifestTest : public QObject {
+	Q_OBJECT
+
+private:
+	QTemporaryDir root;
+
+	void writeManifest(const QString& base, const QString& name)
+	{
+		const QString path = root.path() + base + QStringLiteral("/cloudmus/backends.d");
+		QVERIFY(QDir().mkpath(path));
+		QFile icon(path + QStringLiteral("/local.svg"));
+		QVERIFY(icon.open(QIODevice::WriteOnly));
+		icon.write("<svg/>");
+		QFile file(path + QStringLiteral("/local.json"));
+		QVERIFY(file.open(QIODevice::WriteOnly));
+		const QJsonObject manifest {
+			{ "id", "local-folder" }, { "name", name },
+			{ "argv", QJsonArray { "/usr/bin/python3.14", "-m", "cloudmus_backend_local" } },
+			{ "protocolVersion", "1.12" }, { "icon", "local.svg" }
+		};
+		file.write(QJsonDocument(manifest).toJson());
+	}
+
+private slots:
+	void init()
+	{
+		QVERIFY(root.isValid());
+		qputenv("XDG_CONFIG_HOME", (root.path() + "/config").toUtf8());
+		qputenv("XDG_DATA_HOME", (root.path() + "/data").toUtf8());
+		qputenv("XDG_DATA_DIRS", (root.path() + "/system").toUtf8());
+		qunsetenv("CLOUDMUS_DEV_BACKENDS");
+	}
+
+	void cleanup()
+	{
+		for (const auto& path : { "/config", "/data", "/system" })
+			QVERIFY(QDir(root.path() + path).removeRecursively());
+	}
+
+	void discoversSystemBackendAndRelativeIcon()
+	{
+		writeManifest("/system", "System backend");
+		const auto manifests = Rpc::discoverManifests();
+		QCOMPARE(manifests.size(), 1);
+		QCOMPARE(manifests.first().name, QStringLiteral("System backend"));
+		QCOMPARE(manifests.first().argv.first(), QStringLiteral("/usr/bin/python3.14"));
+		QCOMPARE(manifests.first().iconPath, root.path() + "/system/cloudmus/backends.d/local.svg");
+	}
+
+	void userConfigurationOverridesSystemBackend()
+	{
+		writeManifest("/system", "System backend");
+		writeManifest("/config", "User backend");
+		const auto manifests = Rpc::discoverManifests();
+		QCOMPARE(manifests.size(), 1);
+		QCOMPARE(manifests.first().name, QStringLiteral("User backend"));
+	}
+
+	void userDataOverridesSystemBackend()
+	{
+		writeManifest("/system", "System backend");
+		writeManifest("/data", "User data backend");
+		const auto manifests = Rpc::discoverManifests();
+		QCOMPARE(manifests.size(), 1);
+		QCOMPARE(manifests.first().name, QStringLiteral("User data backend"));
+	}
+};
+
+QTEST_GUILESS_MAIN(BackendManifestTest)
+#include "BackendManifestTest.moc"