Add Nebula.Windows with Sway IPC backend

Introduces a new `core/windows` module (`Nebula.Windows`) with `WindowService`, window/workspace models, and a Sway IPC backend for live window tracking and control (focus, close, move/resize, snap, maximize/restore, minimize, workspace switch). The desktop shell now links this module, uses compositor focus for top-bar active app text, and adds an Open Windows section in the launcher with focus/close actions.

Also updates application metadata handling to parse `StartupWMClass` and map window `app_id`/class to friendly names and icons, and revises Sway config/docs for the new floating-first Desktop 0.2 behavior with temporary compositor-provided decorations.

core/applications/ApplicationModel.cpp

@@ -91,3 +91,49 @@ const DesktopEntry *ApplicationModel::entryById(const QString &desktopId) const
     }
     return nullptr;
 }
+
+const DesktopEntry *ApplicationModel::entryMatchingWindow(const QString &appId, const QString &windowClass) const
+{
+    auto stem = [](QString value) {
+        if (value.endsWith(QLatin1String(".desktop"), Qt::CaseInsensitive))
+            value.chop(8);
+        return value.toLower();
+    };
+
+    const QString app = stem(appId);
+    const QString cls = stem(windowClass);
+    const QString appLast = app.contains(QLatin1Char('.')) ? app.section(QLatin1Char('.'), -1) : app;
+    const QString classLast = cls.contains(QLatin1Char('.')) ? cls.section(QLatin1Char('.'), -1) : cls;
+
+    const DesktopEntry *wmClassMatch = nullptr;
+    const DesktopEntry *lastComponentMatch = nullptr;
+
+    for (const DesktopEntry &entry : m_entries) {
+        const QString id = stem(entry.desktopId);
+        if (!app.isEmpty() && id == app)
+            return &entry;
+        if (!cls.isEmpty() && id == cls)
+            return &entry;
+
+        if (!entry.startupWmClass.isEmpty()) {
+            const QString wm = stem(entry.startupWmClass);
+            if ((!app.isEmpty() && wm == app) || (!cls.isEmpty() && wm == cls)
+                || (!appLast.isEmpty() && wm == appLast) || (!classLast.isEmpty() && wm == classLast)) {
+                if (!wmClassMatch)
+                    wmClassMatch = &entry;
+            }
+        }
+
+        if (!lastComponentMatch) {
+            const QString idLast = id.contains(QLatin1Char('.')) ? id.section(QLatin1Char('.'), -1) : id;
+            if (appLast.size() >= 3 && (id == appLast || idLast == appLast))
+                lastComponentMatch = &entry;
+            else if (classLast.size() >= 3 && (id == classLast || idLast == classLast))
+                lastComponentMatch = &entry;
+        }
+    }
+
+    if (wmClassMatch)
+        return wmClassMatch;
+    return lastComponentMatch;
+}

core/applications/ApplicationModel.hpp

@@ -35,6 +35,7 @@ public:
     void setEntries(QVector<DesktopEntry> entries);
     const DesktopEntry *entryAt(int row) const;
     const DesktopEntry *entryById(const QString &desktopId) const;
+    const DesktopEntry *entryMatchingWindow(const QString &appId, const QString &windowClass) const;
 
 signals:
     void countChanged();

core/applications/ApplicationService.cpp

@@ -7,13 +7,21 @@
 #include <QFileInfo>
 #include <QSet>
 #include <QVector>
+#include <QtGlobal>
 #include <utility>
 
+namespace {
+ApplicationService *s_instance = nullptr;
+}
+
 ApplicationService::ApplicationService(QObject *parent)
     : QObject(parent)
     , m_model(new ApplicationModel(this))
     , m_filtered(new ApplicationFilterModel(this))
 {
+    if (!s_instance)
+        s_instance = this;
+
     m_filtered->setSourceModel(m_model);
     m_filtered->setSortRole(ApplicationModel::NameRole);
     m_filtered->sort(0, Qt::AscendingOrder);
@@ -24,6 +32,17 @@ ApplicationService::ApplicationService(QObject *parent)
     refresh();
 }
 
+ApplicationService::~ApplicationService()
+{
+    if (s_instance == this)
+        s_instance = nullptr;
+}
+
+ApplicationService *ApplicationService::instance()
+{
+    return s_instance;
+}
+
 ApplicationService *ApplicationService::create(QQmlEngine *engine, QJSEngine *)
 {
     auto *service = new ApplicationService(engine);
@@ -66,6 +85,22 @@ bool ApplicationService::launch(const QString &desktopId) const
     return entry->launch();
 }
 
+QString ApplicationService::displayNameForWindow(const QString &appId, const QString &windowClass) const
+{
+    const DesktopEntry *entry = m_model->entryMatchingWindow(appId, windowClass);
+    if (entry && !entry->name.isEmpty())
+        return entry->name;
+    return {};
+}
+
+QString ApplicationService::iconNameForWindow(const QString &appId, const QString &windowClass) const
+{
+    const DesktopEntry *entry = m_model->entryMatchingWindow(appId, windowClass);
+    if (entry)
+        return entry->icon;
+    return {};
+}
+
 void ApplicationService::refresh()
 {
     QVector<DesktopEntry> entries;

core/applications/ApplicationService.hpp

@@ -20,7 +20,10 @@ class ApplicationService : public QObject
 
 public:
     explicit ApplicationService(QObject *parent = nullptr);
+    ~ApplicationService() override;
+
     static ApplicationService *create(QQmlEngine *engine, QJSEngine *scriptEngine);
+    static ApplicationService *instance();
 
     ApplicationModel *model() const;
     ApplicationFilterModel *filteredModel() const;
@@ -30,6 +33,8 @@ public:
     int count() const;
 
     Q_INVOKABLE bool launch(const QString &desktopId) const;
+    Q_INVOKABLE QString displayNameForWindow(const QString &appId, const QString &windowClass) const;
+    Q_INVOKABLE QString iconNameForWindow(const QString &appId, const QString &windowClass) const;
     Q_INVOKABLE void refresh();
 
 signals:

core/applications/DesktopEntry.cpp

@@ -353,6 +353,8 @@ DesktopEntry parseDesktopEntryFile(const QString &filePath, const QString &deskt
             entry.exec = value;
         else if (key == QLatin1String("TryExec"))
             entry.tryExec = value;
+        else if (key == QLatin1String("StartupWMClass"))
+            entry.startupWmClass = value;
         else if (key == QLatin1String("Icon"))
             entry.icon = value;
         else if (key == QLatin1String("Path"))

core/applications/DesktopEntry.hpp

@@ -13,6 +13,7 @@ struct DesktopEntry
     QString icon;
     QString exec;
     QString tryExec;
+    QString startupWmClass;
     QString workingDirectory;
     QStringList categories;
     bool terminal = false;

core/applications/README.md

@@ -2,13 +2,14 @@
 
 Shared C++ service for discovering and launching installed Linux applications from `.desktop` entries.
 
-Desktop and the future Bigscreen shell should both use this library. It has no Desktop-specific QML.
+Desktop and the future Bigscreen shell should both use this library. It has no Desktop-specific QML. Window naming helpers (`displayNameForWindow`, `iconNameForWindow`) are intended for `WindowService`.
 
 ## Behaviour
 
 - Scans XDG application directories (`XDG_DATA_HOME`, `XDG_DATA_DIRS`, with the usual `~/.local/share` and `/usr/share` defaults).
 - Hides entries with `Hidden=true` or `NoDisplay=true`, and respects `OnlyShowIn` / `NotShowIn` / `TryExec`.
 - Exposes a `QAbstractListModel` to QML (`desktopId`, `name`, `genericName`, `comment`, `iconName`, `categories`, `terminal`).
+- Parses `StartupWMClass` and can map a compositor `app_id` / window class to a friendly `Name` (`displayNameForWindow`, `iconNameForWindow`) for `WindowService`.
 - Launches with `QProcess::startDetached` and `QProcess::splitCommand`. Does not use a shell.
 - Strips or substitutes common Exec field codes when launching without files/URLs.