feat(greeter): support undecided state waiting for DDM decision

src/CMakeLists.txt

@@ -13,6 +13,9 @@ include(${CMAKE_SOURCE_DIR}/cmake/TranslationUtils.cmake)
 find_package(Dtk6 REQUIRED COMPONENTS Core Declarative SystemSettings Tools)
 if (NOT DISABLE_DDM)
     find_package(DDM 0.2.0 REQUIRED COMPONENTS Common)
+    if (DDM_VERSION VERSION_LESS 0.3.8)
+        add_compile_definitions(DDM_VERSION_LT_0_3_8)
+    endif()
 endif()
 find_package(QT NAMES Qt6 COMPONENTS Core REQUIRED)
 find_package(Qt6 CONFIG REQUIRED ShaderTools Concurrent RemoteObjects Network)

src/core/lockscreen.cpp

@@ -36,10 +36,9 @@ LockScreen::LockScreen(ILockScreen *impl, SurfaceContainer *parent, GreeterProxy
 
 void LockScreen::lock()
 {
-    if (isVisible()) {
-        return;
-    }
-
+    // Do not early-return on isVisible(): the greeter may start in the
+    // undecided state (surface visible, not yet locked), so lock() must
+    // still flip the lock state afterwards.
     setVisible(true);
 
     if (!m_greeterProxy->isLocked())

src/greeter/greeterproxy.cpp

@@ -34,9 +34,11 @@
 
 // System
 #include <security/pam_appl.h>
 #include <systemd/sd-login.h>
 #include <pwd.h>
 
+#include <QTimer>
+
 using namespace DDM;
 
 /////////////////////
@@ -120,6 +122,19 @@
     connect(m_socket, &QLocalSocket::readyRead, this, &GreeterProxy::readyRead);
     connect(m_socket, &QLocalSocket::errorOccurred, this, &GreeterProxy::error);
 
+    // Fallback: if DDM never decides (ShowGreeter / UserActivateMessage), show
+    // the greeter after a grace period instead of staying on the wallpaper.
+    m_undecidedTimer = new QTimer(this);
+    m_undecidedTimer->setSingleShot(true);
+    m_undecidedTimer->setInterval(5000);
+    connect(m_undecidedTimer, &QTimer::timeout, this, [this] {
+        if (m_undecided) {
+            qCWarning(lcTlGreeter) << "DDM did not decide in time, showing greeter by fallback";
+            lock();
+        }
+    });
+    m_undecidedTimer->start();
+
     conn.connect(Logind::serviceName(),
                  Logind::managerPath(),
                  Logind::managerIfaceName(),
@@ -159,6 +174,11 @@
 {
     if (isLocked && !m_isLocked) {
         m_isLocked = true;
+        if (m_undecided) {
+            m_undecided = false;
+            m_undecidedTimer->stop();
+            Q_EMIT undecidedChanged(false);
+        }
         if (m_lockScreen && !m_lockScreen->isVisible())
             m_lockScreen->lock();
         Q_EMIT lockChanged(true);
@@ -290,7 +310,7 @@
         return;
     }
 
-    if (strcmp(service, "ddm") == 0) {
+    if (strncmp(service, "ddm", 3) == 0) {
         QString user = QString::fromLocal8Bit(username);
         qCInfo(lcTlGreeter) << "New session added: id=" << id << ", user=" << user;
         userModel()->updateUserLoginState(user, true);
@@ -496,6 +516,14 @@
             qCInfo(lcTlGreeter) << "switch to greeter";
             lock();
         } break;
+#ifndef DDM_VERSION_LT_0_3_8
+        case DaemonMessages::ShowGreeter: {
+            qCInfo(lcTlGreeter) << "show greeter";
+            // Full lock screen transition (LockScreen mode, hidden workspace),
+            // matching the previous startup behavior of showLockScreen().
+            Helper::instance()->showLockScreen(false);
+        } break;
+#endif
         case DaemonMessages::UserActivateMessage: {
             QString user;
             int sessionId;
@@ -512,6 +540,23 @@
                 break;
 
             qCInfo(lcTlGreeter) << "activate successfully: " << user << ", XDG_SESSION_ID: " << sessionId;
+
+            // DDM drives the direct login (autologin / unlock), so the greeter
+            // must hide unconditionally. onSessionNew's setLock(false) may never
+            // fire (currentUserName mismatch / session service not "ddm"). When
+            // still in the undecided state, the lock screen surface is visible
+            // (wallpaper) but not locked, so setLock(false) alone would no-op:
+            // restore the desktop mode and hide the surface explicitly.
+            if (m_undecided) {
+                m_undecided = false;
+                m_undecidedTimer->stop();
+                Q_EMIT undecidedChanged(false);
+            }
+            if (m_lockScreen && m_lockScreen->isVisible()) {
+                Q_EMIT m_lockScreen->unlock();
+                m_lockScreen->setVisible(false);
+            }
+            setLock(false);
         } break;
         case DaemonMessages::UserLoggedIn: {
             QString user;

src/greeter/greeterproxy.h

@@ -6,9 +6,10 @@
 #include "QDBusContext"
 #include <QDBusObjectPath>
 #include <QObject>
 #include <QQmlEngine>
 
 class QLocalSocket;
+class QTimer;
 
 class LockScreen;
 
@@ -34,6 +35,7 @@
     Q_PROPERTY(bool    canHybridSleep   READ canHybridSleep   NOTIFY canHybridSleepChanged)
 
     Q_PROPERTY(bool    isLocked         READ isLocked         NOTIFY lockChanged)
+    Q_PROPERTY(bool    undecided        READ undecided        NOTIFY undecidedChanged)
     Q_PROPERTY(int     failedAttempts   READ failedAttempts   NOTIFY failedAttemptsChanged)
     Q_PROPERTY(bool    showShutdownView READ showShutdownView WRITE  setShowShutdownView NOTIFY showShutdownViewChanged)
     Q_PROPERTY(bool    showAnimation    READ showAnimation    NOTIFY showAnimationChanged)
@@ -91,6 +93,16 @@
      */
     inline bool isLocked()         const { return m_isLocked;         };
 
+    /**
+     * @brief Get whether DDM has not decided yet whether to show the greeter
+     * or to log in directly. The greeter surface (wallpaper) is shown but the
+     * login UI stays hidden until DDM sends ShowGreeter / UserActivateMessage,
+     * or the fallback timer fires.
+     *
+     * @return true if DDM has not decided yet
+     */
+    inline bool undecided()        const { return m_undecided;        };
+
     /**
      * @brief Get the number of failed login attempts (password incorrect)
      * The value is reset to 0 when unlocked successfully
@@ -275,6 +287,9 @@
     /** @brief Emitted when lock state changes. See isLocked() */
     void lockChanged             (bool isLocked);
 
+    /** @brief Emitted when undecided state changes. See undecided() */
+    void undecidedChanged        (bool undecided);
+
     /** @brief Emitted when failed attempts changes. See failedAttempts() */
     void failedAttemptsChanged   (int failedAttempts);
 
@@ -324,6 +339,8 @@
     bool m_canHybridSleep   { false };
 
     bool m_isLocked         { false };
+    bool m_undecided        { true  };
+    QTimer *m_undecidedTimer{ nullptr };
     int  m_failedAttempts   { 0     };
     bool m_showShutdownView { false };
     bool m_showAnimation    { true  };

src/greeter/usermodel.cpp

@@ -138,6 +138,15 @@ int UserModel::rowCount(const QModelIndex &parent) const
 
 void UserModel::updateUserLoginState(const QString &username, bool loggedIn)
 {
+    // TODO: May remove once UserModel is guaranteed to resolve every loggable
+    // user (consider whether users not manually added can still log in directly).
+    if (loggedIn && !getUser(username)) {
+        if (!tryAddNssUser(username)) {
+            qCWarning(lcTlGreeter) << "User" << username << "not found when updating login state";
+            return;
+        }
+    }
+
     auto user = std::find_if(d->users.begin(), d->users.end(), [&username](const UserPtr &user) {
         return user->userName() == username;
     });

src/plugins/lockscreen/qml/Greeter.qml

@@ -39,7 +39,7 @@ FocusScope {
         color: 'black'
         opacity: 0.0
         transformOrigin: Item.Center
-        state: (GreeterProxy.isLocked || GreeterProxy.showShutdownView) ? "Show" : "Hide"
+        state: (GreeterProxy.isLocked || GreeterProxy.undecided || GreeterProxy.showShutdownView) ? "Show" : "Hide"
         states: [
             State {
                 name: "Show"