Add snap layouts shell setting

Expose snapLayoutsEnabled through MobileShellSettings and store it\nin plasmamobilerc.\n\nUse the setting in the Shift snap assist effect eligibility logic\nand add a Convergence KCM switch to control it.\n\nKeep the switch disabled when convergence is off, gaming mode is on,\nor dynamic tiling is enabled so window-placement ownership stays\nconsistent.

components/shellsettingsplugin/mobileshellsettings.cpp

@@ -47,6 +47,7 @@ MobileShellSettings::MobileShellSettings(QObject *parent)
             Q_EMIT gamingModeEnabledChanged();
             Q_EMIT gamingDismissHintEnabledChanged();
             Q_EMIT dynamicTilingEnabledChanged();
+            Q_EMIT snapLayoutsEnabledChanged();
             Q_EMIT allowLogoutChanged();
         }
         if (group.name() == LOCKSCREEN_CONFIG_GROUP) {
@@ -290,6 +291,19 @@ void MobileShellSettings::setDynamicTilingEnabled(bool enabled)
     m_config->sync();
 }
 
+bool MobileShellSettings::snapLayoutsEnabled() const
+{
+    auto group = KConfigGroup{m_config, GENERAL_CONFIG_GROUP};
+    return group.readEntry("snapLayoutsEnabled", true);
+}
+
+void MobileShellSettings::setSnapLayoutsEnabled(bool enabled)
+{
+    auto group = KConfigGroup{m_config, GENERAL_CONFIG_GROUP};
+    group.writeEntry("snapLayoutsEnabled", enabled, KConfigGroup::Notify);
+    m_config->sync();
+}
+
 void MobileShellSettings::updateNavigationBarsInPlasma()
 {
     // Do not update panels when not in Plasma Mobile

components/shellsettingsplugin/mobileshellsettings.h

@@ -60,6 +60,9 @@ class MobileShellSettings : public QObject
     // When false, KWin's native quick-tile behaviour is used unmodified.
     Q_PROPERTY(bool dynamicTilingEnabled READ dynamicTilingEnabled WRITE setDynamicTilingEnabled NOTIFY dynamicTilingEnabledChanged)
 
+    // Snap layout picker — only meaningful in convergence mode when dynamic tiling is off.
+    Q_PROPERTY(bool snapLayoutsEnabled READ snapLayoutsEnabled WRITE setSnapLayoutsEnabled NOTIFY snapLayoutsEnabledChanged)
+
     // logout dialog
     Q_PROPERTY(bool allowLogout READ allowLogout READ allowLogout NOTIFY allowLogoutChanged)
 
@@ -286,6 +289,14 @@ public:
     bool dynamicTilingEnabled() const;
     void setDynamicTilingEnabled(bool enabled);
 
+    /**
+     * Whether the SHIFT snap layout picker is enabled.
+     * Defaults to true; only takes effect in convergence mode when gaming mode
+     * and dynamic tiling are off.
+     */
+    bool snapLayoutsEnabled() const;
+    void setSnapLayoutsEnabled(bool enabled);
+
     /**
      * Whether logout button is shown in the logout/shutdown dialog.
      */
@@ -335,6 +346,7 @@ Q_SIGNALS:
     void gamingModeEnabledChanged();
     void gamingDismissHintEnabledChanged();
     void dynamicTilingEnabledChanged();
+    void snapLayoutsEnabledChanged();
     void allowLogoutChanged();
     void lockscreenLeftButtonActionChanged();
     void lockscreenRightButtonActionChanged();

kcms/mobileshell/ui/main.qml

@@ -95,7 +95,24 @@ KCM.SimpleKCM {
                 }
             }
 
-            FormCard.FormDelegateSeparator { above: dynamicTilingSwitch; below: autoHidePanels }
+            FormCard.FormDelegateSeparator { above: dynamicTilingSwitch; below: snapLayoutsSwitch }
+
+            FormCard.FormSwitchDelegate {
+                id: snapLayoutsSwitch
+                text: i18n("Snap Layouts")
+                description: i18n("Show the snap layout picker from the maximize button. Disabled while convergence mode is off, gaming mode is active, or dynamic tiling is enabled.")
+                enabled: ShellSettings.Settings.convergenceModeEnabled
+                         && !ShellSettings.Settings.gamingModeEnabled
+                         && !ShellSettings.Settings.dynamicTilingEnabled
+                checked: ShellSettings.Settings.snapLayoutsEnabled
+                onCheckedChanged: {
+                    if (checked != ShellSettings.Settings.snapLayoutsEnabled) {
+                        ShellSettings.Settings.snapLayoutsEnabled = checked;
+                    }
+                }
+            }
+
+            FormCard.FormDelegateSeparator { above: snapLayoutsSwitch; below: autoHidePanels }
 
             FormCard.FormSwitchDelegate {
                 id: autoHidePanels

kwin/effects/shift-snap-assist/contents/ui/main.qml

@@ -24,6 +24,7 @@ KWinComponents.SceneEffect {
     readonly property bool snapLayoutsEligible: ShellSettings.Settings.convergenceModeEnabled
                                              && !ShellSettings.Settings.gamingModeEnabled
                                              && !ShellSettings.Settings.dynamicTilingEnabled
+                                             && ShellSettings.Settings.snapLayoutsEnabled
     readonly property int hoverBarHeight: 30
     readonly property int decorationButtonSize: 16
     readonly property int decorationButtonSpacing: 8
@@ -372,6 +373,12 @@ KWinComponents.SceneEffect {
                 effect.hideSnapLayouts();
             }
         }
+
+        function onSnapLayoutsEnabledChanged() {
+            if (!effect.snapLayoutsEligible) {
+                effect.hideSnapLayouts();
+            }
+        }
     }
 
     // ── Gap constant (must match shift-tiling) ────────────────────────────