Keep Settings recovery isolated and display-safe

config/dot/quickshell/settings-system-harness.qml

@@ -9,6 +9,7 @@ ShellRoot {
     id: root
 
     property var resetCalls: []
+    property var appliedBatches: []
     property bool displayBlocked: false
 
     function recordReset(name: string): void {
@@ -18,6 +19,18 @@ ShellRoot {
     }
 
     Component.onCompleted: {
+        // Keep compositor verification entirely inside the isolated harness.
+        // Production applyOptions is covered separately by the Hyprland write
+        // contract; this seam proves commit/reset routing without changing the
+        // desktop that is running the test.
+        SystemSettings.compositorApplyOverride = function(requested) {
+            const batches = root.appliedBatches.slice();
+            batches.push(requested);
+            root.appliedBatches = batches;
+            for (const key in requested)
+                DesktopPreferences.set(key, requested[key]);
+            return true;
+        };
         SystemSettings.displayBusy = function() { return false; };
         SystemSettings.readDisplays = function() { return DesktopPreferences.get("displays"); };
         SystemSettings.protectDisplays = function(value) {
@@ -85,7 +98,15 @@ ShellRoot {
         }
 
         function resetState(): string {
-            return JSON.stringify({ calls: root.resetCalls, displayBlocked: root.displayBlocked });
+            return JSON.stringify({
+                calls: root.resetCalls,
+                displayBlocked: root.displayBlocked,
+                appliedBatches: root.appliedBatches
+            });
+        }
+
+        function applyState(): string {
+            return JSON.stringify(root.appliedBatches);
         }
 
         function panelAllowed(panel: string): bool {