test: replace fixed waits with observable GUI readiness

Advance integration drivers only after their requested controls, game state or file effects are observable. Preserve the behavioral assertions and shared viewport capture pipeline.

test_suites/display_settings/src/DisplaySettingsTestDriverNode.cs

@@ -24,6 +24,9 @@ namespace Mods.DisplaySettingsTest
     /// </summary>
     public partial class DisplaySettingsTestDriverNode : Node
     {
+        private int readinessToken = int.MinValue;
+        private ulong readinessStarted;
+        private ulong readinessFrame;
         private const string Display = "Window/Column/Body/Pages/Display/";
         private const float TimeoutSeconds = 60f;
         private const string ResetButton = "Window/Column/Footer/Row/ResetButton";
@@ -38,7 +41,6 @@ namespace Mods.DisplaySettingsTest
         private int step;
         private int shotTab;
         private double elapsed;
-        private double stepAt;
         private bool done;
 
         public DisplaySettingsTestDriverNode(string shotsDir)
@@ -47,6 +49,7 @@ namespace Mods.DisplaySettingsTest
             backup = File.Exists(settingsPath) ? File.ReadAllText(settingsPath) : null;
         }
 
+        /// <summary>Advances when observable scene/UI readiness has held for two real frames; the watchdog remains active.</summary>
         public override void _Process(double delta)
         {
             if (done)
@@ -60,9 +63,6 @@ namespace Mods.DisplaySettingsTest
                 return;
             }
 
-            if (elapsed - stepAt < 0.5)
-                return;
-            stepAt = elapsed;
 
             try
             {
@@ -75,8 +75,39 @@ namespace Mods.DisplaySettingsTest
             }
         }
 
+        // Deferred UI/scene work must finish before the original assertions run.
+        private bool WaitForReadyFrames(int token, bool ready, double timeoutSeconds = 30)
+        {
+            var now = global::Godot.Time.GetTicksMsec();
+            if (readinessToken != token)
+            {
+                readinessToken = token;
+                readinessStarted = now;
+                readinessFrame = 0;
+            }
+            if (now - readinessStarted > timeoutSeconds * 1000)
+                throw new global::System.TimeoutException($"readiness at step {token}: scene/UI did not become ready");
+            if (!ready) { readinessFrame = 0; return false; }
+            if (readinessFrame == 0) readinessFrame = global::Godot.Engine.GetProcessFrames();
+            return global::Godot.Engine.GetProcessFrames() - readinessFrame >= 2;
+        }
+
+        private bool DisplayReady()
+        {
+            if (step == 0) return true;
+            if (menu == null || !menu.Visible) return false;
+            return step switch
+            {
+                2 => DisplayServer.WindowGetMode() == DisplayServer.WindowMode.Windowed && DisplayServer.WindowGetSize() == WindowSize,
+                3 or 6 => DisplayServer.WindowGetMode() == DisplayServer.WindowMode.Fullscreen,
+                5 => DisplayServer.WindowGetMode() == DisplayServer.WindowMode.Windowed,
+                _ => true
+            };
+        }
+
         private void RunStep()
         {
+            if (!WaitForReadyFrames(step * 10 + shotTab, Boot.IsReady && GetTree().CurrentScene != null && DisplayReady(), 30)) return;
             switch (step)
             {
                 case 0: