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/hot_reload/src/HotReloadTestDriverNode.cs

@@ -34,6 +34,9 @@ namespace Mods.HotReloadTest
     /// </summary>
     public partial class HotReloadTestDriverNode : Node
     {
+        private int readinessToken = int.MinValue;
+        private ulong readinessStarted;
+        private ulong readinessFrame;
         public const string Flag = "--itest=hot_reload";
 
         private const string LibId = "hot_reload_probe_lib";
@@ -48,7 +51,6 @@ namespace Mods.HotReloadTest
         private int passed;
         private int step;
         private double elapsed;
-        private double stepAt;
         private bool done;
         private GameLaunchArgs startSelection;
         private string modsRoot;
@@ -67,6 +69,7 @@ namespace Mods.HotReloadTest
 
         private void OnReloaded(ModSetReloadedEvent e) => reloads.Add(e);
 
+        /// <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)
@@ -80,9 +83,6 @@ namespace Mods.HotReloadTest
                 return;
             }
 
-            if (elapsed - stepAt < 0.25)
-                return;
-            stepAt = elapsed;
 
             try
             {
@@ -97,8 +97,26 @@ namespace Mods.HotReloadTest
 
         private static bool Busy => GameSession.IsSwitching || ModManager.Instance.IsReloading || ModHotReloadService.IsReloadRunning;
 
+        // 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 void RunStep()
         {
+            if (!WaitForReadyFrames(step, Boot.IsReady && GetTree().CurrentScene != null && !Busy, 120)) return;
             switch (step)
             {
                 case 0: