Pace ADV message skip by engine ticks

engine/Age.Engine.Tests/HotspotInputTests.cs

@@ -81,6 +81,15 @@ public class HotspotInputTests
         }
     }
 
+    private sealed class MessageSkipCadenceHost : RecordingHost
+    {
+        public int ActiveSkipYields;
+        public override void FrameYield()
+        {
+            if (MessageSkip) ActiveSkipYields++;
+        }
+    }
+
     [Fact]
     public void ArmedHotspot_DispatchesHoverAndConsumesActivationWithoutAdvancingPage()
     {
@@ -269,6 +278,25 @@ public class HotspotInputTests
         Assert.Contains(true, host.MessageSkipChanges);
     }
 
+    [Fact]
+    public void MessageSkipState_ReachesHostBeforeFollowingOpcodeCadenceYields()
+    {
+        var table = OpcodeTableJson.Load(Paths.OpcodesJson);
+        var script = ScriptAssembler.Assemble(table, "MESSAGE_SKIP_CADENCE", new List<(int, Operand[])>
+        {
+            (0x88, new[] { I(1) }),
+            (0x55, new[] { G(0x150), I(1) }),
+            (0x55, new[] { G(0x151), I(1) }),
+            (0x88, new[] { I(0) }),
+            (0x2, Array.Empty<Operand>()),
+        }, Array.Empty<string>());
+        var host = new MessageSkipCadenceHost();
+
+        new VirtualMachine(script, table, host).Run();
+
+        Assert.Equal(3, host.ActiveSkipYields);
+    }
+
     private static Operand I(long value) => new(0, value);
     private static Operand G(long address) => new(3, address);
 }

engine/Age.Engine.Tests/TestSupport.cs

@@ -41,7 +41,7 @@ internal class RecordingHost : IHost
         => WaitForInput(layoutSlot, serviceInputCallback);
     public void InputCallbackCompleted(GfxState gfx) => InputCallbackFrames++;
     public void Sleep(long duration) => SleptDurations.Add(duration);
-    public void FrameYield() { }
+    public virtual void FrameYield() { }
     public bool IsMessageSkipActive => MessageSkip;
     public void SetMessageSkipActive(bool active)
     {