WakewordModel: clean up stale comment, clarify ring-fill boundary case

tests/02-wakeword-cs/WakewordModel.cs

@@ -110,7 +110,11 @@ internal sealed class WakewordModel : IDisposable
             _rawRingFill += copyToFront;
             if (copyToFront < FrameSamples)
             {
-                // Shouldn't happen on the very first call, but defensive.
+                // Boundary case: ring was partially full and the new frame overshoots
+                // remaining capacity. Fires exactly once during warm-up (typically call 2,
+                // when _rawRingFill = 1280 and the incoming 1280 samples overshoot the
+                // remaining 480 capacity). Shift the older samples left to make room,
+                // then write the leftover at the tail.
                 int leftover = FrameSamples - copyToFront;
                 Array.Copy(_rawRing, leftover, _rawRing, 0, MelInputSamples - leftover);
                 Array.Copy(frame1280, copyToFront, _rawRing, MelInputSamples - leftover, leftover);
@@ -191,8 +195,6 @@ internal sealed class WakewordModel : IDisposable
         return clsOut[0, 0];
     }
 
-    // ... methods follow in Step 2 ...
-
     public void Dispose()
     {
         _mel.Dispose();