🐛 Don't search with fixed depth when cutechess provides 0s to move

src/Lynx/Engine.cs

@@ -155,21 +155,28 @@ public SearchResult BestMove(GoCommand goCommand)
             millisecondsIncrement = goCommand.BlackIncrement;
         }
 
-        if (millisecondsLeft != 0)  // Cutechess sometimes sends negative wtime/btime
+        if (goCommand.WhiteTime != 0 || goCommand.BlackTime != 0)  // Cutechess sometimes sends negative wtime/btime
         {
+            const int minSearchTime = 50;
+
             if (goCommand.MovesToGo == default)
             {
                 // Inspired by Alexandria: time overhead to avoid timing out in the engine-gui communication process
-                millisecondsLeft -= 50;
-                millisecondsLeft = Math.Clamp(millisecondsLeft, 50, int.MaxValue); // Avoiding 0/negative values
+                const int engineGuiCommunicationTimeOverhead = 50;
+
+                millisecondsLeft -= engineGuiCommunicationTimeOverhead;
+                millisecondsLeft = Math.Clamp(millisecondsLeft, minSearchTime, int.MaxValue); // Avoiding 0/negative values
 
                 // 1/30, suggested by Serdra (EP discord)
                 decisionTime = Convert.ToInt32(Math.Min(0.5 * millisecondsLeft, (millisecondsLeft * 0.03333) + millisecondsIncrement));
             }
             else
             {
-                millisecondsLeft -= 500;
-                millisecondsLeft = Math.Clamp(millisecondsLeft, 50, int.MaxValue); // Avoiding 0/negative values
+                // I prefer to leave some 'just in case' time apart to avoid losing in the last move before the control
+                const int movesToGoTimeOverhead = 500;
+
+                millisecondsLeft -= movesToGoTimeOverhead;
+                millisecondsLeft = Math.Clamp(millisecondsLeft, minSearchTime, int.MaxValue); // Avoiding 0/negative values
 
                 decisionTime = Convert.ToInt32((millisecondsLeft / goCommand.MovesToGo) + millisecondsIncrement);
             }