1 files changed, 12 insertions, 1 deletions
diff --git a/src/chess.h b/src/chess.h
index 137344f..a83a13d 100755
--- a/src/chess.h
+++ b/src/chess.h
@@ -652,7 +652,18 @@ typedef struct _POSITION
     SCORE iMaterialBalance[2];             // material balance
 
     // temporary storage space for use in eval
-    COOR cTrapped[2];
+    //
+    // Small fixed-capacity list of zero-mobility piece candidates per
+    // color (bishop/knight/rook/queen evals each can push one), not
+    // just the single most-recently-evaluated one -- a single COOR
+    // here used to silently let a later piece's candidacy overwrite an
+    // earlier one on the same side, discarding it even if it was a
+    // genuinely trapped (zero mobility + actually attacked) piece.
+    // Capacity of 4 is deliberately generous; if a position somehow
+    // has more than 4 simultaneously zero-mobility non-pawn pieces on
+    // one side, the rest are just dropped, not a real concern.
+    COOR cTrapped[2][4];
+    ULONG uNumTrapped[2];
     ULONG uArmyScaler[2];
     ULONG uClosedScaler;
     SCORE iScore[2];