1 files changed, 13 insertions, 0 deletions
diff --git a/src/chess.h b/src/chess.h
index 305c681..421667f 100755
--- a/src/chess.h
+++ b/src/chess.h
@@ -739,6 +739,19 @@ typedef struct _POSITION
     // see _IsSquareXrayedByMinor.
     BITBOARD bbMinorXrayAttacks[2];
 
+    // Rook's turn to convert (board_representation/EVAL.md section
+    // 9, 2026-09-05): "which squares does this side's rook(s) attack,"
+    // ORed in via _RookAttacksBB(c, pos->bbOccupied) straight from
+    // _EvalRook's mobility computation, same Eval()-scoped/cleared-
+    // per-call lifetime as bbMinorAttacks. bbRookXrayAttacks mirrors
+    // bbMinorXrayAttacks: squares seen past a friendly rook/queen
+    // battery partner or an x-rayable enemy queen/king, single-hop
+    // only (same deliberate simplification bishop already made, see
+    // _EvalRook's mobility comment). Queen/king haven't converted yet
+    // and still write their own bits into the old bvAttacks structure.
+    BITBOARD bbRookAttacks[2];
+    BITBOARD bbRookXrayAttacks[2];
+
     ULONG uWhiteSqBishopCount[2];          // num bishops on white squares
     SCORE iMaterialBalance[2];             // material balance