Add check extention

src/search/negamax.rs

@@ -16,7 +16,7 @@ pub fn negamax(
     game: &mut Game,
     mut alpha: i32,
     beta: i32,
-    depth: u8,
+    mut depth: u8,
     plies: u8,
     time: &TimeInfo,
     nodes: &mut u64,
@@ -29,13 +29,19 @@ pub fn negamax(
         return Ok(0);
     }
 
+    let color = game.current_player();
+    let in_check = game.board.king_under_check(color);
+
+    if in_check {
+        depth += 1;
+    }
+
     if depth == 0 {
         let q_score = quiescence(game, alpha, beta, time, nodes).map_err(|e| anyhow!("{e}"))?;
         return Ok(q_score);
     }
 
     let mut legal_moves = 0;
-    let color = game.current_player();
     let mut best_score = MIN_SCORE;
     let mut best_move = None;
     let mut moves = game.board.pseudo_moves_all();
@@ -101,7 +107,7 @@ pub fn negamax(
     }
 
     if legal_moves == 0 {
-        if game.board.king_under_check(color) {
+        if in_check {
             return Ok(-MATE_SCORE + plies as i32);
         }
         return Ok(0);