feat: 吃(chi)反应支持 — HandleDiscardReactions + 人类/AI

- CanChi→CanChiCheck公开给MahjongRoom调用
- HandleDiscardReactions: offset=1(上家)且非字牌时检查chi
- 人类HUD: c(吃)选项
- ExecuteChi: 找到配对的两张牌→创建chi副露→出牌
- ExecutePungKongHuman: 抽取碰/杠人类交互逻辑

RuleEngine/MahjongRoom.cs

@@ -281,6 +281,11 @@ public class MahjongRoom
 
             int sameCount = State.Hands[p].Count(t => t == discardTile);
             bool canWin = false, canKong = sameCount >= 3, canPung = sameCount >= 2;
+            bool canChi = false;
+
+            // Chi: only available to the player immediately after the discarder (上家)
+            if (offset == 1 && !MahjongTile.IsHonor(discardTile))
+                canChi = _phaseMachine.CanChiCheck(State, p, discardTile);
 
             // Check win
             var fullHand = FullHand(State, p, extraTile: discardTile);
@@ -292,7 +297,7 @@ public class MahjongRoom
                 canWin = true;
 
             // Human player: ask what they want to do
-            if (_human != null && p == _human.Name && (canWin || canKong || canPung))
+            if (_human != null && p == _human.Name && (canWin || canKong || canPung || canChi))
             {
                 Console.WriteLine();
                 Console.WriteLine($"=== {p} 可以反应 ===");
@@ -303,6 +308,7 @@ public class MahjongRoom
                 if (canWin) ops.Add("h(胡)");
                 if (canKong) ops.Add("k(杠)");
                 if (canPung) ops.Add("p(碰)");
+                if (canChi) ops.Add("c(吃)");
                 ops.Add("Enter(过)");
                 Console.WriteLine(string.Join(" ", ops));
                 Console.Write("> ");
@@ -326,42 +332,11 @@ public class MahjongRoom
                 if ((input == "k" && canKong) || (input == "p" && canPung))
                 {
                     string action = input == "k" ? "ming_kong" : "pung";
-                    int toRemove = action == "ming_kong" ? 3 : 2;
+                    return ExecutePungKongHuman(p, discardTile, action);
-                    for (int r = 0; r < toRemove; r++)
+                }
-                        State.Hands[p].Remove(discardTile);
+                if (input == "c" && canChi)
-
+                {
-                    State.DiscardPool.Remove(discardTile);
+                    return ExecuteChi(p, discardTile);
-                    int meldSize = action == "ming_kong" ? 4 : 3;
-                    State.Exposed[p].Add(new Meld
-                    {
-                        Type = action,
-                        Tiles = Enumerable.Repeat(discardTile, meldSize).ToList(),
-                        SourcePlayer = discarder
-                    });
-                    State.CurrentPlayer = p;
-                    State.LastDiscard = null;
-                    State.LastDiscardPlayer = null;
-                    State.AddEvent(action, p, discardTile,
-                        action == "pung" ? "碰！" : "明杠！");
-
-                    // Human must discard after pung/kong
-                    var hand = State.Hands[p];
-                    Console.WriteLine($"  碰/杠后手牌 ({hand.Count}张):");
-                    var sorted = hand.OrderBy(t => t).ToList();
-                    for (int i = 0; i < sorted.Count; i++)
-                        Console.WriteLine($"    [{i + 1}] {MahjongTile.ToString(sorted[i])}");
-                    Console.Write("  请出牌 (1-{0}): ".Replace("{0}", hand.Count.ToString()), hand.Count);
-                    int discardIdx;
-                    while (!int.TryParse(Console.ReadLine(), out discardIdx) || discardIdx < 1 || discardIdx > sorted.Count)
-                        Console.Write("  无效，重试: ");
-                    int tileToDiscard = sorted[discardIdx - 1];
-                    State.Hands[p].Remove(tileToDiscard);
-                    State.LastDiscard = tileToDiscard;
-                    State.LastDiscardPlayer = p;
-                    RecordDiscard(p, tileToDiscard);
-                    State.AddEvent("discard", p, tileToDiscard,
-                        $"出牌: {MahjongTile.ToString(tileToDiscard)}");
-                    return true;
                 }
                 // Human passed — continue to next player
                 continue;
@@ -375,6 +350,106 @@ public class MahjongRoom
         return false;
     }
 
+    private bool ExecutePungKongHuman(string p, int discardTile, string action)
+    {
+        string discarder = State.LastDiscardPlayer ?? "";
+        State.DiscardPool.Remove(discardTile);
+        int toRemove = action == "ming_kong" ? 3 : 2;
+        for (int r = 0; r < toRemove; r++)
+            State.Hands[p].Remove(discardTile);
+        int meldSize = action == "ming_kong" ? 4 : 3;
+        State.Exposed[p].Add(new Meld
+        {
+            Type = action,
+            Tiles = Enumerable.Repeat(discardTile, meldSize).ToList(),
+            SourcePlayer = discarder
+        });
+        State.CurrentPlayer = p;
+        State.LastDiscard = null;
+        State.LastDiscardPlayer = null;
+        State.AddEvent(action, p, discardTile, action == "pung" ? "碰！" : "明杠！");
+
+        var hand = State.Hands[p];
+        Console.WriteLine($"  碰/杠后手牌 ({hand.Count}张):");
+        var sorted = hand.OrderBy(t => t).ToList();
+        for (int i = 0; i < sorted.Count; i++)
+            Console.WriteLine($"    [{i + 1}] {MahjongTile.ToString(sorted[i])}");
+        Console.Write($"  请出牌 (1-{hand.Count}): ");
+        int discardIdx;
+        while (!int.TryParse(Console.ReadLine(), out discardIdx) || discardIdx < 1 || discardIdx > sorted.Count)
+            Console.Write("  无效，重试: ");
+        int tileToDiscard = sorted[discardIdx - 1];
+        State.Hands[p].Remove(tileToDiscard);
+        State.LastDiscard = tileToDiscard;
+        State.LastDiscardPlayer = p;
+        RecordDiscard(p, tileToDiscard);
+        State.AddEvent("discard", p, tileToDiscard, $"出牌: {MahjongTile.ToString(tileToDiscard)}");
+        return true;
+    }
+
+    private bool ExecuteChi(string p, int discardTile)
+    {
+        string discarder = State.LastDiscardPlayer ?? "";
+        State.DiscardPool.Remove(discardTile);
+
+        int suit = MahjongTile.Suit(discardTile);
+        int rank = MahjongTile.Rank(discardTile);
+        var hand = State.Hands[p];
+
+        // Find which two tiles form the chi sequence
+        List<int> toRemove = new();
+        if (rank >= 3 && hand.Any(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank - 2)
+            && hand.Any(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank - 1))
+        {
+            toRemove.Add(hand.First(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank - 2));
+            toRemove.Add(hand.First(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank - 1));
+        }
+        else if (rank >= 2 && rank <= 8 && hand.Any(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank - 1)
+            && hand.Any(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank + 1))
+        {
+            toRemove.Add(hand.First(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank - 1));
+            toRemove.Add(hand.First(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank + 1));
+        }
+        else if (rank <= 7 && hand.Any(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank + 1)
+            && hand.Any(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank + 2))
+        {
+            toRemove.Add(hand.First(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank + 1));
+            toRemove.Add(hand.First(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank + 2));
+        }
+        foreach (var t in toRemove) State.Hands[p].Remove(t);
+
+        var chiTiles = new List<int>(toRemove) { discardTile };
+        chiTiles.Sort();
+        State.Exposed[p].Add(new Meld
+        {
+            Type = "chi",
+            Tiles = chiTiles,
+            SourcePlayer = discarder
+        });
+        State.CurrentPlayer = p;
+        State.LastDiscard = null;
+        State.LastDiscardPlayer = null;
+        State.AddEvent("chi", p, discardTile, $"吃！{string.Join(",", chiTiles.Select(MahjongTile.ToString))}");
+
+        // Human must discard after chi
+        var remainingHand = State.Hands[p];
+        Console.WriteLine($"  吃后手牌 ({remainingHand.Count}张):");
+        var sorted = remainingHand.OrderBy(t => t).ToList();
+        for (int i = 0; i < sorted.Count; i++)
+            Console.WriteLine($"    [{i + 1}] {MahjongTile.ToString(sorted[i])}");
+        Console.Write($"  请出牌 (1-{remainingHand.Count}): ");
+        int discardIdx;
+        while (!int.TryParse(Console.ReadLine(), out discardIdx) || discardIdx < 1 || discardIdx > sorted.Count)
+            Console.Write("  无效，重试: ");
+        int tileToDiscard = sorted[discardIdx - 1];
+        State.Hands[p].Remove(tileToDiscard);
+        State.LastDiscard = tileToDiscard;
+        State.LastDiscardPlayer = p;
+        RecordDiscard(p, tileToDiscard);
+        State.AddEvent("discard", p, tileToDiscard, $"出牌: {MahjongTile.ToString(tileToDiscard)}");
+        return true;
+    }
+
     private bool ExecuteWinClaim(string player, int discardTile, MeldsResult winResult)
     {
         State.DiscardPool.Remove(discardTile);

RuleEngine/Phase/PhaseMachine.cs

@@ -99,7 +99,7 @@ public class MahjongPhaseMachine
         // Chi
         if (state.LastDiscard.HasValue && state.LastDiscardPlayer != playerId)
         {
-            if (CanChi(state, playerId, state.LastDiscard.Value))
+            if (CanChiCheck(state, playerId, state.LastDiscard.Value))
                 actions.Add(new ActionOption { Action = "chi", Priority = 1 });
         }
 
@@ -147,7 +147,7 @@ public class MahjongPhaseMachine
             state.Hands[playerId].Contains(m.Tiles[0]));
     }
 
-    private bool CanChi(MahjongGameState state, string playerId, int tile)
+    public bool CanChiCheck(MahjongGameState state, string playerId, int tile)
     {
         if (MahjongTile.IsHonor(tile)) return false;
         int suit = MahjongTile.Suit(tile);