fix: 根除flaky测试层三bug

Root cause chain (逐层发现):
1. 非庄家第一轮: 南碰了自己的弃牌→不摸牌→Deck.Count=55≠54
   → 修复: 测试接受54|55两情况
2. wildcard静态污染: Wuhan→ConfigureWildcards([35])泄漏到CoreTests
   → 十三幺手牌含红中(35)→IsWildcard=true→跳过→13张守卫拒绝
   → 修复: CoreTests构造时ConfigureWildcards([])清零
3. Random.Shared非确定性: 牌库洗牌用共享Random→跨run不可复现
   → 修复: MahjongRoom(seed:)参数→测试seed:42确定性

附加:
- AssemblyInfo.cs: 关闭xUnit并行(静态状态竞态)
- 补'碰碰和'到FanValue fallback switch(国标名称)

Test: 20/20 all green, first time since project creation

RuleEngine.Tests/AssemblyInfo.cs

@@ -0,0 +1,4 @@
+// Disable test parallelism: static state (ConfigureWildcards) leaks between test classes
+using Xunit;
+
+[assembly: CollectionBehavior(DisableTestParallelization = true)]

RuleEngine.Tests/CoreTests.cs

@@ -84,6 +84,12 @@ public class MeldsSolverTests
 {
     private readonly MeldsSolver _solver = new(new Dictionary<string, FanConfig>());
 
+    public MeldsSolverTests()
+    {
+        // Reset wildcards to avoid contamination from integration tests
+        MahjongTile.ConfigureWildcards([]);
+    }
+
     // === 标准胡牌 ===
     [Fact]
     public void 标准胡_4面子1对_ShouldWin()

RuleEngine.Tests/MahjongRoomIntegrationTests.cs

@@ -35,7 +35,7 @@ public class MahjongRoomIntegrationTests
     public void 发牌_四川_庄14闲13_牌墙55()
     {
         var rules = LoadDsl("xuezhandaodi");
-        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" });
+        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" }, seed: 42);
         room.Deal();
 
         Assert.Equal(14, room.State.Hands["东"].Count);
@@ -51,7 +51,7 @@ public class MahjongRoomIntegrationTests
     public void 发牌_武汉_牌库正确()
     {
         var rules = LoadDsl("wuhan");
-        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" });
+        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" }, seed: 42);
         room.Deal();
 
         int totalTiles = room.State.Hands.Sum(h => h.Value.Count) + room.State.Deck.Count;
@@ -64,7 +64,7 @@ public class MahjongRoomIntegrationTests
     public void 庄家第一轮不摸牌_直接出牌()
     {
         var rules = LoadDsl("xuezhandaodi");
-        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" });
+        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" }, seed: 42);
         room.Deal();
 
         Assert.Equal(14, room.State.Hands["东"].Count);
@@ -83,7 +83,7 @@ public class MahjongRoomIntegrationTests
     public void 非庄家第一轮_摸牌后出牌()
     {
         var rules = LoadDsl("xuezhandaodi");
-        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" });
+        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" }, seed: 42);
         room.Deal();
 
         // Clear西/北hands to prevent pung reactions that steal the turn
@@ -103,8 +103,9 @@ public class MahjongRoomIntegrationTests
 
         // Hand may have changed due to pung/chi reactions; should be 10-13
         Assert.InRange(room.State.Hands["南"].Count, 7, 13);
-        Assert.Equal(54, room.State.Deck.Count);
+        // Deck may be 54 (drawn) or 55 (南 punged on 东's discard → no draw)
-        Assert.Contains(evt2, e => e.Type == "draw");
+        Assert.Contains(room.State.Deck.Count, new[] { 54, 55 });
+        Assert.Contains(evt2, e => e.Type == "draw" || e.Type == "pung");
         Assert.Contains(evt2, e => e.Type == "discard");
     }
 
@@ -113,7 +114,7 @@ public class MahjongRoomIntegrationTests
     public void 回合之后_手牌总数保持恒定()
     {
         var rules = LoadDsl("xuezhandaodi");
-        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" });
+        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" }, seed: 42);
         room.Deal();
 
         int totalBefore = room.State.Hands.Sum(h => h.Value.Count)
@@ -137,7 +138,7 @@ public class MahjongRoomIntegrationTests
     public void 完整一局_四川血战_不出错()
     {
         var rules = LoadDsl("xuezhandaodi");
-        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" });
+        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" }, seed: 42);
         room.Run();
 
         Assert.True(room.IsFinished);
@@ -152,7 +153,7 @@ public class MahjongRoomIntegrationTests
     public void 完整一局_武汉_不出错()
     {
         var rules = LoadDsl("wuhan");
-        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" });
+        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" }, seed: 42);
         room.Run();
         Assert.True(room.IsFinished);
         Assert.Equal(0, room.State.Scores.Values.Sum());
@@ -162,7 +163,7 @@ public class MahjongRoomIntegrationTests
     public void 完整一局_国标_不出错()
     {
         var rules = LoadDsl("guobiao");
-        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" });
+        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" }, seed: 42);
         room.Run();
 
         Assert.True(room.IsFinished);
@@ -173,7 +174,7 @@ public class MahjongRoomIntegrationTests
     public void 完整一局_广东鸡平胡_不出错()
     {
         var rules = LoadDsl("guangdong_jipinghu");
-        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" });
+        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" }, seed: 42);
         room.Run();
 
         Assert.True(room.IsFinished);
@@ -185,7 +186,7 @@ public class MahjongRoomIntegrationTests
     public void 构造听牌_副露后自摸()
     {
         var rules = LoadDsl("xuezhandaodi");
-        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" });
+        var room = new MahjongRoom(rules, new[] { "东", "南", "西", "北" }, seed: 42);
         room.Deal();
 
         // 东 already pung-ed 1万: exposed has {1,1,1}

RuleEngine/MahjongRoom.cs

@@ -18,13 +18,14 @@ public class MahjongRoom
     private readonly MahjongPhaseMachine _phaseMachine;
     private readonly MahjongScoreEngine _scoreEngine;
     private readonly bool _autoMode;
-    private readonly Random _rng = Random.Shared;
+    private readonly Random _rng;
 
     public MahjongRoom(MahjongDslRoot rules, string[] playerNames, bool autoMode = false,
-        string? humanPlayer = null)
+        string? humanPlayer = null, int? seed = null)
     {
         _rules = rules;
         _autoMode = autoMode;
+        _rng = seed.HasValue ? new Random(seed.Value) : Random.Shared;
         _ais = playerNames.Select((n, i) => new RandomMahjongAI(n, new Random(i * 7919))).ToList();
 
         var fanConfig = BuildFanConfig();