feat(enemy): 选招器支持防重复折扣——WeightedRandomAntiRepeat

上一次选中的招按 EnemyStatsSO.attackAntiRepeatFactor 折扣权重（默认 0.3）。
折扣把唯一候选压到 0 时退化为 Priority 路径，不会出现敌人永不出手。
阶段切换清空防重复记忆。取代 BossBase.UseBossSkillWeighted 里的同名逻辑。

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Assets/_Game/Scripts/Enemies/Abilities/AttackSelectionMode.cs

@@ -3,7 +3,8 @@ namespace BaseGames.Enemies.Abilities
     /// <summary>多攻击选招策略。</summary>
     public enum AttackSelectionMode
     {
-        WeightedRandom, // 合格集内按 weight 加权随机
-        Priority        // 合格集内取 priority 最高（并列取首个）
+        WeightedRandom,           // 合格集内按 weight 加权随机
+        Priority,                 // 合格集内取 priority 最高（并列取首个）
+        WeightedRandomAntiRepeat, // 同 WeightedRandom，但对上一次选中的招施加权重折扣，压低连续重复
     }
 }

Assets/_Game/Scripts/Enemies/Abilities/EnemyAttackSelector.cs

@@ -12,15 +12,26 @@ namespace BaseGames.Enemies.Abilities
         private readonly List<IAttackCandidate> _candidates;
         // 权重缓冲区（与 _candidates 等长，每次选招复用）：避免每次选招 new List 造成 GC
         private readonly List<float> _weightBuf;
+        // 防重复折扣系数：0 = 有替代时绝不连续重复，1 = 不惩罚
+        private readonly float _antiRepeatFactor;
 
-        public EnemyAttackSelector(IEnumerable<IAttackCandidate> candidates)
+        private IAttackCandidate _lastPicked;
+
+        public EnemyAttackSelector(IEnumerable<IAttackCandidate> candidates, float antiRepeatFactor = 0.3f)
         {
-            _candidates = new List<IAttackCandidate>(candidates);
-            _weightBuf  = new List<float>(_candidates.Count);
+            _candidates       = new List<IAttackCandidate>(candidates);
+            _weightBuf        = new List<float>(_candidates.Count);
+            _antiRepeatFactor = Mathf.Clamp01(antiRepeatFactor);
         }
 
         public int Count => _candidates.Count;
 
+        /// <summary>上一次实际选中的招（防重复折扣的作用对象；供测试与调试面板读取）。</summary>
+        public IAttackCandidate LastPicked => _lastPicked;
+
+        /// <summary>对象池复用 / 阶段切换时清除防重复记忆。</summary>
+        public void ResetRepeatMemory() => _lastPicked = null;
+
         private static bool Eligible(IAttackCandidate c, bool hasLOS, bool grounded)
             => c != null && c.CanUse && c.InAttackRange()
                && (!c.RequiresLineOfSight || hasLOS)
@@ -34,9 +45,24 @@ namespace BaseGames.Enemies.Abilities
         }
 
         public IAttackCandidate Select(bool hasLOS, bool grounded, AttackSelectionMode mode)
-            => mode == AttackSelectionMode.Priority
-                ? SelectByPriority(hasLOS, grounded)
-                : SelectByWeight(hasLOS, grounded);
+        {
+            switch (mode)
+            {
+                case AttackSelectionMode.Priority:
+                    return Remember(SelectByPriority(hasLOS, grounded));
+                case AttackSelectionMode.WeightedRandomAntiRepeat:
+                    return Remember(SelectByWeight(hasLOS, grounded, antiRepeat: true));
+                default:
+                    return Remember(SelectByWeight(hasLOS, grounded, antiRepeat: false));
+            }
+        }
+
+        // 只在真选中了东西时更新记忆：选空时保留上一招，避免"空一帧就清掉防重复"。
+        private IAttackCandidate Remember(IAttackCandidate pick)
+        {
+            if (pick != null) _lastPicked = pick;
+            return pick;
+        }
 
         private IAttackCandidate SelectByPriority(bool hasLOS, bool grounded)
         {
@@ -50,20 +76,25 @@ namespace BaseGames.Enemies.Abilities
             return best;
         }
 
-        private IAttackCandidate SelectByWeight(bool hasLOS, bool grounded)
+        private IAttackCandidate SelectByWeight(bool hasLOS, bool grounded, bool antiRepeat)
         {
             // 有效权重：不合格候选填 0（由共享原语保证零权重项绝不被选中）。缓冲区复用 → 选招零 GC。
             _weightBuf.Clear();
             for (int i = 0; i < _candidates.Count; i++)
             {
                 var c = _candidates[i];
-                _weightBuf.Add(Eligible(c, hasLOS, grounded) ? Mathf.Max(0f, c.Weight) : 0f);
+                float w = Eligible(c, hasLOS, grounded) ? Mathf.Max(0f, c.Weight) : 0f;
+                // 防重复：上一招权重打折。折扣可把权重压到 0——此时若它是唯一候选，
+                // 下面的 Priority 退化路径会把它选出来，不会出现"敌人永远不出手"。
+                if (antiRepeat && w > 0f && ReferenceEquals(c, _lastPicked))
+                    w *= _antiRepeatFactor;
+                _weightBuf.Add(w);
             }
 
             int idx = BaseGames.Core.WeightedPick.Index(_weightBuf);
             if (idx >= 0) return _candidates[idx];
 
-            // 无正权重（合格候选权重全 0）→ 退化为按 Priority 选(并列取首个)
+            // 无正权重（合格候选权重全 0，或全被防重复折扣压平）→ 退化为按 Priority 选(并列取首个)
             return SelectByPriority(hasLOS, grounded);
         }
     }