feat(enemy): AiStateFragments 建态原语，新增 AbilityOnce 修死亡态重触发隐患

从 PerceptionStateMachine 的 private static 辅助方法提升为公开原语，供后续
模块化重构（骨架+可插拔模块）与定制 AiScript 复用。新增 AbilityOnce：
只在进入时触发能力、不每帧重触发，修复用 Ability() 驱动死亡态时演出播完
被 Tick 无限重播的隐患（现有 PerceptionStateMachine 因 E001 死亡能力 id
为空未暴露，本次不改它，留待 T11 整体退役）。

Assets/Tests/EditMode/AI/AiStateFragmentsTests.cs

@@ -0,0 +1,68 @@
+using NUnit.Framework;
+using BaseGames.AI;
+using BaseGames.Enemies;
+
+namespace BaseGames.Tests.EditMode.AI
+{
+    public class AiStateFragmentsTests
+    {
+        static AiRuntime Run(System.Action<BrainBuilder> build, FakeAiContext ctx)
+        {
+            var b = new BrainBuilder();
+            b.Entry("S");
+            build(b);
+            return new AiRuntime(b.Build(), ctx);
+        }
+
+        [Test]
+        public void Locomotion_SetsModeOnEnter()
+        {
+            var ctx = new FakeAiContext();
+            Run(b => AiStateFragments.Locomotion(b, "S", LocomotionMode.Patrol), ctx);
+            Assert.AreEqual(LocomotionMode.Patrol, ctx.L.CurrentMode);
+        }
+
+        [Test]
+        public void Locomotion_FaceMode_FacesLastKnown()
+        {
+            var ctx = new FakeAiContext();
+            ctx.S.Last = new UnityEngine.Vector2(3f, 0f);
+            Run(b => AiStateFragments.Locomotion(b, "S", LocomotionMode.Face), ctx);
+            Assert.AreEqual(new UnityEngine.Vector2(3f, 0f), ctx.L.FacedAt);
+        }
+
+        [Test]
+        public void Ability_RetriggersOnTick_WhenNotRunning()
+        {
+            var ctx = new FakeAiContext();
+            var rt = Run(b => AiStateFragments.Ability(b, "S", "atk"), ctx);
+            Assert.AreEqual(1, ctx.C.Used.Count);
+            ctx.C.Running = null;               // 模拟被受击打断
+            rt.Tick(0.1f);
+            Assert.AreEqual(2, ctx.C.Used.Count); // 重新触发
+        }
+
+        [Test]
+        public void AbilityOnce_DoesNotRetrigger()
+        {
+            var ctx = new FakeAiContext();
+            var rt = Run(b => AiStateFragments.AbilityOnce(b, "S", "death"), ctx);
+            Assert.AreEqual(1, ctx.C.Used.Count);
+            ctx.C.Running = null;               // 演出播完
+            rt.Tick(0.1f);
+            rt.Tick(0.1f);
+            Assert.AreEqual(1, ctx.C.Used.Count); // 不重播
+        }
+
+        [Test]
+        public void LostAllZones_TrueOnlyWhenBothZonesEmpty()
+        {
+            var ctx = new FakeAiContext();
+            Assert.IsTrue(AiStateFragments.LostAllZones(ctx));
+            ctx.S.Chase = true;
+            Assert.IsFalse(AiStateFragments.LostAllZones(ctx));
+            ctx.S.Chase = false; ctx.S.Vision = true;
+            Assert.IsFalse(AiStateFragments.LostAllZones(ctx));
+        }
+    }
+}

Assets/Tests/EditMode/AI/AiStateFragmentsTests.cs.meta

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Assets/Tests/EditMode/AI/Fakes/FakeLocomotion.cs

@@ -11,9 +11,11 @@ namespace BaseGames.Tests.EditMode.AI
         public bool IsMoving { get; set; }
         public void SetMode(LocomotionMode mode) { CurrentMode = mode; Calls.Add("SetMode:" + mode); }
         public void Approach(Transform t) { CurrentMode = LocomotionMode.Approach; Calls.Add("Approach"); }
-        public void Pursue(Vector2 p) { CurrentMode = LocomotionMode.Approach; Calls.Add("Pursue"); }
+        public Vector2 PursuedTo;
+        public void Pursue(Vector2 p) { PursuedTo = p; CurrentMode = LocomotionMode.Approach; Calls.Add("Pursue"); }
         public void MoveTo(Vector2 p) { Calls.Add("MoveTo"); }
-        public void Face(Vector2 p) { CurrentMode = LocomotionMode.Face; Calls.Add("Face"); }
+        public Vector2 FacedAt;
+        public void Face(Vector2 p) { FacedAt = p; CurrentMode = LocomotionMode.Face; Calls.Add("Face"); }
         public void Stop() { CurrentMode = LocomotionMode.Idle; Calls.Add("Stop"); }
     }
 }

Assets/_Game/Scripts/Enemies/AIBrain/Modules.meta

@@ -0,0 +1,8 @@
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Assets/_Game/Scripts/Enemies/AIBrain/Modules/AiStateFragments.cs

@@ -0,0 +1,59 @@
+using System;
+using BaseGames.AI;
+
+namespace BaseGames.Enemies
+{
+    /// <summary>
+    /// 建态原语。骨架、各模块、以及定制 AiScript 写自定义态时共用这几个形状，
+    /// 保证"进入声明意图 / 离开收尾"的契约在全项目一致。
+    /// </summary>
+    public static class AiStateFragments
+    {
+        /// <summary>共享条件：脱离全部感知（追逐区与视野区都不在）。</summary>
+        public static readonly Func<IAiContext, bool> LostAllZones =
+            x => !x.Sensor.InChaseZone() && !x.Sensor.InVisionZone();
+
+        /// <summary>由 EnemyLocomotion 驱动的态：进入 / 每帧声明移动意图，离开时停。</summary>
+        public static BrainBuilder.StateBuilder Locomotion(BrainBuilder b, string state, LocomotionMode mode)
+            => b.State(state)
+                .OnEnter(x => ApplyLocomotion(x, mode))
+                .Tick  (x => ApplyLocomotion(x, mode))
+                .OnExit(x => x.Locomotion.Stop());
+
+        /// <summary>
+        /// 由能力驱动的持续态：进入 / 每帧确保能力在跑（受击打断后自动重触发），离开中断。
+        /// 用于追击、冲锋这类"只要还在这个状态就该一直在做"的能力。
+        /// </summary>
+        public static BrainBuilder.StateBuilder Ability(BrainBuilder b, string state, string abilityId)
+            => b.State(state)
+                .OnEnter(x => EnsureAbility(x, abilityId))
+                .Tick  (x => EnsureAbility(x, abilityId))
+                .OnExit(x => x.Combat.InterruptAbilities());
+
+        /// <summary>
+        /// 由能力驱动的一次性态：只在进入时触发，不每帧重触发。
+        /// 用于死亡等一次性演出——若用 Ability()，演出播完会被 Tick 无限重播。
+        /// </summary>
+        public static BrainBuilder.StateBuilder AbilityOnce(BrainBuilder b, string state, string abilityId)
+            => b.State(state).OnEnter(x => EnsureAbility(x, abilityId));
+
+        /// <summary>
+        /// 无行为的终态。不需要在这里停移动——转入本态时，上一个态的 OnExit 已经收尾。
+        /// 用于"死亡演出交给物理状态机（EnemyBase.PerformDeath）"的敌人。
+        /// </summary>
+        public static BrainBuilder.StateBuilder Terminal(BrainBuilder b, string state)
+            => b.State(state);
+
+        static void ApplyLocomotion(IAiContext x, LocomotionMode mode)
+        {
+            if (mode == LocomotionMode.Face) x.Locomotion.Face(x.Sensor.LastKnown);
+            else                             x.Locomotion.SetMode(mode);
+        }
+
+        static void EnsureAbility(IAiContext x, string abilityId)
+        {
+            if (!string.IsNullOrEmpty(abilityId) && !x.Combat.IsAbilityRunning(abilityId))
+                x.Combat.UseAbility(abilityId);
+        }
+    }
+}

Assets/_Game/Scripts/Enemies/AIBrain/Modules/AiStateFragments.cs.meta

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