diff --git a/Assets/Tests/EditMode/AI/BrainBuilderTests.cs b/Assets/Tests/EditMode/AI/BrainBuilderTests.cs
index aa68f2da..e3265891 100644
--- a/Assets/Tests/EditMode/AI/BrainBuilderTests.cs
+++ b/Assets/Tests/EditMode/AI/BrainBuilderTests.cs
@@ -69,5 +69,21 @@ namespace BaseGames.Tests.EditMode.AI
             b.State("A").To("Nonexistent").When(c => true);
             Assert.Throws<System.InvalidOperationException>(() => b.Build());
         }
+
+        [Test]
+        public void RequireState_Throws_WhenStateNotDeclared()
+        {
+            var b = new BrainBuilder();
+            var ex = Assert.Throws<System.InvalidOperationException>(() => b.RequireState("Ghost"));
+            StringAssert.Contains("Ghost", ex.Message);
+        }
+
+        [Test]
+        public void RequireState_Passes_WhenStateDeclared()
+        {
+            var b = new BrainBuilder();
+            b.State("Real");
+            Assert.DoesNotThrow(() => b.RequireState("Real"));
+        }
     }
 }
diff --git a/Assets/_Game/Scripts/AI/BrainBuilder.cs b/Assets/_Game/Scripts/AI/BrainBuilder.cs
index fe64a4e6..fe0a7aea 100644
--- a/Assets/_Game/Scripts/AI/BrainBuilder.cs
+++ b/Assets/_Game/Scripts/AI/BrainBuilder.cs
@@ -28,6 +28,17 @@ namespace BaseGames.AI
 
         public GlobalBuilder Global() => new GlobalBuilder(this);
 
+        /// <summary>
+        /// 要求状态已被声明（含行为回调）。模块给"别人声明的态"挂边前调用。
+        /// 未声明即抛——否则 State() 会静默新建一个空态，敌人杵着不动且无任何报错。
+        /// </summary>
+        public void RequireState(string name)
+        {
+            if (!_states.ContainsKey(name))
+                throw new InvalidOperationException(
+                    $"BrainBuilder: 状态 '{name}' 尚未声明。请先声明它的行为（AiStateFragments.* 或 State(name)），再挂转换。");
+        }
+
         internal void AddGlobal(Transition t) => _globals.Add(t);
 
         public AiGraph Build()