diff --git a/apps/devices/views.py b/apps/devices/views.py
index 0056b8f..ffd65b9 100644
--- a/apps/devices/views.py
+++ b/apps/devices/views.py
@@ -59,6 +59,24 @@ class DeviceViewSet(viewsets.ViewSet):
                 status_code=status.HTTP_404_NOT_FOUND
             )
     
+    @action(detail=False, methods=['get'])
+    def latest(self, request):
+        """
+        获取用户最近使用的设备
+        GET /api/v1/devices/latest
+        """
+        devices = list(
+            UserDevice.objects.filter(
+                user=request.user,
+                is_active=True
+            ).select_related('device', 'device__device_type', 'spirit')
+            .order_by('-bind_time')[:1]
+        )
+        if not devices:
+            return error(code=ErrorCode.DEVICE_NOT_FOUND, message='暂无绑定设备')
+        latest = devices[0]
+        return success(data=UserDeviceSerializer(latest).data)
+
     @action(detail=False, methods=['post'])
     def verify(self, request):
         """
diff --git a/apps/spirits/serializers.py b/apps/spirits/serializers.py
index a308e25..a796cd7 100644
--- a/apps/spirits/serializers.py
+++ b/apps/spirits/serializers.py
@@ -16,11 +16,16 @@ class SpiritSerializer(serializers.ModelSerializer):
 
 class CreateSpiritSerializer(serializers.ModelSerializer):
     """创建智能体序列化器"""
-    
+
     class Meta:
         model = Spirit
         fields = ['name', 'avatar', 'prompt', 'memory', 'voice_id']
 
+    def validate_prompt(self, value):
+        if value and len(value) > 5000:
+            raise serializers.ValidationError('提示词不能超过5000个字符')
+        return value
+
 
 class SpiritListSerializer(serializers.ModelSerializer):
     """智能体列表序列化器（不含memory等大字段）"""