fix(memory): improve optimistic lock resilience in access history manager

- Increase max_retries from 3 to 5 for concurrent conflict recovery
- Add randomized exponential backoff between retries to reduce contention
- Merge duplicate node accesses in batch operations to avoid self-conflicts
- Support access_times parameter for merged batch access counting
- Add Community node label support in atomic update content field map

api/app/core/memory/storage_services/forgetting_engine/access_history_manager.py

@@ -57,7 +57,7 @@ class AccessHistoryManager:
         self,
         connector: Neo4jConnector,
         actr_calculator: ACTRCalculator,
-        max_retries: int = 3
+        max_retries: int = 5
     ):
         """
         初始化访问历史管理器
@@ -76,7 +76,8 @@ class AccessHistoryManager:
         node_id: str,
         node_label: str,
         end_user_id: Optional[str] = None,
-        current_time: Optional[datetime] = None
+        current_time: Optional[datetime] = None,
+        access_times: int = 1
     ) -> Dict[str, Any]:
         """
         记录节点访问并原子性更新所有相关字段
@@ -93,6 +94,7 @@ class AccessHistoryManager:
             node_label: 节点标签（Statement, ExtractedEntity, MemorySummary）
             end_user_id: 组ID（可选，用于过滤）
             current_time: 当前时间（可选，默认使用系统时间）
+            access_times: 本次访问次数（默认1，批量合并时可能大于1）
         
         Returns:
             Dict[str, Any]: 更新后的节点数据，包含：
@@ -134,7 +136,8 @@ class AccessHistoryManager:
                 update_data = await self._calculate_update(
                     node_data=node_data,
                     current_time=current_time,
-                    current_time_iso=current_time_iso
+                    current_time_iso=current_time_iso,
+                    access_times=access_times
                 )
                 
                 # 步骤3：原子性更新节点（使用事务）
@@ -149,15 +152,21 @@ class AccessHistoryManager:
                     f"成功记录访问: {node_label}[{node_id}], "
                     f"activation={update_data['activation_value']:.4f}, "
                     f"access_count={update_data['access_count']}"
+                    f"{f', 合并访问次数={access_times}' if access_times > 1 else ''}"
                 )
                 
                 return updated_node
                 
             except Exception as e:
                 if attempt < self.max_retries - 1:
+                    # 随机退避：避免并发请求同时重试再次冲突
+                    import random
+                    backoff = random.uniform(0.05, 0.2) * (attempt + 1)
                     logger.warning(
-                        f"访问记录失败（尝试 {attempt + 1}/{self.max_retries}）: {str(e)}"
+                        f"访问记录失败（尝试 {attempt + 1}/{self.max_retries}），"
+                        f"{backoff:.3f}s 后重试: {str(e)}"
                     )
+                    await asyncio.sleep(backoff)
                     continue
                 else:
                     logger.error(
@@ -179,10 +188,11 @@ class AccessHistoryManager:
         批量记录多个节点的访问
         
         为提高性能，批量更新多个节点的访问历史。
-        每个节点独立更新，失败的节点不影响其他节点。
+        对同一个节点的多次访问会先在内存中合并，只发起一次更新，
+        从而避免同节点并发写入导致的乐观锁冲突。
         
         Args:
-            node_ids: 节点ID列表
+            node_ids: 节点ID列表（可包含重复ID）
             node_label: 节点标签（所有节点必须是同一类型）
             end_user_id: 组ID（可选）
             current_time: 当前时间（可选）
@@ -196,25 +206,40 @@ class AccessHistoryManager:
         if current_time is None:
             current_time = datetime.now()
         
-        # PERFORMANCE FIX: Process all nodes in parallel instead of sequentially
+        # 合并同一节点的访问次数，避免对同一节点并发写入
-        tasks = []
+        access_count_map: Dict[str, int] = {}
         for node_id in node_ids:
+            access_count_map[node_id] = access_count_map.get(node_id, 0) + 1
+        
+        merged_count = len(node_ids) - len(access_count_map)
+        if merged_count > 0:
+            logger.info(
+                f"批量访问合并: 原始={len(node_ids)}, "
+                f"去重后={len(access_count_map)}, 合并={merged_count}"
+            )
+        
+        # 对去重后的节点并行发起更新
+        tasks = []
+        for node_id, access_times in access_count_map.items():
             task = self.record_access(
                 node_id=node_id,
                 node_label=node_label,
                 end_user_id=end_user_id,
-                current_time=current_time
+                current_time=current_time,
+                access_times=access_times
             )
-            tasks.append(task)
+            tasks.append((node_id, task))
         
         # Execute all tasks in parallel
-        task_results = await asyncio.gather(*tasks, return_exceptions=True)
+        task_results = await asyncio.gather(
+            *[t for _, t in tasks], return_exceptions=True
+        )
         
         # Collect successful results and count failures
         results = []
         failed_count = 0
         
-        for node_id, result in zip(node_ids, task_results):
+        for (node_id, _), result in zip(tasks, task_results):
             if isinstance(result, Exception):
                 failed_count += 1
                 logger.warning(
@@ -225,7 +250,7 @@ class AccessHistoryManager:
         
         batch_duration = time.time() - batch_start
         logger.info(
-            f"[PERF] 批量访问记录完成: 成功 {len(results)}/{len(node_ids)}, "
+            f"[PERF] 批量访问记录完成: 成功 {len(results)}/{len(access_count_map)}, "
             f"失败 {failed_count}, 耗时 {batch_duration:.4f}s"
         )
         
@@ -532,7 +557,8 @@ class AccessHistoryManager:
         self,
         node_data: Dict[str, Any],
         current_time: datetime,
-        current_time_iso: str
+        current_time_iso: str,
+        access_times: int = 1
     ) -> Dict[str, Any]:
         """
         计算更新数据
@@ -541,6 +567,7 @@ class AccessHistoryManager:
             node_data: 当前节点数据
             current_time: 当前时间（datetime对象）
             current_time_iso: 当前时间（ISO格式字符串）
+            access_times: 本次访问次数（合并后可能大于1）
         
         Returns:
             Dict[str, Any]: 更新数据，包含所有需要更新的字段
@@ -551,8 +578,8 @@ class AccessHistoryManager:
         if importance_score is None:
             importance_score = 0.5
         
-        # 追加新的访问时间
+        # 追加新的访问时间（合并场景下追加多条相同时间戳）
-        new_access_history = access_history + [current_time_iso]
+        new_access_history = access_history + [current_time_iso] * access_times
         
         # 修剪访问历史（如果过长）
         access_history_dt = [
@@ -642,7 +669,8 @@ class AccessHistoryManager:
             content_field_map = {
                 'Statement': 'n.statement as statement',
                 'MemorySummary': 'n.content as content',
-                'ExtractedEntity': 'null as content_placeholder'  # 占位符，后续会被过滤
+                'ExtractedEntity': 'null as content_placeholder',  # 占位符，后续会被过滤
+                'Community': 'n.summary as summary'
             }
             
             # 显式检查节点类型，不支持的类型抛出错误