perf: 优化流式响应内存占用和正则预编译

- 添加 record_parsed_chunks 标志，仅在 FULL 日志级别时累积 parsed_chunks
- 预编译 CJK 和敏感信息正则表达式，避免重复编译
- 优化 header 脱敏循环，预计算 lowercase 集合
- 移除 consumer_streams.py 中未使用的 message_fields 变量
- 将 SystemConfigService import 移至文件顶部

src/services/system/config.py

@@ -500,10 +500,11 @@ class SystemConfigService:
             return headers
 
         sensitive_headers = cls.get_sensitive_headers(db)
+        sensitive_lower = {h.lower() for h in sensitive_headers if isinstance(h, str) and h}
         masked_headers = {}
 
         for key, value in headers.items():
-            if key.lower() in [h.lower() for h in sensitive_headers]:
+            if key.lower() in sensitive_lower:
                 # 保留前后各4个字符，中间用星号替换
                 if len(str(value)) > 8:
                     masked_value = str(value)[:4] + "****" + str(value)[-4:]

src/services/task/service.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import re
 from collections.abc import Callable
 from typing import Any
 
@@ -18,6 +19,11 @@ from src.services.task.exceptions import TaskNotFoundError
 from src.services.task.protocol import AttemptKind, AttemptResult
 from src.services.task.schema import ExecutionResult, TaskStatusResult
 
+_SENSITIVE_PATTERN = re.compile(
+    r"(api[_-]?key|token|bearer|authorization)[=:\s]+\S+",
+    re.IGNORECASE,
+)
+
 
 class TaskService:
     """
@@ -883,7 +889,6 @@ class TaskService:
         - stop on "client error" (raise UpstreamClientRequestError)
         - if all failed, raise AllCandidatesFailedError
         """
-        import re
         from datetime import datetime, timezone
 
         import httpx
@@ -901,11 +906,6 @@ class TaskService:
         from src.services.orchestration.error_classifier import ErrorClassifier
         from src.services.system.config import SystemConfigService
 
-        _SENSITIVE_PATTERN = re.compile(
-            r"(api[_-]?key|token|bearer|authorization)[=:\s]+\S+",
-            re.IGNORECASE,
-        )
-
         def _sanitize(message: str, max_length: int = 200) -> str:
             if not message:
                 return "request_failed"

src/services/usage/consumer_streams.py

@@ -283,12 +283,10 @@ class UsageQueueConsumer:
             # 准备批量记录数据
             records: list[dict[str, Any]] = []
             message_ids: list[str] = []
-            message_fields: list[dict[str, Any]] = []
 
             for message_id, fields, event in messages:
                 records.append(_event_to_record(event))
                 message_ids.append(message_id)
-                message_fields.append(fields)
 
             # 批量写入
             await UsageService.record_usage_batch(db, records)