chore/ 精简展示AI活动的日志

api/app/agents/chat/helpers.py

@@ -1,5 +1,6 @@
 """聊天 Agent 共享工具：历史获取、格式化、存储"""
 
+import hashlib
 from dataclasses import dataclass
 from datetime import datetime
 from typing import Any, List
@@ -68,12 +69,28 @@ async def get_history_messages(conversation_id: str) -> List[Any]:
     return _lc_messages_from_rows(_human_ai_rows(history))
 
 
-def format_history_string(messages: List[Any]) -> str:
+def _sha12_utf8(text: str) -> str:
+    return hashlib.sha256((text or "").encode("utf-8")).hexdigest()[:12]
+
+
+def format_history_string(
+    messages: List[Any], *, omit_system_body: bool = False
+) -> str:
     """将 LangChain 消息列表格式化为调试日志用多段文本（含 System，不静默跳过）。"""
     history_parts: list[str] = []
     for msg in messages:
         if isinstance(msg, SystemMessage):
-            history_parts.append(f"System: {msg.content}")
+            if omit_system_body:
+                c = (
+                    (msg.content or "")
+                    if isinstance(msg.content, str)
+                    else str(msg.content)
+                )
+                history_parts.append(
+                    f"System: <omitted total_len={len(c)} sha12={_sha12_utf8(c)}>"
+                )
+            else:
+                history_parts.append(f"System: {msg.content}")
         elif isinstance(msg, HumanMessage):
             history_parts.append(f"Human: {msg.content}")
         elif isinstance(msg, AIMessage):