diff --git a/gateway/scripts/chat_bridge.py b/gateway/scripts/chat_bridge.py
index 0935cc3..f5b7966 100644
--- a/gateway/scripts/chat_bridge.py
+++ b/gateway/scripts/chat_bridge.py
@@ -193,6 +193,27 @@ _TOOLS = [
                 }
             }
         }
+    },
+    {
+        "type": "function",
+        "function": {
+            "name": "search_sessions",
+            "description": "跨所有 session 搜索指定关键词，自动定位最相关的 session。不知道应该查哪个 session 时用这个。返回匹配到的 session 标题、匹配条数和消息摘要片段。",
+            "parameters": {
+                "type": "object",
+                "properties": {
+                    "query": {
+                        "type": "string",
+                        "description": "搜索关键词，如项目名、文件名、话题等"
+                    },
+                    "max_sessions": {
+                        "type": "integer",
+                        "description": "最多搜几个 session，默认 5"
+                    }
+                },
+                "required": ["query"]
+            }
+        }
     }
 ]
 _MAX_TOOL_LOOPS = 30  # 超限后走 clean final force，不再泄漏 XML
@@ -212,6 +233,51 @@ def _run_tool_command(cmd: str) -> str:
         return f"(执行失败: {e})"
 
 
+def _search_all_sessions(query: str, max_sessions: int = 5) -> str:
+    """Search ALL recent sessions for a query. Returns formatted results."""
+    import sqlite3, json
+    db = _SERVE_DB
+    if not os.path.exists(db):
+        return f"(session 数据库不存在: {db})"
+    try:
+        conn = sqlite3.connect(db)
+        conn.row_factory = sqlite3.Row
+        # Get recent sessions
+        sessions = conn.execute(
+            "SELECT id, title, time_updated FROM session ORDER BY time_updated DESC LIMIT ?",
+            (max_sessions * 3,),
+        ).fetchall()
+        results = []
+        for s in sessions:
+            sid = s["id"]
+            title = s["title"] or "(无标题)"
+            # Search messages in this session
+            msgs = conn.execute(
+                f"""SELECT m.id, m.data FROM message m
+                    WHERE m.session_id=? ORDER BY m.time_created DESC LIMIT 50""",
+                (sid,),
+            ).fetchall()
+            matches = []
+            for m in msgs:
+                try:
+                    d = json.loads(m["data"])
+                    content = d.get("content", "")
+                    if query.lower() in content.lower():
+                        matches.append(content[:200])
+                except (json.JSONDecodeError, ValueError):
+                    continue
+                if len(matches) >= 3:
+                    break
+            if matches:
+                results.append(f"[{title}]({sid[:16]}...): {len(matches)}条匹配\n" + "\n".join(f"  · {m}" for m in matches))
+        conn.close()
+        if not results:
+            return f"(搜索 \"{query}\" 未在任何 session 中找到匹配)"
+        return "搜索到相关 session：\n\n" + "\n\n".join(results)
+    except Exception as e:
+        return f"(搜索出错: {e})"
+
+
 # ── Serve session DB path ──
 _SERVE_DB = os.path.join(
     os.environ.get("USERPROFILE", "C:\\Users\\hmo"),
@@ -469,6 +535,17 @@ class SessionBridge:
                     ctx = extract_session_context(sid, limit=limit)
                     output = ctx if ctx else f"(session {sid}: no messages)"
                     _logger.info("  tool: session_search → %s (%d chars)", sid[:32], len(output))
+
+                elif fn_name == "search_sessions":
+                    try:
+                        fn_args = json.loads(fn_args_str)
+                        query = fn_args.get("query", "")
+                        max_sessions = min(int(fn_args.get("max_sessions", 5)), 20)
+                    except (json.JSONDecodeError, ValueError, TypeError):
+                        query = ""
+                        max_sessions = 5
+                    output = _search_all_sessions(query, max_sessions)
+                    _logger.info("  tool: search_sessions query=%s (%d chars)", query[:40], len(output))
                 else:
                     output = f"(unknown tool: {fn_name})"
 
@@ -552,6 +629,12 @@ class SessionBridge:
             "否则被视为空话。只说不做比不说更糟糕。\n"
             "不确定该怎么做时，先 run_command 查一下再决定。\n"
             "\n"
+            "=== 回答问题前先搜 session ===\n"
+            "当被问到项目状态、代码位置、近期工作、其他人说过什么等事实性问题时，\n"
+            "**必须先使用 search_sessions 或 session_search 找到证据再回答**。\n"
+            "不要凭你当前 session 里的记忆回答——你的 session 可能不是最相关的。\n"
+            "正确流程：search_sessions(关键词) → 找到相关 session → session_search(具体 session) → 再回答\n"
+            "\n"
             "=== 写文件的正确方式 ===\n"
             "用 Python 一次性写完所有内容，不要分多次调用。\n"
             "错误示例（会覆盖，每调用一次就清空一次）：python -c \"open('file', 'w').write('一行')\"\n"