diff --git a/sanguo_portfolio/runner_live.py b/sanguo_portfolio/runner_live.py
index fda5711..07e499d 100644
--- a/sanguo_portfolio/runner_live.py
+++ b/sanguo_portfolio/runner_live.py
@@ -60,6 +60,20 @@ def live_env() -> Dict[str, str]:
     }
 
 
+def _effective_trade_time(trade: Any) -> Any:
+    """成交时间守卫(2026-08-20 事故):QMT 原始成交时间经引擎 pd.to_datetime 的
+    失败形态会落成 1970-01-01 00:00:01 的 datetime——当日 9 笔 traded_at=1970
+    落库,前端"今日成交"按日期过滤全空 + 账本 trade_date 失真(T+1 视图错)。
+    年份<2000 一律视为无效,回退当前时刻:归因轮询间隔 ≤60s,日期误差只剩
+    跨日 60s 窗口,可忽略。"""
+    from datetime import datetime
+
+    v = getattr(trade, "time", None)
+    if isinstance(v, datetime) and v.year >= 2000:
+        return v
+    return datetime.now()
+
+
 def _sync_instance_trades(
     engine: Any, ledger: Any, db: str, account_id: int, strategy_name: str,
 ) -> None:
@@ -88,8 +102,8 @@ def _sync_instance_trades(
         if oid not in own_buy:
             continue  # 别家实例/手动单,不归因给本实例
         is_buy = own_buy[oid]
-        t_time = getattr(t, "time", None)
-        date_str = t_time.strftime("%Y-%m-%d") if hasattr(t_time, "strftime") else str(t_time or "")
+        t_time = _effective_trade_time(t)
+        date_str = t_time.strftime("%Y-%m-%d")
         applied = ledger.apply_trade(
             is_buy=is_buy,
             symbol=str(getattr(t, "security", "")),
diff --git a/tests/portfolio/test_live_instance_ledger.py b/tests/portfolio/test_live_instance_ledger.py
index 95a4e99..b2c13b9 100644
--- a/tests/portfolio/test_live_instance_ledger.py
+++ b/tests/portfolio/test_live_instance_ledger.py
@@ -129,6 +129,44 @@ def _fake_engine():
 
 
 class TestAttributionAndSnapshot:
+    def test_sync_time_guard_rejects_epoch_1970(self, tmp_path):
+        """2026-08-20 事故回归:引擎成交 time 落 1970 → traded_at/账本 trade_date
+        必须回退当前时刻(否则前端今日成交全空、T+1 视图把当日仓当历史仓)。"""
+        from datetime import date as _date
+
+        from sanguo_live.persistence import init_db, list_trades
+
+        db = str(tmp_path / "live.db")
+        init_db(db)
+        led = LiveInstanceLedger(initial_cash=1_000_000)
+        own = SimpleNamespace(order_id="o1", is_buy=True)
+        t_bad = SimpleNamespace(
+            order_id="o1", security="000001.XSHE", amount=100, price=10.0,
+            time=datetime(1970, 1, 1, 0, 0, 1), commission=0.0, tax=0.0)
+        engine = SimpleNamespace(
+            get_orders=lambda: {"o1": own},
+            get_trades=lambda: {"t1": t_bad},
+            context=SimpleNamespace(portfolio=SimpleNamespace(positions={})),
+        )
+        _sync_instance_trades(engine, led, db, 44, "channel_test")
+        rows = list_trades(db, 44)
+        assert len(rows) == 1
+        assert rows[0]["traded_at"].startswith(_date.today().isoformat())
+        # 账本按今天记账 → 当日买入冻结(T+1),不再被当历史仓
+        view = led.positions_view(_date.today().isoformat())
+        assert view["000001.XSHE"]["closeable_amount"] == 0
+
+    def test_sync_time_guard_keeps_valid_time(self, tmp_path):
+        from sanguo_live.persistence import init_db, list_trades
+
+        db = str(tmp_path / "live.db")
+        init_db(db)
+        led = LiveInstanceLedger(initial_cash=1_000_000)
+        engine = _fake_engine()
+        _sync_instance_trades(engine, led, db, 44, "channel_test")
+        rows = list_trades(db, 44)
+        assert rows[0]["traded_at"] == "2026-08-19 09:35:00"  # 有效时间原样保留
+
     def test_sync_attributes_only_own_orders(self, tmp_path):
         from sanguo_live.persistence import init_db, list_trades