fix(HEL-494): 盘中双免费源故障切换并禁止问天假0覆盖

主源东财失败后自动改走腾讯行情，成功结果写入缓存；两源都失败时返回最近真实快照并标明延迟，不再显示假0。

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: multica-agent <github@multica.ai>

tests/test_hel494_regressions.py

@@ -216,6 +216,44 @@ class MemberQuoteCoverageTests(unittest.TestCase):
         self.assertEqual(source, "datahub")
         client.try_quotes.assert_not_called()
 
+    def test_eastmoney_failure_uses_tencent_member_quotes(self) -> None:
+        client = TushareClient(token="demo")
+        wanted = ["000737.SZ", "000630.SZ"]
+        client.try_market_quotes = MagicMock(return_value=None)
+        client.try_quotes = MagicMock(return_value=None)
+        aggregator = MagicMock()
+        aggregator.eastmoney_stock_quotes.side_effect = RuntimeError("HTTP 503")
+        aggregator.tencent_stock_quotes.return_value = [
+            {"ts_code": "000737.SZ", "close": 12.3, "pre_close": 11.2},
+            {"ts_code": "000630.SZ", "close": 4.5, "pre_close": 4.4},
+        ]
+        client.realtime_aggregator = aggregator
+        client._free_realtime_quotes = MagicMock(side_effect=AssertionError("tencent already won"))
+        rows, source = client._load_member_realtime_quotes(wanted, "20260908")
+        self.assertEqual(len(rows), 2)
+        self.assertEqual(source, "tencent_qt")
+        aggregator.tencent_stock_quotes.assert_called_once()
+
+    def test_delayed_hub_quotes_are_kept_not_zeroed(self) -> None:
+        client = TushareClient(token="demo")
+        delayed = [
+            {
+                "ts_code": "000737.SZ",
+                "close": 12.3,
+                "pre_close": 11.2,
+                "delayed": True,
+                "delay_seconds": 90,
+                "delay_notice": "主备免费行情均暂不可用，显示 90 秒前的真实快照",
+            }
+        ]
+        client.try_market_quotes = MagicMock(return_value=delayed)
+        client.try_quotes = MagicMock()
+        client.realtime_aggregator = MagicMock()
+        rows, source = client._load_member_realtime_quotes(["000737.SZ"], "20260908")
+        self.assertEqual(source, "datahub_delayed")
+        self.assertEqual(rows[0]["close"], 12.3)
+        client.try_quotes.assert_not_called()
+
     def test_ignores_non_member_quotes_from_market_snapshot(self) -> None:
         client = TushareClient(token="demo")
         client.try_market_quotes = MagicMock(
@@ -231,6 +269,36 @@ class MemberQuoteCoverageTests(unittest.TestCase):
         )
         self.assertEqual([row["ts_code"] for row in rows], ["000737.SZ"])
 
+    def test_local_sw_members_survive_tushare_outage(self) -> None:
+        import tempfile
+        from pathlib import Path
+
+        from backend.data.providers import tushare_industries as module
+
+        client = TushareClient(token="demo")
+        stored = [
+            {
+                "ts_code": "000737.SZ",
+                "name": "北方铜业",
+                "l2_code": "801074.SI",
+                "in_date": "20200101",
+                "out_date": "",
+            }
+        ]
+        with tempfile.TemporaryDirectory() as tmp:
+            original = module._SW_MEMBER_DIR
+            module._SW_MEMBER_DIR = Path(tmp)
+            try:
+                client._sw_member_cache.clear()
+                client._write_local_sw_members("801074.SI", stored)
+                client.query = MagicMock(side_effect=TushareError("index_member_all down"))
+                members = client._sw_sector_members("801074.SI", "20260908")
+            finally:
+                module._SW_MEMBER_DIR = original
+                client._sw_member_cache.clear()
+        self.assertEqual([item["ts_code"] for item in members], ["000737.SZ"])
+        client.query.assert_not_called()
+
     def test_closed_keeps_daily_inner_when_sw_daily_missing(self) -> None:
         client = TushareClient(token="demo")
         client.resolve_trade_context = lambda _date: ("20260908", "20260907")