fix(HEL-485): 盘中选择当天不再整页退回昨天

交易时段缺少盘后正式数据时继续展示当天盘中行情，只有开盘前、周末和历史日期才沿用最近收盘结果。

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

tests/test_realtime_dashboard.py

@@ -1,8 +1,10 @@
 from __future__ import annotations
 
 import unittest
+from datetime import datetime, timedelta, timezone
 
 from backend.data.providers.tushare_client import TushareClient
+from backend.data.providers.tushare_helpers import calendar_is_open
 
 
 class FakeRealtimeClient(TushareClient):
@@ -130,6 +132,58 @@ class RealtimeDashboardTests(unittest.TestCase):
         self.assertEqual(dashboard["meta"]["limit_data_source"], "derived")
         self.assertIn("日线数据推算", dashboard["meta"]["notice"])
 
+    def test_calendar_open_flag_accepts_string_and_bool(self):
+        self.assertTrue(calendar_is_open(1))
+        self.assertTrue(calendar_is_open("1"))
+        self.assertTrue(calendar_is_open(True))
+        self.assertFalse(calendar_is_open(0))
+        self.assertFalse(calendar_is_open("0"))
+        self.assertFalse(calendar_is_open(False))
+
+        original_query = self.client.query
+
+        def query(api_name, params=None, fields=""):
+            if api_name == "trade_cal":
+                return [
+                    {
+                        "cal_date": params.get("start_date"),
+                        "is_open": "1",
+                        "pretrade_date": "20260907",
+                    }
+                ]
+            return original_query(api_name, params, fields)
+
+        self.client.query = query
+        trade_date, previous = self.client.resolve_trade_context("20260908")
+        self.assertEqual(trade_date, "20260908")
+        self.assertEqual(previous, "20260907")
+
+    def test_session_clock_uses_realtime_until_official_window(self):
+        today = "20260908"
+        self.client.clock = lambda: datetime(
+            2026, 9, 8, 10, 5, tzinfo=timezone(timedelta(hours=8))
+        )
+        self.assertTrue(self.client.should_use_realtime(today, today))
+        self.client.clock = lambda: datetime(
+            2026, 9, 8, 16, 10, tzinfo=timezone(timedelta(hours=8))
+        )
+        self.assertFalse(self.client.should_use_realtime(today, today))
+
+    def test_realtime_dashboard_survives_missing_limit_table(self):
+        original_query = self.client.query
+
+        def query(api_name, params=None, fields=""):
+            if api_name == "stk_limit":
+                return []
+            return original_query(api_name, params, fields)
+
+        self.client.query = query
+        TushareClient._realtime_reference_cache.clear()
+        dashboard = self.client._realtime_dashboard("20260720", "20260720", "20260717")
+        self.assertTrue(dashboard["meta"]["realtime"])
+        self.assertEqual(dashboard["meta"]["quote_count"], 3)
+        self.assertEqual(dashboard["overview"]["limit_up_count"], 0)
+
 
 if __name__ == "__main__":
     unittest.main()