diff --git a/backend/app/services/kline_sync.py b/backend/app/services/kline_sync.py
index 06e3728..fbaf635 100644
--- a/backend/app/services/kline_sync.py
+++ b/backend/app/services/kline_sync.py
@@ -1277,29 +1277,38 @@ def fetch_adj_factor_single(symbol: str) -> pl.DataFrame:
     return _normalize_adj_factor(raw)
 
 
+def _as_beijing(d: datetime) -> datetime:
+    """落盘的分钟 datetime 是北京墙钟 naive, 带上北京时区再交给取数窗口。
+
+    naive 值经 _datetime_to_ms 会被 .timestamp() 按服务器本地时区解释, 与同
+    窗口另一端的服务器本地时间混用后整体错位 (UTC 容器上错 8 小时)。
+    """
+    return d if d.tzinfo is not None else d.replace(tzinfo=CN_TZ)
+
+
 def _latest_minute_datetime(repo: KlineRepository) -> datetime | None:
-    """本地分钟 K 数据的最新时间。"""
+    """本地分钟 K 数据的最新时间 (北京时区)。"""
     try:
         res = repo.execute_one("SELECT max(datetime) FROM kline_minute")
         if res and res[0]:
             d = res[0]
             if isinstance(d, datetime):
-                return d
-            return datetime.fromisoformat(str(d))
+                return _as_beijing(d)
+            return _as_beijing(datetime.fromisoformat(str(d)))
     except Exception:  # noqa: BLE001
         pass
     return None
 
 
 def _earliest_minute_datetime(repo: KlineRepository) -> datetime | None:
-    """本地分钟 K 数据的最早时间 (用于向前扩展的起点)。"""
+    """本地分钟 K 数据的最早时间 (北京时区, 用于向前扩展的起点)。"""
     try:
         res = repo.execute_one("SELECT min(datetime) FROM kline_minute")
         if res and res[0]:
             d = res[0]
             if isinstance(d, datetime):
-                return d
-            return datetime.fromisoformat(str(d))
+                return _as_beijing(d)
+            return _as_beijing(datetime.fromisoformat(str(d)))
     except Exception:  # noqa: BLE001
         pass
     return None
@@ -1421,7 +1430,9 @@ def sync_and_persist_minute(
     # 迁移:旧版按 symbol= 分区转为 date= 分区
     _migrate_symbol_to_date_partition(repo)
 
-    now = datetime.now()
+    # 窗口两端统一为北京时区: 起止点会与本地分钟 K 的北京墙钟混用, 用服务器
+    # 本地时间会让窗口整体错位 (UTC 容器上起点晚于终点, 增量补拉一个请求都发不出)。
+    now = cn_now()
 
     if extend_backward:
         # 向前扩展模式: 从本地最早数据往前补, 叠加已有数据避免缺口。
diff --git a/backend/tests/test_kline_sync_timezone.py b/backend/tests/test_kline_sync_timezone.py
index a25f78d..dfee85c 100644
--- a/backend/tests/test_kline_sync_timezone.py
+++ b/backend/tests/test_kline_sync_timezone.py
@@ -5,7 +5,11 @@ fetch_minute_single 构造的 naive datetime 会被 _datetime_to_ms 的 .timesta
 """
 from __future__ import annotations
 
-from datetime import date, datetime
+from datetime import date, datetime, timedelta
+from types import SimpleNamespace
+from unittest.mock import MagicMock
+
+import polars as pl
 
 from app.market_time import CN_TZ
 from app.services import kline_sync
@@ -41,3 +45,70 @@ def test_fetch_minute_single_window_is_beijing_wall_clock(monkeypatch):
     end = datetime.fromtimestamp(captured["end_ms"] / 1000, tz=CN_TZ)
     assert (start.date(), start.hour, start.minute) == (date(2026, 8, 14), 9, 25)
     assert (end.date(), end.hour, end.minute) == (date(2026, 8, 14), 15, 5)
+
+
+def _capture_minute_window(monkeypatch, tmp_path, local_dt: datetime, **kwargs) -> dict:
+    """桩掉 sync_and_persist_minute 的外部依赖, 只截获传给取数层的时间窗口。
+
+    local_dt 模拟 kline_minute 里的极值 (落盘口径为北京墙钟 naive)。
+    """
+    captured: dict = {}
+
+    def _fake_sync_minute_batch(symbols, **call_kwargs):
+        captured.update(call_kwargs)
+        return pl.DataFrame()
+
+    monkeypatch.setattr(kline_sync.preferences, "get_minute_data_provider", lambda: "tickflow")
+    monkeypatch.setattr(kline_sync.preferences, "get_minute_sync_segment_days", lambda: 20)
+    monkeypatch.setattr(kline_sync, "_cleanup_null_datetime_minute", lambda repo: None)
+    monkeypatch.setattr(kline_sync, "_migrate_symbol_to_date_partition", lambda repo: None)
+    monkeypatch.setattr(kline_sync, "resolve_limit", lambda *a, **kw: SimpleNamespace(batch=100, rpm=30))
+    monkeypatch.setattr(kline_sync, "sync_minute_batch", _fake_sync_minute_batch)
+
+    repo = MagicMock()
+    repo.store.data_dir = tmp_path
+    repo.execute_one = lambda sql: (local_dt,)
+    kline_sync.sync_and_persist_minute(
+        ["600000.SH"],
+        repo,
+        CapabilitySet({Cap.KLINE_MINUTE_BATCH: CapabilityLimits()}),
+        **kwargs,
+    )
+    return captured
+
+
+def test_sync_and_persist_minute_incremental_window_is_beijing_wall_clock(monkeypatch, tmp_path):
+    """增量分钟同步: 起点取自本地分钟 K 的北京墙钟, 终点必须同口径。
+
+    终点用服务器本地墙钟时, _datetime_to_ms 会把两端按同一本地时区换算 →
+    UTC 容器上起点(北京 14:30)反而晚于终点, 一个请求都发不出去, 分钟 K 永远
+    停在首次拉取的位置。
+    """
+    local_latest = datetime(2026, 8, 14, 14, 30)  # 本地最新分钟 K: 北京墙钟 naive
+
+    captured = _capture_minute_window(monkeypatch, tmp_path, local_latest)
+    start, end = captured["start_time"], captured["end_time"]
+
+    assert start.utcoffset() == timedelta(hours=8)
+    assert end.utcoffset() == timedelta(hours=8)
+    assert start < end
+    assert datetime.fromtimestamp(
+        kline_sync._datetime_to_ms(start) / 1000, tz=CN_TZ
+    ) == local_latest.replace(tzinfo=CN_TZ)
+
+
+def test_sync_and_persist_minute_extend_backward_window_is_beijing_wall_clock(monkeypatch, tmp_path):
+    """向前扩展: 终点取自本地最早分钟 K 的北京墙钟, 同样不能被服务器时区重解释。"""
+    local_earliest = datetime(2026, 8, 14, 9, 30)
+
+    captured = _capture_minute_window(
+        monkeypatch, tmp_path, local_earliest, days=5, extend_backward=True,
+    )
+    start, end = captured["start_time"], captured["end_time"]
+
+    assert start.utcoffset() == timedelta(hours=8)
+    assert end.utcoffset() == timedelta(hours=8)
+    assert end - start == timedelta(days=7)  # 5 交易日 x 7/5
+    assert datetime.fromtimestamp(
+        kline_sync._datetime_to_ms(end) / 1000, tz=CN_TZ
+    ) == local_earliest.replace(tzinfo=CN_TZ)