Add one-expiry-per-day open rhythm gate (default on).

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/strategy/clock.py

@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 from datetime import datetime
+from typing import Any
 from zoneinfo import ZoneInfo
 
 _SH = ZoneInfo("Asia/Shanghai")
@@ -38,3 +39,34 @@ def can_open_new(
 
 def group_date_ymd(now: datetime | None = None) -> str:
     return window_key(now)
+
+
+def used_expiry_ymds_for_day(db: Any, now: datetime | None = None) -> set[str]:
+    """
+    上海日历日已开过的期权到期日（groups.expiry_ymd，YYMMDD）。
+    按当日组号 G-{YYYYMMDD}-% 统计；含已平仓，用于「同到期一天只开一次」。
+    """
+    wkey = window_key(now)
+    rows = db.fetchall(
+        "SELECT DISTINCT expiry_ymd FROM groups WHERE group_id LIKE ?",
+        (f"G-{wkey}-%",),
+    )
+    out: set[str] = set()
+    for r in rows or []:
+        y = str(r["expiry_ymd"] or "").strip()
+        if y:
+            out.add(y)
+    return out
+
+
+def expiry_blocked_by_one_per_day(
+    expiry_ymd: str | None,
+    used: set[str],
+    *,
+    enabled: bool = True,
+) -> bool:
+    """开启时：候选到期已在当日用过则拦截。"""
+    if not enabled:
+        return False
+    y = str(expiry_ymd or "").strip()
+    return bool(y and y in used)