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

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

backend/app/strategy/engine.py

@@ -82,6 +82,9 @@ class StrategyEngine:
         )
         rest_sec = self.ledger.get_setting_int("rest_seconds", s.rest_seconds)
         skip_weekends = self.ledger.get_setting_bool("skip_weekends", s.skip_weekends)
+        one_expiry_per_day = self.ledger.get_setting_bool(
+            "one_expiry_per_day", s.one_expiry_per_day
+        )
         leverage = self.ledger.get_setting_float("leverage", s.leverage)
         perp_mm = str(
             self.ledger.get_setting_str("perp_margin_mode", s.perp_margin_mode)
@@ -213,6 +216,7 @@ class StrategyEngine:
             "rest_left_sec": rest_left,
             "rest_seconds": rest_sec,
             "skip_weekends": skip_weekends,
+            "one_expiry_per_day": one_expiry_per_day,
             "exit_mode": exit_mode,
             "net_profit_target": net_target,
             "premium_exit_multiple": prem_mult,
@@ -824,6 +828,27 @@ class StrategyEngine:
 
         self._set_state(phase="wait_signal")
         pick = await get_session().pick_for_open_async()
+        one_expiry_per_day = self.ledger.get_setting_bool(
+            "one_expiry_per_day", s.one_expiry_per_day
+        )
+        if pick is not None and one_expiry_per_day:
+            from .clock import (
+                expiry_blocked_by_one_per_day,
+                used_expiry_ymds_for_day,
+            )
+
+            used = used_expiry_ymds_for_day(self.db)
+            if expiry_blocked_by_one_per_day(
+                pick.pair.expiry_ymd, used, enabled=True
+            ):
+                self._set_state(
+                    phase="idle",
+                    last_error=(
+                        f"同到期日一天只开一次：今日已用过 {pick.pair.expiry_ymd}，"
+                        "请等下一到期日"
+                    ),
+                )
+                return
         if pick is None:
             try:
                 from .open_capacity import assess_open_capacity, funds_gate_blocks