Fix post-close auto sell: restore missing spot min-size helpers used by sim sell.

Sell was silently failing on ImportError; surface sell result in close alert notes.

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

lib/options/options_spot_bridge_lib.py

@@ -177,6 +177,50 @@ def fetch_trading_coin_available(ex: Any, ccy: str) -> float | None:
         return None
 
 
+def spot_min_sell_sz(ex: Any, ccy: str) -> float:
+    """OKX 现货最小卖出量(base ccy);读不到则用保守默认."""
+    ccy_u = (ccy or "").strip().upper()
+    defaults = {"BTC": 1e-5, "ETH": 1e-4}
+    default = float(defaults.get(ccy_u, 1e-4))
+    inst_id = spot_quote_inst_id(ccy_u)
+    if not inst_id:
+        return default
+    try:
+        if ex is not None and hasattr(ex, "public_get_public_instruments"):
+            resp = ex.public_get_public_instruments({"instType": "SPOT", "instId": inst_id})
+            data = (resp or {}).get("data") or []
+            if data:
+                raw = data[0].get("minSz")
+                if raw is not None and str(raw).strip() != "":
+                    return float(raw)
+    except Exception:
+        pass
+    try:
+        if ex is not None and hasattr(ex, "market"):
+            m = ex.market(inst_id.replace("-", "/"))
+            lim = (m or {}).get("limits") or {}
+            amt = (lim.get("amount") or {}).get("min")
+            if amt is not None:
+                return float(amt)
+    except Exception:
+        pass
+    return default
+
+
+def is_sellable_spot_coin(ex: Any, ccy: str, amount: float) -> bool:
+    """数量是否达到现货最小卖出门槛."""
+    try:
+        amt = float(amount or 0)
+    except (TypeError, ValueError):
+        return False
+    if amt <= 0:
+        return False
+    try:
+        return amt + 1e-15 >= float(spot_min_sell_sz(ex, ccy))
+    except Exception:
+        return amt > 0
+
+
 def spot_market_buy_coin_with_usdt(
     ex: Any,
     *,