Fix semi open stalls: one-leg asks, OTM realign, clearer pick errors.

Monitor no longer shows ATM Put bias while semi-auto is authorized for Call.

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

backend/app/strategy/signal.py

@@ -76,15 +76,16 @@ def decide_fixed(
 ) -> Signal | None:
     """
     固定方向：
-    - 永续多 → 买 Put
-    - 永续空 → 买 Call
+    - 永续多 → 买 Put（只需 Put 卖一）
+    - 永续空 → 买 Call（只需 Call 卖一）
+    对侧卖一缺失时用本侧占位，避免半自动虚值因对侧盘口空而拒单。
     """
-    if call_ask is None or put_ask is None:
-        return None
     side = (perp_side or "").strip().lower()
-    ca = float(call_ask)
-    pa = float(put_ask)
     if side == "long":
+        if put_ask is None or float(put_ask) <= 0:
+            return None
+        pa = float(put_ask)
+        ca = float(call_ask) if call_ask is not None and float(call_ask) > 0 else pa
         return Signal(
             bias="fixed_long_put",
             option_side="put",
@@ -93,6 +94,10 @@ def decide_fixed(
             put_ask=pa,
         )
     if side == "short":
+        if call_ask is None or float(call_ask) <= 0:
+            return None
+        ca = float(call_ask)
+        pa = float(put_ask) if put_ask is not None and float(put_ask) > 0 else ca
         return Signal(
             bias="fixed_short_call",
             option_side="call",