Split OO budget per leg and size Call/Put independently.

Each half of the risk budget buys its own qty from ask; equal qty no longer forced.

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

backend/tests/test_oo_selection_sizing.py

@@ -46,6 +46,25 @@ def test_select_oo_pair_same_expiry(tmp_path=None) -> None:
 
 
 def test_compute_oo_sizing_1_1_and_reward() -> None:
+    r = compute_oo_sizing(
+        budget=100.0,
+        call_ask=5.0,
+        put_ask=10.0,  # Put 更贵 → 数量更少
+        fee_rate=0.0,
+        index_px=2000.0,
+        cushion=1.0,  # 测纯平分，不预留
+        reward_ratio=2.0,
+    )
+    assert r.ok
+    # 各 50U：Call 50/5=10，Put 50/10=5
+    assert r.call_qty_eth == 10.0
+    assert r.put_qty_eth == 5.0
+    assert abs(float(r.net_profit_target or 0) - 200.0) < 1e-9
+    assert abs(float(r.call_premium or 0) - 50.0) < 1e-6
+    assert abs(float(r.put_premium or 0) - 50.0) < 1e-6
+
+
+def test_compute_oo_sizing_equal_asks() -> None:
     r = compute_oo_sizing(
         budget=100.0,
         call_ask=5.0,
@@ -56,7 +75,9 @@ def test_compute_oo_sizing_1_1_and_reward() -> None:
         reward_ratio=2.0,
     )
     assert r.ok
-    assert r.qty_eth == 9.2
+    # 各腿 46U / 5 = 9.2
+    assert r.call_qty_eth == 9.2
+    assert r.put_qty_eth == 9.2
     assert abs(float(r.net_profit_target or 0) - 200.0) < 1e-9
     assert float(r.call_premium or 0) + float(r.put_premium or 0) <= 92.0 + 1e-6