Revise strategy: TTM+ATM+leverage option pick, % exit, perp leverage/margin.

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

backend/tests/test_instruments.py

@@ -4,7 +4,10 @@ from datetime import datetime
 from zoneinfo import ZoneInfo
 
 from app.market.instruments import (
+    hours_until_expiry,
+    list_eligible_expiry_ymds,
     next_session_expiry_ymd,
+    option_leverage,
     parse_option_inst_id,
     pick_atm_strike,
     select_option_pair,
@@ -48,3 +51,26 @@ def test_select_option_pair_atm() -> None:
     assert pair.strike == 3500
     assert pair.call_inst_id.endswith("-3500-C")
     assert pair.put_inst_id.endswith("-3500-P")
+
+
+def test_eligible_skips_short_ttm() -> None:
+    # 2026-07-25 08:30 SH：当日 16:00 到期仅约 7.5h，应跳过 260725，选 260726
+    now = datetime(2026, 7, 25, 8, 30, tzinfo=_SH)
+    rows = [
+        {"instId": "ETH-USD_UM-260725-1850-C", "state": "live"},
+        {"instId": "ETH-USD_UM-260725-1850-P", "state": "live"},
+        {"instId": "ETH-USD_UM-260726-1850-C", "state": "live"},
+        {"instId": "ETH-USD_UM-260726-1850-P", "state": "live"},
+    ]
+    assert hours_until_expiry("260725", now) < 12
+    assert hours_until_expiry("260726", now) >= 12
+    eligible = list_eligible_expiry_ymds(rows, min_hours=12, now=now)
+    assert eligible == ["260726"]
+    pair = select_option_pair(rows, mark_px=1853, min_hours=12, now=now)
+    assert pair is not None
+    assert pair.expiry_ymd == "260726"
+
+
+def test_option_leverage() -> None:
+    assert abs((option_leverage(1850, 18.5) or 0) - 100) < 1e-9
+    assert option_leverage(1850, 0) is None