fix(equity-factor): guard non-positive recent price in momentum_12_1 (delisted-name safety)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/fxhnt/domain/strategies/equity_factor.py

@@ -29,7 +29,7 @@ def momentum_12_1_from_closes(closes: list[float]) -> float | None:
         return None
     p_then = closes[-_LOOKBACK]
     p_recent = closes[-_SKIP]
-    if p_then is None or p_then <= 0:
+    if p_then is None or p_then <= 0 or p_recent is None or p_recent <= 0:
         return None
     return p_recent / p_then - 1.0
 

tests/unit/test_equity_factor_helpers.py

@@ -19,6 +19,18 @@ def test_momentum_12_1_none_when_insufficient_history():
     assert momentum_12_1_from_closes(_ramp(50)) is None
 
 
+def test_momentum_12_1_none_when_recent_price_nonpositive():
+    closes = _ramp(300)
+    closes[-21] = 0.0  # the "recent" (skip) price is non-positive
+    assert momentum_12_1_from_closes(closes) is None
+
+
+def test_momentum_12_1_none_when_lookback_price_nonpositive():
+    closes = _ramp(300)
+    closes[-252] = 0.0  # the lookback base price is non-positive
+    assert momentum_12_1_from_closes(closes) is None
+
+
 def test_realized_vol_zero_for_constant_series():
     v = realized_vol_from_closes([100.0] * 120)
     assert v is not None and v == 0.0