diff --git a/tests/test_badhaka_rules.py b/tests/test_badhaka_rules.py
new file mode 100644
index 00000000..86a9369b
--- /dev/null
+++ b/tests/test_badhaka_rules.py
@@ -0,0 +1,25 @@
+import sys
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[1]
+sys.path.insert(0, str(ROOT / 'scripts'))
+
+from yoga_engine import YogaContext  # noqa: E402
+
+
+def test_badhaka_houses_follow_chara_sthira_dual_rule_for_all_lagnas() -> None:
+    expected = {
+        'Aries': 11, 'Cancer': 11, 'Libra': 11, 'Capricorn': 11,
+        'Taurus': 9, 'Leo': 9, 'Scorpio': 9, 'Aquarius': 9,
+        'Gemini': 7, 'Virgo': 7, 'Sagittarius': 7, 'Pisces': 7,
+    }
+    for ascendant, house in expected.items():
+        context = YogaContext({}, ascendant)
+        assert context.is_badhaka(house) is True
+        assert context.is_badhaka(1 if house != 1 else 2) is False
+
+
+def test_badhaka_rule_is_structural_and_does_not_emit_lifespan_claims() -> None:
+    source = (ROOT / 'scripts' / 'yoga_engine.py').read_text(encoding='utf-8')
+    assert '过早死亡风险' not in source