diff --git a/services/logic/app/engine/chart.py b/services/logic/app/engine/chart.py
index b78656f..c5c4b39 100644
--- a/services/logic/app/engine/chart.py
+++ b/services/logic/app/engine/chart.py
@@ -97,7 +97,9 @@ def build_chart(engine: EphemerisEngine, moment: ChartMoment, house_system: str
     asc = H.compute_asc(ramc, eps, moment.lat)
     mc = H.compute_mc(ramc, eps)
     system = house_system if house_system in H.SYSTEMS else H.WHOLE_SIGN
-    cusp_list = H.cusps(asc, mc, system)   # tropikalne — geometria domów jest niezmiennicza
+    # cusps_for, nie cusps: to drugie zna tylko trzy systemy dzielące ekliptykę.
+    # Systemy egzotyczne dzielą inne koła wielkie i potrzebują pełnego (RAMC, ε, φ).
+    cusp_list = H.cusps_for(ramc, eps, moment.lat, system)   # tropikalne — geometria domów jest niezmiennicza
 
     def _cusps_out(cl: list[float]) -> list[dict]:
         """Cuspy → wiersze pod UI/kosmogram: znak, stopień w znaku, długość, glif."""
@@ -132,7 +134,7 @@ def build_chart(engine: EphemerisEngine, moment: ChartMoment, house_system: str
     if len(ordered) > 1:
         result["house_systems"] = []
         for s in ordered:
-            cl = cusp_list if s == system else H.cusps(asc, mc, s)
+            cl = cusp_list if s == system else H.cusps_for(ramc, eps, moment.lat, s)
             result["house_systems"].append({"system": s, "cusps": _cusps_out(cl)})
             for pdict, obj in zip(result["positions"], positions):
                 pdict.setdefault("houses", {})[s] = H.assign_house(obj.longitude, cl)
diff --git a/services/logic/tests/test_chart.py b/services/logic/tests/test_chart.py
index 5cd4180..9d30755 100644
--- a/services/logic/tests/test_chart.py
+++ b/services/logic/tests/test_chart.py
@@ -2,6 +2,9 @@
 
 Waliduje względem astro.com dla horoskopu referencyjnego.
 """
+import pytest
+
+from app.engine import houses as H
 from app.engine.chart import build_chart
 
 
@@ -66,3 +69,24 @@ def test_unknown_extra_system_is_ignored(own_engine, reference_moment):
     chart = build_chart(own_engine, reference_moment, "whole_sign",
                         house_systems=["placidus", "equal"])
     assert [h["system"] for h in chart["house_systems"]] == ["whole_sign", "equal"]
+
+
+@pytest.mark.parametrize("system", H.SYSTEMS)
+def test_every_advertised_system_builds_a_chart(own_engine, reference_moment, system):
+    """Każdy system z houses.SYSTEMS musi przejść przez build_chart. Pilnuje,
+    żeby rozszerzenie SYSTEMS bez przepięcia chart.py nie dało 500 przy wyborze
+    systemu, który jest na liście, ale nie w użytej funkcji."""
+    chart = build_chart(own_engine, reference_moment, system)
+    assert chart["house_system"] == system
+    assert len(chart["cusps"]) == 12
+    assert all(1 <= p["house"] <= 12 for p in chart["positions"])
+
+
+def test_multiple_systems_side_by_side_cover_all(own_engine, reference_moment):
+    chart = build_chart(own_engine, reference_moment, H.WHOLE_SIGN,
+                        house_systems=list(H.SYSTEMS))
+    blocks = chart["house_systems"]
+    assert blocks[0]["system"] == H.WHOLE_SIGN          # prymarny zawsze pierwszy
+    assert {b["system"] for b in blocks} == set(H.SYSTEMS)
+    for p in chart["positions"]:
+        assert set(p["houses"]) == set(H.SYSTEMS)