diff --git a/scripts/jyotish_engine.py b/scripts/jyotish_engine.py
index c724536a..166d34c0 100644
--- a/scripts/jyotish_engine.py
+++ b/scripts/jyotish_engine.py
@@ -15532,12 +15532,11 @@ def cmd_full_reading(args):
             pada = _padas.get(key)
             if not pada:
                 return {"error": f"jaimini.calc_arudha_padas 未给出 {key}"}
-            lord_deg = planet_lons.get(pada['source_house_lord'], 0)
-            degree = (pada['sign_idx'] * 30 + (lord_deg % 30)) % 360
             return {
-                "degree": round(degree, 4),
+                "degree": None,
+                "coordinate_basis": "sign_only_arudha",
                 "sign": pada['sign'],
-                "sign_degree": round(degree % 30, 4),
+                "sign_degree": None,
                 "house": ((pada['sign_idx'] - asc_idx) % 12) + 1,
                 "distance_from_source": pada['distance'],
                 "exception_applied": pada['exception_triggered'],
diff --git a/scripts/special_lagnas.py b/scripts/special_lagnas.py
index e8c2f550..4f028c80 100644
--- a/scripts/special_lagnas.py
+++ b/scripts/special_lagnas.py
@@ -254,13 +254,14 @@ class SpecialLagnasCalculator:
             pada_sign = (pada_sign + 9) % 12
             exception_applied = True
 
-        pada_degree = (pada_sign * 30 + (source_lord_degree % 30)) % 360
+        # Sign counting determines a sign, not a longitude inside that sign.
         return {
             "label": label,
             "source_house": source_house,
-            "degree": round(pada_degree, 4),
+            "degree": None,
+            "coordinate_basis": "sign_only_arudha",
             "sign": self.SIGNS[pada_sign],
-            "sign_degree": round(pada_degree % 30, 4),
+            "sign_degree": None,
             "house": ((pada_sign - asc_sign) % 12) + 1,
             "source_sign": self.SIGNS[source_sign],
             "source_lord_sign": self.SIGNS[lord_sign],
@@ -284,6 +285,10 @@ class SpecialLagnasCalculator:
             lines.append(f"{lagna_name}:")
             if "note" in data:
                 lines.append(f"  {data['note']}")
+            elif data.get("coordinate_basis") == "sign_only_arudha":
+                lines.append(f"  Position: {data['sign']} (sign-level result); house {data['house']}")
+                lines.append(f"  Formula: {data['formula']}")
+                lines.append(f"  Meaning: {data['meaning']}")
             else:
                 lines.append(f"  Position: {data['sign']} {data['sign_degree']:.2f}° ({data['degree']:.2f}°)")
                 lines.append(f"  Formula: {data['formula']}")
diff --git a/tests/test_upstream_sync9_special_lagnas_arudha_coordinates.py b/tests/test_upstream_sync9_special_lagnas_arudha_coordinates.py
new file mode 100644
index 00000000..f378b85a
--- /dev/null
+++ b/tests/test_upstream_sync9_special_lagnas_arudha_coordinates.py
@@ -0,0 +1,30 @@
+"""Arudha counting yields a sign, not a fabricated intra-sign longitude.
+
+Upstream calls calculate_arudha_lagna / calculate_upapada_lagna. This tree's
+names are calculate_arudha_pada (house 1 and house 12) and calculate_a10.
+"""
+
+from scripts.special_lagnas import SpecialLagnasCalculator
+
+
+def test_arudha_outputs_are_explicitly_sign_level() -> None:
+    calculator = SpecialLagnasCalculator()
+    rows = (
+        calculator.calculate_arudha_pada(15.0, 1, 95.0),
+        calculator.calculate_a10(15.0, 215.0),
+        calculator.calculate_arudha_pada(15.0, 12, 305.0, "Upapada"),
+    )
+
+    for row in rows:
+        assert row["coordinate_basis"] == "sign_only_arudha"
+        assert row["degree"] is None
+        assert row["sign_degree"] is None
+
+
+def test_sign_level_arudha_is_not_rendered_as_a_degree() -> None:
+    calculator = SpecialLagnasCalculator()
+    arudha = calculator.calculate_arudha_pada(15.0, 1, 95.0)
+    rendered = calculator.format_output({"Arudha_Lagna": arudha})
+
+    assert "sign-level result" in rendered
+    assert "None°" not in rendered