diff --git a/docs/BUG_HISTORY.md b/docs/BUG_HISTORY.md
index 2650c216..cc627d5f 100644
--- a/docs/BUG_HISTORY.md
+++ b/docs/BUG_HISTORY.md
@@ -36593,3 +36593,18 @@
 - 相关记录：无。
 - 复发自：无。
 - 修复版本：分支 `codex/upstream-sync8-20261017`。上游提交 `e7301feb`、`86935c0a`、`4f1536f2`。
+
+## BUG-1387 | Saham 的 +30° 例外看错了操作数
+
+- 状态：resolved
+- 首次发现 / 最近更新：2026-10-17 / 2026-10-18
+- 来源：issue #80，任务书 T9。上游 `ce9fed15`。检索「add_30_degrees」「Punya_Saham」，无既有编号。
+- 现象：公式 Saham 在上升不落在第一操作数到第二操作数的顺行弧上时加 30°。规则文件七条公式的第三项都是上升，所以大量结果和 PVR 的判法差 30°。
+- 触发条件：`_calc_formula_saham`。本仓原先没有 trace 入口。
+- 根因：例外检查的是上升是否落在 A→B，PVR §28.8.1 检查的是第三操作数 C 是否落在 B→A。
+- 修复：两个入口都改为 `(C - B) % 360 <= (A - B) % 360`，不满足则结果加 30°。`references/saham_rules.json` 的描述改为同一条。补上 `_formula_saham_trace`，与数值入口使用同一判法。
+- 验证：`tests/test_saham_directed_operand_contract.py`。`tests/test_tajika.py` 三处断言按三栏改过：Punya 原值 85 / 新值 115；Karma 原值 40 / 新值 70；跨零点例子原值 340 / 新值 310。年运快照测试没有锁这三条公式的旧经度。
+- 防复发：契约测试覆盖 C 不是上升的公式，以及 trace 与数值入口一致。
+- 相关记录：无。
+- 复发自：无。
+- 修复版本：分支 `codex/upstream-sync8-20261017`。上游提交 `ce9fed15`。
diff --git a/references/saham_rules.json b/references/saham_rules.json
index 3e6c87a2..0f90dd94 100644
--- a/references/saham_rules.json
+++ b/references/saham_rules.json
@@ -46,6 +46,6 @@
     }
   },
   "exception_rules": {
-    "add_30_degrees": "If the Ascendant does not fall between the first and the second point in the zodiacal order, add 30 degrees (1 sign) to the final result."
+    "add_30_degrees": "For A - B + C, add 30 degrees when C does not lie on the forward zodiacal arc from B to A. PVR Integrated Approach section 28.8.1, source page 394."
   }
 }
diff --git a/scripts/tajika.py b/scripts/tajika.py
index 73a5dc5c..f99ef5f9 100644
--- a/scripts/tajika.py
+++ b/scripts/tajika.py
@@ -96,14 +96,36 @@ def _calc_formula_saham(
     second = _resolve_saham_operand(formula[1], planet_lons, asc_lon, computed)
     third = _resolve_saham_operand(formula[2], planet_lons, asc_lon, computed)
     result = (third + (first - second)) % 360
-    # references/saham_rules.json: add one sign when Ascendant is not on the
-    # forward zodiacal arc from the first formula point to the second.
-    ascendant_between_points = (
-        first <= asc_lon <= second
-        if first <= second
-        else asc_lon >= first or asc_lon <= second
-    )
-    return result if ascendant_between_points else (result + 30.0) % 360
+    # PVR §28.8.1, p394: in A-B+C, C must lie on the forward arc B -> A.
+    third_between_points = (third - second) % 360 <= (first - second) % 360
+    return result if third_between_points else (result + 30.0) % 360
+
+
+def _formula_saham_trace(
+    rule_name: str,
+    planet_lons: Dict[str, float],
+    asc_lon: float,
+    is_day: bool,
+    computed: Dict[str, float],
+) -> Dict:
+    """Calculate a rule-backed Saham while preserving its sensitive convention."""
+    rule = _SAHAM_RULES['sahams'][rule_name]
+    formula = rule['formula_day'] if is_day else rule['formula_night']
+    first = _resolve_saham_operand(formula[0], planet_lons, asc_lon, computed)
+    second = _resolve_saham_operand(formula[1], planet_lons, asc_lon, computed)
+    third = _resolve_saham_operand(formula[2], planet_lons, asc_lon, computed)
+    base_longitude = (third + (first - second)) % 360
+    third_between_points = (third - second) % 360 <= (first - second) % 360
+    exception_applied = not third_between_points
+    return {
+        'longitude': (base_longitude + 30.0) % 360 if exception_applied else base_longitude,
+        'base_longitude': base_longitude,
+        'rule_name': rule_name,
+        'formula_operands': formula,
+        'formula_variant': 'day' if is_day else 'night',
+        'zodiacal_order_exception_applied': exception_applied,
+        'rule_source': 'references/saham_rules.json',
+    }
 
 
 def calc_muntha(birth_asc_idx: int, age: int) -> Dict:
diff --git a/tests/test_saham_directed_operand_contract.py b/tests/test_saham_directed_operand_contract.py
new file mode 100644
index 00000000..127f3d7e
--- /dev/null
+++ b/tests/test_saham_directed_operand_contract.py
@@ -0,0 +1,26 @@
+import pytest
+from scripts import tajika
+
+
+@pytest.mark.parametrize('sun,moon,asc,expected,exception', [
+    (45, 120, 10, 115, True),
+    (45, 120, 60, 135, False),
+    (200, 100, 50, 310, False),
+    (200, 100, 150, 80, True),
+])
+def test_punya_matches_pvr_directed_arc(sun, moon, asc, expected, exception):
+    points = {'Sun': sun, 'Moon': moon}
+    assert tajika._calc_formula_saham('Punya_Saham', points, asc, True, {}) == expected
+    result = tajika._formula_saham_trace('Punya_Saham', points, asc, True, {})
+    assert result['longitude'] == expected
+    assert result['zodiacal_order_exception_applied'] is exception
+
+
+def test_third_operand_is_used_even_when_not_ascendant(monkeypatch):
+    monkeypatch.setitem(tajika._SAHAM_RULES['sahams'], 'TestThird', {
+        'formula_day': ['Jupiter', 'Moon', 'Venus'],
+        'formula_night': ['Moon', 'Jupiter', 'Venus'],
+    })
+    points = {'Jupiter': 200., 'Moon': 50., 'Venus': 100.}
+    assert tajika._calc_formula_saham('TestThird', points, 60., True, {}) == 250.
+    assert tajika._calc_formula_saham('TestThird', points, 60., False, {}) == 340.
diff --git a/tests/test_tajika.py b/tests/test_tajika.py
index d21667d9..5afbb228 100644
--- a/tests/test_tajika.py
+++ b/tests/test_tajika.py
@@ -285,7 +285,8 @@ class TestSahams:
     def test_punya_saham_formula(self):
         # Punya = Asc + (Moon - Sun), sourced from references/saham_rules.json
         sun, moon, asc = 45.0, 120.0, 10.0
-        expected = (asc + (moon - sun)) % 360  # = 10 + 75 = 85
+        # 原值 85 / 新值 115 / 原因：C=Asc10 不在 B=Sun45 → A=Moon120 的顺行弧上，按 PVR p394 加 30°。
+        expected = 115.0
         planet_lons = {'Sun': sun, 'Moon': moon, 'Mars': 90.0,
                        'Mercury': 60.0, 'Jupiter': 180.0, 'Venus': 210.0,
                        'Saturn': 300.0, 'Rahu': 150.0, 'Ketu': 330.0}
@@ -298,14 +299,15 @@ class TestSahams:
         planet_lons = {'Sun': 45.0, 'Moon': 120.0, 'Mars': 90.0,
                        'Mercury': 60.0, 'Jupiter': 180.0, 'Venus': 210.0,
                        'Saturn': 300.0, 'Rahu': 150.0, 'Ketu': 330.0}
-        expected = (asc + (90.0 - 60.0)) % 360
+        # 原值 40 / 新值 70 / 原因：C=Asc10 不在 B=Mercury60 → A=Mars90 的顺行弧上，加 30°。
+        expected = 70.0
         result = calc_all_sahams(planet_lons, asc, datetime(1990, 6, 15, 12, 0), lat=39.9042, lon=116.4074, tz=8)
         assert abs(result['karma_saham']['longitude'] - expected) < 0.01
 
     def test_formula_saham_applies_reference_add_30_exception(self):
         from tajika import _calc_formula_saham
 
-        # Asc 50 is outside the forward 100 -> 200 zodiacal arc.
+        # 原值 340 / 新值 310 / 原因：C=Asc50 落在 B=Sun200 → A=Moon100 的跨零点顺行弧上，不加 30°。
         result = _calc_formula_saham(
             'Punya_Saham',
             {'Sun': 200.0, 'Moon': 100.0},
@@ -313,7 +315,7 @@ class TestSahams:
             True,
             {},
         )
-        assert result == 340.0
+        assert result == 310.0
 
     def test_is_faster_moon_vs_sun(self):
         assert _is_faster('Moon', 'Sun')