diff --git a/src/alphajudge/interface.py b/src/alphajudge/interface.py
index 036aa16..485bcfd 100644
--- a/src/alphajudge/interface.py
+++ b/src/alphajudge/interface.py
@@ -174,6 +174,45 @@ def _lis_dir(idx_src: np.ndarray, idx_dst: np.ndarray) -> float:
         b = _lis_dir(self._idx2, self._idx1)
         return float(0.5 * (a + b))
 
+    def clis(self) -> float:
+        """
+        Contact-restricted LIS (cLIS): the LIS PAE transform averaged only over
+        residue pairs that are also in direct physical contact (representative
+        atom, CB-else-CA, within contact_thresh; default Cβ-Cβ <= 8 A). Both
+        chain directions are scored separately and averaged, mirroring lis().
+        Returns 0.0 when no contacts or no valid PAE pairs.
+        """
+        if not self._pairs:
+            return 0.0
+        ab: list[float] = []
+        ba: list[float] = []
+        for r1, r2 in self._pairs:
+            i = self._rim.get((r1.get_parent().id, r1.id))
+            j = self._rim.get((r2.get_parent().id, r2.id))
+            if i is None or j is None:
+                continue
+            p_ab = float(self._pae[i, j])
+            p_ba = float(self._pae[j, i])
+            if p_ab < 12.0:
+                ab.append((12.0 - p_ab) / 12.0)
+            if p_ba < 12.0:
+                ba.append((12.0 - p_ba) / 12.0)
+        a = float(np.mean(ab)) if ab else 0.0
+        b = float(np.mean(ba)) if ba else 0.0
+        return float(0.5 * (a + b))
+
+    def ilis(self) -> float:
+        """
+        Integrated LIS (iLIS = sqrt(LIS * cLIS); Kim et al., AFM-LIS). The
+        geometric mean forces the score to 0 unless the interface has both broad
+        PAE confidence (LIS) and confident direct contacts (cLIS).
+        """
+        lis = self.lis()
+        clis = self.clis()
+        if lis <= 0.0 or clis <= 0.0:
+            return 0.0
+        return float(math.sqrt(lis * clis))
+
     @property
     def polar(self) -> float:
         return self._frac(POLAR_RES)
diff --git a/src/alphajudge/runner.py b/src/alphajudge/runner.py
index dae9273..9b74441 100644
--- a/src/alphajudge/runner.py
+++ b/src/alphajudge/runner.py
@@ -117,6 +117,8 @@ def process(
                     "interface_pDockQ2": pd2,
                     "interface_ipSAE": iface.ipsae(),
                     "interface_LIS": iface.lis(),
+                    "interface_cLIS": iface.clis(),
+                    "interface_iLIS": iface.ilis(),
                 }
 
                 # Add expensive metrics only if not skipped
diff --git a/test/test_parsers_and_runner.py b/test/test_parsers_and_runner.py
index 0b10fa5..b4e15be 100644
--- a/test/test_parsers_and_runner.py
+++ b/test/test_parsers_and_runner.py
@@ -41,6 +41,8 @@
     "interface_pDockQ2",
     "interface_ipSAE",
     "interface_LIS",
+    "interface_cLIS",
+    "interface_iLIS",
     "interface_hb",
     "interface_sb",
     "interface_ss",
@@ -332,6 +334,62 @@ def test_af2_runner_outputs_have_expected_scores(tmp_path: Path, af2_dir_src: Pa
                     assert nearly_equal(got_iptm_ptm, float(exp_ptm)), f"AF2 monomer iptm_ptm should be NaN or ptm for {m}"
 
 
+class _FakeResidue:
+    """Minimal hashable Bio.PDB-like residue with .id and .get_parent().id."""
+
+    def __init__(self, chain_id: str, res_id: Any):
+        self.id = res_id
+        self._parent = type("_Chain", (), {"id": chain_id})()
+
+    def get_parent(self):
+        return self._parent
+
+
+def _make_residue(chain_id: str, res_id: Any) -> _FakeResidue:
+    return _FakeResidue(chain_id, res_id)
+
+
+def test_clis_ilis_math_is_deterministic():
+    """
+    cLIS restricts the LIS PAE transform to contacting residue pairs and iLIS is
+    the geometric mean sqrt(LIS * cLIS) (AFM-LIS, Kim et al.). Build a tiny 2+2
+    complex with a known PAE matrix so the arithmetic is checkable by hand.
+    """
+    from alphajudge.interface import Interface
+
+    a1, a2 = _make_residue("A", (" ", 1, " ")), _make_residue("A", (" ", 2, " "))
+    b1, b2 = _make_residue("B", (" ", 1, " ")), _make_residue("B", (" ", 2, " "))
+
+    # PAE indices: A1->0, A2->1, B1->2, B2->3. Intra-chain PAE is irrelevant.
+    pae = np.array(
+        [
+            [0.0, 0.0, 0.0, 6.0],
+            [0.0, 0.0, 24.0, 24.0],
+            [0.0, 24.0, 0.0, 0.0],
+            [6.0, 24.0, 0.0, 0.0],
+        ]
+    )
+
+    iface = object.__new__(Interface)  # bypass __init__; set only what we exercise
+    iface._pae = pae
+    iface._idx1 = np.array([0, 1])
+    iface._idx2 = np.array([2, 3])
+    iface._rim = {("A", a1.id): 0, ("A", a2.id): 1, ("B", b1.id): 2, ("B", b2.id): 3}
+    iface._pairs = {(a1, b1)}  # only A1-B1 is in physical contact
+
+    # LIS: A->B valid entries (12-pae)/12 = [1.0, 0.5]; B->A = [1.0, 0.5]; mean 0.75.
+    assert nearly_equal(iface.lis(), 0.75)
+    # cLIS: only the A1-B1 contact, pae 0 both directions -> 1.0.
+    assert nearly_equal(iface.clis(), 1.0)
+    # iLIS = sqrt(0.75 * 1.0).
+    assert nearly_equal(iface.ilis(), math.sqrt(0.75))
+
+    # No contacts -> cLIS 0 -> iLIS 0 regardless of LIS.
+    iface._pairs = set()
+    assert iface.clis() == 0.0
+    assert iface.ilis() == 0.0
+
+
 # -------------------------
 # AF3 runner: best/all + score checks
 # -------------------------