diff --git a/dgamore/nonlocal_sde.py b/dgamore/nonlocal_sde.py
index e430f54..670d9cd 100644
--- a/dgamore/nonlocal_sde.py
+++ b/dgamore/nonlocal_sde.py
@@ -336,16 +336,24 @@ def fit_oz_spin(q_grid: KGrid, mat: np.ndarray):
     chi_mat = chi.map_to_full_bz(config.lattice.q_grid).to_half_niw_range().take_first_wn().mat.real
     orb_shape = (config.sys.n_bands,) * 4
     oz_coeffs = np.zeros(orb_shape + (2,), dtype=float)
+    failed_orbitals = []
 
     for idx in np.ndindex(orb_shape):
         mat_slice = chi_mat[..., idx[0], idx[1], idx[2], idx[3]].flatten()
         try:
             coeffs = fit_oz_spin(config.lattice.q_grid, mat_slice) if not np.all(mat_slice == 0) else [0.0, 0.0]
         except (ValueError, RuntimeError, opt.OptimizeWarning):
-            config.logger.warning(f"OZ fit did not converge for orbitals {idx}. Using [-1, -1].")
+            failed_orbitals.append(idx)
             coeffs = [-1.0, -1.0]
         oz_coeffs[idx] = coeffs
 
+    if failed_orbitals:
+        one_based = [tuple(o + 1 for o in idx) for idx in failed_orbitals]
+        config.logger.warning(
+            f"OZ fit did not converge for {len(failed_orbitals)} orbital combination(s): "
+            f"{one_based}. Using [-1, -1]."
+        )
+
     rows = []
     for idx in np.ndindex(orb_shape):
         rows.append([*idx, *oz_coeffs[idx]])
diff --git a/tests/test_nonlocal_sde.py b/tests/test_nonlocal_sde.py
index 8cd87b6..ebb6b67 100644
--- a/tests/test_nonlocal_sde.py
+++ b/tests/test_nonlocal_sde.py
@@ -6,15 +6,17 @@
 
 import itertools
 import os
+from unittest import mock
 
 import numpy as np
 
 import dgamore.config as config
+import dgamore.nonlocal_sde as nonlocal_sde
 from dgamore.hamiltonian import Hamiltonian
 from dgamore.interaction import Interaction
 from dgamore.local_sde import get_local_hartree_fock
 from dgamore.n_point_base import SpinChannel
-from dgamore.nonlocal_sde import _init_mu_history, get_hartree_fock
+from dgamore.nonlocal_sde import _init_mu_history, get_hartree_fock, perform_ornstein_zernicke_fit
 
 LOCAL_SDE_DATA = f"{os.path.dirname(os.path.abspath(__file__))}/test_data/local_sde"
 
@@ -80,3 +82,55 @@ def test_nonlocal_hartree_fock_matches_local_reference():
     assert np.allclose(hf_nonlocal, sigma_hf_ref[None, ...])
     # the same reference is the local Hartree-Fock, so the two SDE paths agree
     assert np.allclose(hf_nonlocal, get_local_hartree_fock(u_loc, occ)[None, ...])
+
+
+class _ConstantChi:
+    """Minimal physical-susceptibility stand-in whose BZ and frequency reductions are identities."""
+
+    def __init__(self, mat: np.ndarray):
+        """Stores the orbital-resolved matrix that the reduction chain returns unchanged."""
+        self._mat = mat
+
+    def map_to_full_bz(self, grid):
+        """Identity unfolding to the full BZ."""
+        return self
+
+    def to_half_niw_range(self):
+        """Identity reduction to the half niw range."""
+        return self
+
+    def take_first_wn(self):
+        """Identity selection of the first bosonic frequency."""
+        return self
+
+    @property
+    def mat(self) -> np.ndarray:
+        """The backing orbital-resolved matrix."""
+        return self._mat
+
+
+def test_ornstein_zernicke_fit_aggregates_nonconverged_warnings(monkeypatch):
+    """All non-converging OZ fits collapse into a single aggregated warning instead of one log per orbital."""
+    config.sys.n_bands = 2
+    logger = mock.Mock()
+    monkeypatch.setattr(config, "logger", logger, raising=False)
+    monkeypatch.setattr(nonlocal_sde.opt, "curve_fit", mock.Mock(side_effect=RuntimeError("forced non-convergence")))
+
+    perform_ornstein_zernicke_fit(_ConstantChi(np.ones((2, 2, 1, 2, 2, 2, 2), dtype=np.complex64)))
+
+    logger.warning.assert_called_once()
+    msg = logger.warning.call_args.args[0]
+    assert "16 orbital combination(s)" in msg
+    assert "(1, 1, 1, 1)" in msg and "(2, 2, 2, 2)" in msg  # 1-based orbital labels, not 0-based
+
+
+def test_ornstein_zernicke_fit_logs_no_warning_when_all_converge(monkeypatch):
+    """A fully converging set of OZ fits emits no warning at all (the aggregation guard stays silent)."""
+    config.sys.n_bands = 2
+    logger = mock.Mock()
+    monkeypatch.setattr(config, "logger", logger, raising=False)
+    monkeypatch.setattr(nonlocal_sde.opt, "curve_fit", mock.Mock(return_value=(np.array([1.0, 2.0]), None)))
+
+    perform_ornstein_zernicke_fit(_ConstantChi(np.ones((2, 2, 1, 2, 2, 2, 2), dtype=np.complex64)))
+
+    logger.warning.assert_not_called()