diff --git a/tests/test_loop.py b/tests/test_loop.py
index 90d45d8..48522d2 100644
--- a/tests/test_loop.py
+++ b/tests/test_loop.py
@@ -483,6 +483,169 @@ def test_parameters(X_n120) -> None:
     )
 
 
+def test_public_api_contract(X_n120) -> None:
+    """
+    Guards against unintentional breaking changes to the public API of
+    LocalOutlierProbability. Exercises every non-underscored constructor
+    keyword argument, every fit() keyword argument, public method, and
+    public attribute so that a rename or removal of any of them causes this
+    test to fail. Additions to the API are unaffected.
+
+    Written against the 1.0.0 scikit-learn-style API: the constructor takes
+    configuration only, data goes to ``fit(X, y=None, ...)``, and fitted
+    state lives on ``_``-suffixed attributes (with read-only legacy aliases).
+    :param X_n120: A pytest Fixture that generates 120 observations.
+    :return: None
+    """
+    # exercise every public constructor keyword argument by name; a rename
+    # or removal raises a TypeError here. Data parameters are no longer
+    # constructor arguments in 1.0.0 -- they are exercised via fit() below.
+    clf = loop.LocalOutlierProbability(
+        extent=3,
+        n_neighbors=10,
+        use_numba=NUMBA,
+        n_jobs=1,
+        progress_bar=False,
+    )
+
+    # sklearn contract: get_params() exposes exactly the constructor's
+    # parameters -- the configuration parameters plus the deprecated data
+    # keywords, which stay constructor arguments (with a FutureWarning)
+    # until they are removed in a future version
+    assert set(clf.get_params()) == {
+        "extent",
+        "n_neighbors",
+        "use_numba",
+        "n_jobs",
+        "progress_bar",
+        "data",
+        "distance_matrix",
+        "neighbor_matrix",
+        "cluster_labels",
+    }
+
+    # exercise every public method by name, and every fit() keyword
+    # argument by name (a rename or removal raises a TypeError here)
+    assert hasattr(clf, "fit") and callable(clf.fit)
+    fitted = clf.fit(
+        X_n120,
+        y=None,
+        distance_matrix=None,
+        neighbor_matrix=None,
+        cluster_labels=None,
+    )
+    assert fitted is clf
+    for method_name in (
+        "fit",
+        "fit_predict",
+        "predict",
+        "decision_function",
+        "score_samples",
+        "stream",
+        "get_params",
+        "set_params",
+    ):
+        assert hasattr(fitted, method_name) and callable(
+            getattr(fitted, method_name)
+        ), f"missing public method: {method_name}"
+    fitted.stream(X_n120[0])
+    fitted.predict(X_n120)
+    fitted.decision_function(X_n120)
+    fitted.score_samples(X_n120)
+
+    # every public (non-underscored) attribute expected to exist post-fit:
+    # configuration parameters, the deprecated constructor data inputs,
+    # the `_`-suffixed fitted state, and the read-only legacy aliases
+    expected_public_attributes = [
+        # configuration parameters (constructor)
+        "extent",
+        "n_neighbors",
+        "use_numba",
+        "n_jobs",
+        "progress_bar",
+        # deprecated constructor data inputs (always present, None here)
+        "data",
+        "distance_matrix",
+        "neighbor_matrix",
+        "cluster_labels",
+        # fitted state (scikit-learn convention)
+        "data_",
+        "distance_matrix_",
+        "neighbor_matrix_",
+        "cluster_labels_",
+        "n_neighbors_",
+        "n_features_in_",
+        "offset_",
+        "points_vector_",
+        "prob_distances_",
+        "prob_distances_ev_",
+        "norm_prob_local_outlier_factor_",
+        "local_outlier_probabilities_",
+        "is_fit_",
+        # read-only legacy aliases for fitted output attributes
+        "points_vector",
+        "prob_distances",
+        "prob_distances_ev",
+        "norm_prob_local_outlier_factor",
+        "local_outlier_probabilities",
+        "is_fit",
+    ]
+    for attr_name in expected_public_attributes:
+        assert hasattr(fitted, attr_name), f"missing public attribute: {attr_name}"
+
+    # the legacy aliases must read the canonical fitted attributes
+    assert fitted.local_outlier_probabilities is fitted.local_outlier_probabilities_
+    assert fitted.is_fit is fitted.is_fit_
+
+    # exercise every public constructor argument positionally, in the
+    # documented 1.0.0 order, using a distinct value per slot. Swapping two
+    # parameters of the same type (e.g. extent/n_neighbors/n_jobs, or
+    # use_numba/progress_bar) doesn't raise an error -- it silently
+    # assigns the wrong value -- so each assigned attribute is checked
+    # against the value passed at its expected position.
+    positional_clf = loop.LocalOutlierProbability(2, 15, False, 1, True)
+    assert positional_clf.extent == 2
+    assert positional_clf.n_neighbors == 15
+    assert positional_clf.use_numba is False
+    assert positional_clf.n_jobs == 1
+    assert positional_clf.progress_bar is True
+
+    # data is positional in fit(), sklearn-style: fit(X, y)
+    positional_fit = loop.LocalOutlierProbability(n_neighbors=10).fit(
+        X_n120, None
+    )
+    assert positional_fit.data_ is X_n120
+    assert positional_fit.is_fit_ is True
+
+    # the `LoOP` alias is part of the public API
+    from PyNomaly import LoOP
+
+    assert LoOP is loop.LocalOutlierProbability
+    assert loop.LoOP is loop.LocalOutlierProbability
+
+    # the exception hierarchy is part of the public API: customers import
+    # these names directly (as this test file does at the top) and may
+    # catch on the base classes, so both the import paths and the
+    # hierarchy itself must remain stable. The canonical home is
+    # PyNomaly.exceptions; PyNomaly.loop and PyNomaly re-export them.
+    from PyNomaly import exceptions
+    from PyNomaly.loop import (
+        PyNomalyError,
+        ValidationError,
+        ClusterSizeError as ImportedClusterSizeError,
+        MissingValuesError as ImportedMissingValuesError,
+    )
+
+    assert PyNomalyError is exceptions.PyNomalyError
+    assert ValidationError is exceptions.ValidationError
+    assert ImportedClusterSizeError is exceptions.ClusterSizeError
+    assert ImportedMissingValuesError is exceptions.MissingValuesError
+    assert issubclass(ImportedClusterSizeError, ValidationError)
+    assert issubclass(ImportedMissingValuesError, ValidationError)
+    assert issubclass(ValidationError, PyNomalyError)
+    assert issubclass(PyNomalyError, Exception)
+
+
 def test_n_neighbors() -> None:
     """
     Tests the functionality of providing a large number of neighbors that