fix(models): seal model-spec record admission

docs/changelog.d/1063-model-spec-record-admission.md

@@ -0,0 +1,5 @@
+# Model-spec record admission
+
+## Fixed
+
+- Model resolution now admits only exact package-owned exploratory and confirmatory model records before reading their fields, so caller-defined model-spec subclasses cannot execute attribute callbacks during validation. Exact built-in/concrete NumPy factor counts and exact package model records retain their existing behavior; multidimensional exploratory estimation remains separately governed by #633.

python/fast_mlsirm/models.py

@@ -148,14 +148,14 @@ def _resolve_model(
         raise TypeError("model must be a factor count or an IRT model specification")
     if type(model) is int or _is_exact_numpy_integer_scalar(model):
         model = ExploratoryModel(model)
-    if isinstance(model, ExploratoryModel):
+    if type(model) is ExploratoryModel:
         if model.dimensions != 1:
             raise NotImplementedError(
                 "multidimensional exploratory loading estimation is not implemented; "
                 "use models.confirmatory(...) for an identified loading structure"
             )
         return model, np.ones((n_items, 1), dtype=np.int64)
-    if isinstance(model, ConfirmatoryModel):
+    if type(model) is ConfirmatoryModel:
         if model.loading_pattern.shape[0] != n_items:
             raise ValueError(
                 "confirmatory model must have one loading-pattern row per item"

tests/test_cov_a_models.py

@@ -185,6 +185,52 @@ class HostileNumpyInt(np.int64, metaclass=HostileMeta):
     assert calls == []
 
 
+def test_resolve_model_rejects_exploratory_subclass_before_attribute_callback():
+    """Reject exploratory subclasses before reading caller-controlled fields."""
+    calls: list[str] = []
+
+    class HostileExploratory(ExploratoryModel):
+        """Expose a hostile dimensions attribute on a caller subclass."""
+
+        def __getattribute__(self, name: str):
+            """Fail if model resolution reads caller-controlled dimensions."""
+            if name == "dimensions":
+                calls.append(name)
+                raise AssertionError("model attribute callback executed")
+            return super().__getattribute__(name)
+
+    spec = object.__new__(HostileExploratory)
+    object.__setattr__(spec, "dimensions", 1)
+
+    with pytest.raises(TypeError, match="factor count"):
+        _resolve_model(spec, 5)
+
+    assert calls == []
+
+
+def test_resolve_model_rejects_confirmatory_subclass_before_attribute_callback():
+    """Reject confirmatory subclasses before reading loading-pattern metadata."""
+    calls: list[str] = []
+
+    class HostileConfirmatory(ConfirmatoryModel):
+        """Expose a hostile loading-pattern attribute on a caller subclass."""
+
+        def __getattribute__(self, name: str):
+            """Fail if model resolution reads caller-controlled metadata."""
+            if name == "loading_pattern":
+                calls.append(name)
+                raise AssertionError("model attribute callback executed")
+            return super().__getattribute__(name)
+
+    spec = object.__new__(HostileConfirmatory)
+    object.__setattr__(spec, "loading_pattern", np.ones((5, 1), dtype=np.int64))
+
+    with pytest.raises(TypeError, match="factor count"):
+        _resolve_model(spec, 5)
+
+    assert calls == []
+
+
 def test_resolve_model_multidim_exploratory_not_implemented():
     with pytest.raises(NotImplementedError):
         _resolve_model(2, 6)