Address review: document deferred validation; test unknown-method behavior

- DataModel docstring: note that solver-side (C++) validation and dtype-cast
  warnings surface at Solve (lazy build), while structural checks stay eager
  at the setter (coderabbitai).
- test_lazy: lock that an unknown/typo'd method call (dm.random_func_call(...))
  raises AttributeError and is never recorded -- the recording layer installs
  only declared setters/getters, with no __getattr__ catch-all (Iroy30).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Ramakrishna Prabhu <ramakrishnap@nvidia.com>

Author: ramakrishnap-nv

python/cuopt/cuopt/routing/vehicle_routing.py

@@ -51,6 +51,12 @@ class DataModel(_LazyDataModel):
         host (numpy/pandas) inputs are copied to the device for the local
         solve. Python lists and tuples are not supported.
 
+      - Inputs are recorded and the device model is built lazily, so
+        solver-side (C++) validation and dtype-cast warnings surface when the
+        model is built -- at ``Solve`` -- rather than at the individual setter
+        call. Structural checks (matrix shape, array sizes, value ranges) are
+        still validated eagerly at the setter.
+
     Examples
     --------
     >>> from cuopt import routing

python/cuopt/cuopt/tests/routing/test_lazy.py

@@ -1,6 +1,8 @@
 # SPDX-FileCopyrightText: Copyright (c) 2026, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 # SPDX-License-Identifier: Apache-2.0
 
+import pytest
+
 from cuopt import routing
 from cuopt.routing import vehicle_routing_wrapper
 from cuopt.routing._lazy import _SKIP_GETTERS
@@ -25,3 +27,15 @@ def test_lazy_covers_wrapper_surface():
         f"lazy build layer does not handle wrapper methods {missing}; "
         "add a recorder/getter or list them in _SKIP_GETTERS"
     )
+
+
+def test_unknown_method_is_not_recorded():
+    """A call to a method that is not part of the DataModel surface raises
+    AttributeError rather than being silently recorded. The recording layer
+    installs only the declared setters/getters (no ``__getattr__`` catch-all),
+    so a typo'd or unknown call fails loudly and never enters the IR.
+    """
+    dm = routing.DataModel(3, 1)
+    with pytest.raises(AttributeError):
+        dm.random_func_call(1, 2, 3)
+    assert dm._calls == []