fix(cuda.core): preserve adjacency set semantics

cuda_core/cuda/core/graph/_adjacency_set_proxy.pyx

@@ -15,6 +15,7 @@ from cuda.core._rt cimport (
     graph_node_get_graph,
 )
 from cuda.core._utils.cuda_utils cimport HANDLE_RETURN
+import cython
 from collections.abc import Iterable, Iterator, MutableSet, Set
 from typing import Any, TypeVar
 
@@ -59,6 +60,7 @@ class AdjacencySetProxy(MutableSet[GraphNode]):
             return
         (<_AdjacencySetCore>self._core).add_edge(<GraphNode>value)
 
+    @cython.annotation_typing(False)
     def discard(self, value: GraphNode) -> None:
         (<_AdjacencySetCore>self._core).check_owner_mutable()
         if value not in self:

cuda_core/docs/source/release/1.3.0-notes.rst

@@ -129,3 +129,8 @@ Fixes and enhancements
   device is now revoked with its own request, so no single device can block
   the others.
   (`#2807 <https://github.com/NVIDIA/cuda-python/issues/2807>`__)
+
+- Calling ``discard()`` on the set-like :attr:`graph.GraphNode.pred` and
+  :attr:`graph.GraphNode.succ` views with an object that is not a
+  :class:`~graph.GraphNode` is now a no-op instead of raising ``TypeError``,
+  consistent with :class:`collections.abc.MutableSet` semantics.

cuda_core/tests/graph/test_graph_definition_mutation.py

@@ -389,6 +389,20 @@ def test_add_wrong_type(init_cuda):
         node.succ.add(42)
 
 
+@pytest.mark.agent_authored(model="gpt-5.6-sol")
+def test_discard_wrong_type_is_noop(init_cuda):
+    """Discarding a non-GraphNode is a no-op, matching MutableSet semantics."""
+    g = GraphDefinition()
+    owner = g.empty()
+    neighbor = g.empty()
+    owner.succ.add(neighbor)
+
+    owner.succ.discard("not a node")
+    owner.succ.discard(42)
+
+    assert owner.succ == {neighbor}
+
+
 @pytest.mark.agent_authored(model="gpt-5.6")
 def test_discard_absent_invalid_value_is_noop(init_cuda):
     graph = GraphDefinition()