@@ -170,7 +170,7 @@ class StridedMemoryView:
         individual keyword arguments directly, or provide bundled tiled
         options via ``options=``.
         """
-    def copy_from(self, other: StridedMemoryView, stream: Stream, allocator: object | None=None, blocking: bool | None=None) -> None:
+    def copy_from(self, other: StridedMemoryView, stream: Stream | None, allocator: object | None=None, blocking: bool | None=None) -> None:
         """
         Copies the data from the other view into this view.
 
 
@@ -419,7 +419,7 @@ cdef class StridedMemoryView:
     def copy_from(
         self,
         StridedMemoryView other not None: StridedMemoryView,
-        stream not None: Stream,
+        stream: Stream | None,
         allocator: object = None,
         blocking: bool | None = None,
     ) -> None:
 
@@ -23,7 +23,7 @@ class AdjacencySetProxy(MutableSet[GraphNode]):
     def __iter__(self) -> Iterator[GraphNode]: ...
     def __len__(self) -> int: ...
     def add(self, value: GraphNode) -> None: ...
-    def discard(self, value: GraphNode) -> None: ...
+    def discard(self, value: object) -> None: ...
     def clear(self) -> None:
         """Remove all edges in a single driver call."""
     def __isub__(self, it: Set[Any]) -> AdjacencySetProxy:
 
@@ -15,7 +15,6 @@ 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
 
@@ -60,8 +59,8 @@ class AdjacencySetProxy(MutableSet[GraphNode]):
             return
         (<_AdjacencySetCore>self._core).add_edge(<GraphNode>value)
 
-    @cython.annotation_typing(False)
-    def discard(self, GraphNode value not None: GraphNode) -> None:
+    def discard(self, value: object) -> None:
+        # Non-GraphNode values are a no-op, matching MutableSet semantics.
         (<_AdjacencySetCore>self._core).check_owner_mutable()
         if value not in self:
             return
 
@@ -47,6 +47,24 @@ def test_conditional_rejects_non_condition(init_cuda, method, args):
         getattr(g, method)(*args)
 
 
+@pytest.mark.agent_authored(model="claude-sonnet-5-5")
+@pytest.mark.parametrize("none_arg", ["config", "kernel"])
+@pytest.mark.parametrize("target", ["GraphDefinition", "GraphNode"])
+def test_launch_rejects_none(init_cuda, target, none_arg):
+    """launch() on a graph or node rejects None for config and kernel."""
+    kernel = compile_common_kernels().get_kernel("add_one")
+    g = GraphDefinition()
+    if target == "GraphDefinition":
+        owner = g
+    else:
+        owner = g.empty()
+    args = {"config": LaunchConfig(grid=1, block=1), "kernel": kernel}
+    args[none_arg] = None
+
+    with pytest.raises(TypeError):
+        owner.launch(args["config"], args["kernel"])
+
+
 def test_embed_rejects_non_graphdef(init_cuda):
     """embed() rejects non-GraphDefinition arguments."""
     g = GraphDefinition()
 
@@ -46,6 +46,17 @@ def pinned_mr():
     return LegacyPinnedMemoryResource()
 
 
+@pytest.mark.agent_authored(model="claude-sonnet-5-5")
+def test_copy_from_rejects_none_src(single_copy_device, single_copy_stream, pinned_mr):
+    """copy_from(None) raises TypeError instead of dereferencing a null source."""
+    dst = pinned_mr.allocate(SIZE)
+
+    with pytest.raises(TypeError):
+        dst.copy_from(None, stream=single_copy_stream)
+
+    dst.close()
+
+
 @pytest.mark.agent_authored(model="Claude Sonnet 4.6")
 @thread_unsafe_on_windows
 def test_options_none_copy_to_data_correct(single_copy_device, single_copy_stream, pinned_mr):
 
@@ -494,6 +494,20 @@ def test_launch_cluster_scheduling_policy_smoke(init_cuda):
     stream.sync()
 
 
+@pytest.mark.agent_authored(model="claude-sonnet-5-5")
+@pytest.mark.parametrize("none_arg", ["config", "kernel"])
+def test_launch_rejects_none(init_cuda, none_arg):
+    """None for a cdef-class argument raises TypeError instead of reaching C."""
+    program = Program('extern "C" __global__ void my_kernel() {}', SourceCodeType.CXX)
+    ker = program.compile(ObjectCodeFormatType.CUBIN).get_kernel("my_kernel")
+    config = LaunchConfig(grid=(1, 1, 1), block=(1, 1, 1))
+    args = {"config": config, "kernel": ker}
+    args[none_arg] = None
+
+    with pytest.raises(TypeError):
+        launch(Device().create_stream(), args["config"], args["kernel"])
+
+
 def test_launch_invalid_values(init_cuda):
     code = 'extern "C" __global__ void my_kernel() {}'
     program = Program(code, SourceCodeType.CXX)