…hine

Refactor GraphBuilder from a Python class using _MembersNeededForFinalize
to a cdef class with explicit _BuilderKind (PRIMARY/FORKED/CONDITIONAL_BODY)
and _CaptureState (NOT_STARTED/CAPTURING/ENDED) tracking. Cleanup moves
into __dealloc__/close, and the builder now uses GraphHandle/StreamHandle
from _resource_handles instead of holding raw driver objects. Drop the
is_stream_owner flag now that StreamHandle owns the lifetime.

End-capture paths in __dealloc__ and close guard on _h_stream so cleanup
is safe even if _init* fails before completing assignment.

Made-with: Cursor

… cycle

cimport-ing GraphBuilder at the top of _stream.pyx and _device.pyx made
Cython emit a Python-level import of cuda.core.graph._graph_builder
during _stream module init. That triggered the chain
graph -> _graph_node -> _kernel_arg_handler -> _memory._buffer
-> _device, which then re-entered the still-initializing _stream module
via "from cuda.core._stream import IsStreamT", failing with
ImportError: cannot import name IsStreamT.

Restore the original lazy "import GraphBuilder" inside
create_graph_builder (Stream and Device) and Stream_accept. The return
annotations stay as bare names; "from __future__ import annotations" in
both files defers their evaluation, so they need not resolve at
function-definition time.

Made-with: Cursor

The previous import-cycle fix changed _stream/_device.create_graph_builder
to a lazy Python "import GraphBuilder" instead of a module-level cimport.
With _init declared as @staticmethod cdef, Python attribute lookup
cannot find it, so every test that builds a graph failed with
"AttributeError: type object 'GraphBuilder' has no attribute '_init'"
at _device.pyx:1376 / _stream.pyx:376.

Convert _init from @staticmethod cdef to @staticmethod def (matches the
Stream._init pattern) and drop the cdef declaration from the .pxd.
_init runs once per builder creation, so the loss of cdef-level
dispatch is irrelevant. Graph._init stays cdef; it is only called
intra-module.

Made-with: Cursor