fence
Records a completion fence after all GPU work issued so far on the device queue.
An initialization fence protects work issued by target allocation, a capture fence protects a source lease, and a distinct fence issued after GUI consumption protects target reuse. Implementations issue no explicit completion wait and must preserve the host's required submission boundaries. A backend may submit when its host contract requires it, but a shared host encoder must remain in the current frame submission.
Return
an exclusively owned nonblocking completion probe.
Throws
when fence creation or a required submission fails; the caller quarantines potentially used resources until device shutdown.