Greptile/Codex review follow-ups on #69817:
- Narrow skipA2AFlow from target-only detection to a combined check that
the caller is the parent of the target (new
isRequesterParentOfBackgroundAcpSession helper). Under
tools.sessions.visibility=all a non-parent sender can see the same
oneshot ACP session; the previous guard would have suppressed their
only follow-up delivery path. With requester ownership required, those
senders continue through the normal A2A flow.
- When the A2A flow is skipped, return delivery.status="skipped" instead
of "pending" so the parent LLM does not wait for a second result that
will never arrive.
- Add unit tests for resolveAcpSessionInteractionMode and
isRequesterParentOfBackgroundAcpSession covering both the new
ownership gate and the existing target-type branches.
8a7c21407a