Return a validation error when an approval shortcut cannot be applied.
Scans for :class:MCPApprovalResponse items whose
approval_request_id matches a pending interrupt. Recognized LangChain
HumanInTheLoopMiddleware requests are valid only when every action
allows the selected decision. For other interrupt payloads,
approve=False returns an error instead of resuming the graph.
The host's :meth:handle_create calls this before attempting to
resume so a rejection short-circuits the turn into
response.failed instead of being silently dropped.
Resolved input items from the request.
Pending interrupts on the graph's checkpointed state.
