Escalation between two Operators is enqueue-and-continue, never stop-and-wait. When Operator A stalls on a node, it enqueues that node and returns to its own partition; whichever Operator frees up first steals the queued item and retries it fresh — different temperature, different draw, decorrelated by construction.
Every enqueue, steal, and resolution is a ledger row. If the late resolution has upstream effects, RHA's normal re-sweep over the forward dependency pointers catches them — the substrate reconciles what concurrency defers. I/O discipline: the two Operators are never serialized against each other.