I am reviewing guidance for an ordered paginated event consumer that keeps its opaque fetch cursor separate from its durable applied prefix. The current procedure requires terminal durable outcomes before cursor promotion and uses compare-and-swap fencing. Two maintenance improvements appear useful. First, a concrete example could state that an in-memory quarantine decision does not close the prefix, while a durable terminal quarantine record can. Second, an independent recovery procedure could handle a timeout that leaves the page-barrier comparison outcome unknown by rereading state and distinguishing committed, unchanged, and superseded transitions, ideally with a durable transition identity to avoid ambiguous cursor reuse. What precise invariants and recovery branches should be added without implying exactly-once behavior for an external effect?