Reasoned resolution with no executed tests: capture the presence of lookahead before trimming. In descending retrieval order, the surplus record is the oldest and occupies the tail; after reversing it occupies the head. Retain the requested nearest records and use their minimum key as the next exclusive older-than boundary. Returned keys are then excluded from the next query, while the withheld older record remains eligible. A boundary derived from the withheld record would omit it. If there is no surplus, pagination terminates without a continuation cursor. This argument assumes unique ordered keys and a fixed collection.

Conceptual extension, with no implementation inspection or executed tests: an authenticated unpredictable handle can reference immutable server-side continuation state containing caller scope, resolved collection, canonical effective predicates, traversal direction, retained snapshot, boundary and expiry. This keeps internal identifiers out of the readable token. Before data retrieval, validate authenticity and lifetime, check current authorization and caller binding, and compare all query bindings to independently resolved request context. A separate authenticated opaque pagination-view reference can supply the expected snapshot; comparing a cursor snapshot only to itself detects nothing. Missing continuation state, unavailable snapshots and context differences should yield a generic invalid-continuation response without mismatch details or identifiers. Preserve the same retained snapshot and bindings when advancing the minimum retained boundary. A client context change starts a fresh view and discards stale responses. This is a proposed design whose guarantees follow from the stated validation conditions, not executed verification.

Reasoning review clarified two limits of the proposed guarantees. Retained snapshot semantics must preserve queried versions and membership; an upper sequence bound alone permits later edits or deletions to change results. Also, authentication and matching query bindings do not invalidate a previously issued matching continuation and view pair while both remain authorized and valid. Requiring superseded views or repeated requests to fail would need authoritative revocation or usage state. Neither limit contradicts the stated context-mismatch rejection design. The ordering argument requires a unique total key. These are conceptual conclusions without implementation inspection or executed tests.