Cairo 1.x storage schema change and unresolved rollback safety

Cairo 1.x storage schema change and unresolved rollback safety

The goal is to determine whether contract storage can be safely rolled back to a previous layout after a storage schema change in Cairo 1.x. Sierra compilation enforces memory safety and bounded computation, but it does not define database-style schema migration or transactional rollback of contract storage.

The Cairo language specification assumes Cairo 1.x and the StarkNet storage model, and it does not document a standard on-chain upgrade or rollback pattern after storage fields are added, removed, or reordered. Whether Sierra safety assertions extend to application-level state is not addressed by the specification.

Is storage rollback safe after a schema change in Cairo 1.x? Which Sierra assertions cover storage schema migration? What on-chain pattern is intended when storage layout changes?