plan data platform migration covering scope and what is deliberately retired rather than carried, dual-run design, parity reconciliation across row counts control totals and metric values with a stated tolerance, historical backfill depth, consumer cutover sequencing, query translation risk in type coercion null handling timezone and rounding, freeze windows, cutover and rollback, and the decommission gate for the legacy platform. use for warehouse migration, lakehouse moves, engine changes, and legacy retirement.
