Data migration is not just a technical handover. It is the moment every figure in the system has to land in the right place or the accounts do not balance. For NZRT that means two tracks: commercial income (API, ICS, ITE) and charitable expenditure (NCS). Before any migration wave runs, both tracks need to be reconciled to zero variance against the source system. An unreconciled entry in transit is invisible, and invisible errors compound. Once the wave closes you cannot easily trace where the gap opened.
The Migration Planning doc covers wave sequencing and rollback. The transition architectures define what the interim state looks like. The interim state is the risk period from a finance perspective. During parallel run, both source and target hold live data. Any transaction posted to the wrong system in that window creates a reconciliation problem that is hard to trace after cutover. The data migration strategy needs to be explicit about which system holds the ledger at each stage, and what the reconciliation checkpoint looks like before the source goes read-only. That checkpoint is the gate. If the figures do not match, the wave does not proceed. Migration planning doc: https://cloud.nzrtnetwork.com/nextcloud/index.php/s/zqgqF8PPAJnpkem - Transition architectures: https://cloud.nzrtnetwork.com/nextcloud/index.php/s/gcJdZkWe8XCoXki
