# Data Migration — Manual Review Checklist

High-risk module: schema/data migration requires human confirmation.

- [ ] Migration is idempotent and re-runnable
- [ ] Forward and rollback paths both defined and tested
- [ ] Backfill is batched / resumable for large tables
- [ ] Data type / precision changes do not silently truncate
- [ ] Nullability and default changes safe for existing rows
- [ ] Migration ordering across shards / replicas is consistent
- [ ] Application deploys compatibly with both old and new schema (expand/contract)
- [ ] Irreversible operations are flagged with a documented reason