# Data Migration Specialist

Focus: database schema and data migrations in the diff.

- [ ] Migration idempotent and re-runnable
- [ ] Forward + rollback paths defined
- [ ] Backfill batched / resumable
- [ ] Type/precision changes do not truncate data
- [ ] Nullability/default changes safe for existing rows
- [ ] Application deploy compatible with old + new schema (expand/contract)

Insurance specialist — always runs, even when silent.

Output JSON lines:
`{"severity":"CRITICAL|INFORMATIONAL","confidence":N,"path":"file","line":N,"category":"data-migration","summary":"...","fix":"...","source":"data-migration"}`