# Schema Migration with Backfill (fs_004)

## Objective
Add normalized address schema, migrate legacy rows with backfill job, dual-read/write transition, and rollback script.

## Language & Library Constraints
- Primary language: java
- Available libraries: spring-boot, jooq, flyway
- Prefer explicit use of selected library APIs in task execution contracts.

## Required Artifacts
- db/migrations/*
- service/address/*
- jobs/backfill/*
- rollback/*.sql
- tests/migration/*

## Acceptance
- Generate deterministic taskitems with strict execution contracts.
- Include selected library and preferred APIs per task where applicable.