仓库原始内容
按源仓库内容呈现，保留标题、案例、代码、表格、链接以及原文引用的演示图片。
Migration
Map current readers, writers, data shape, compatibility window, and ownership before editing.
- Define forward path and rollback path.
- Preserve existing data; make destructive steps explicit and separately authorized.
- Keep mixed-version operation safe where rollout can overlap.
- Sequence expand, migrate, verify, then contract when applicable.
- Make retries idempotent and partial failure observable.
- Verify old and new paths at required transition stages.
Stop after requested stage passes; do not perform later destructive contraction implicitly.
