## 1. API contract and data handling

- [x] 1.1 Document the hierarchical node fields, relationship exceptions, and top-level pagination shell for package history.
- [x] 1.2 Add a client-side response normalizer that preserves recursively returned `children` and all relationship metadata.
- [x] 1.3 Use `total` and returned top-level groups to drive pagination, so children never consume page capacity or cross pages.

## 2. Package history UI

- [x] 2.1 Render returned top-level relationship groups and their addon children with the existing package metrics and status styling.
- [x] 2.2 Initialize groups from `expand_by_default` and add an accessible expand/collapse control for groups with children.
- [x] 2.3 Render `master_missing` as a standalone relationship-exception item and preserve normal shared-request error handling for all other API failures.

## 3. Verification

- [x] 3.1 Verify nested, collapsed, expanded, filtered-group, `master_missing`, and multi-page response fixtures.
- [x] 3.2 Run the H5 production build and inspect the changed files for contract consistency.