# Spec Delta

## Purpose

The product brand registry: a bilingual, admin-managed list of manufacturers that products reference, shoppers filter listings by, and the storefront shows on a product.

## ADDED Requirements

### Requirement: Public brand list
`GET /api/brands` SHALL return the brands without authentication, ordered by their stored position, each with an id, slug and bilingual name. Products SHALL carry a nullable `brand_id` referring to that list, and `GET /api/products` SHALL accept a `brand_id` filter that composes with the existing category, shop and keyword filters.

#### Scenario: filter a listing by brand
- **WHEN** a shopper filters the catalog by a brand
- **THEN** only that brand's published products are returned, and the filter combines with a category filter rather than replacing it

#### Scenario: a product without a brand
- **WHEN** a product has no brand assigned
- **THEN** it is still listed and its `brand_id` is null rather than pointing at an invented brand

### Requirement: Brand management
A platform admin SHALL replace the brand list with `PUT /api/admin/brands`, which validates each entry, applies as one transaction and reindexes positions from the submitted order; the write SHALL require the `platform_admin` role. Each entry SHALL carry a slug and non-empty `en` and `zh` names, and a rejected list SHALL leave the stored brands untouched.

#### Scenario: replace round-trips
- **WHEN** an admin replaces the brands and then reads them publicly
- **THEN** the public list matches, in the submitted order

#### Scenario: incomplete bilingual name is refused
- **WHEN** an admin submits a brand with only `en` text
- **THEN** the request fails and the stored brands are unchanged