# Data Model: Tag Browser

No schema changes are required for this feature. All data needed to power the tag browser already exists.

## Derived Entity: Tag with Count

The tag browser displays a **read-only, derived view** of existing data:

| Field | Source | Notes |
|-------|--------|-------|
| `name` | `tags.name` | Lowercase, normalised string |
| `image_count` | `COUNT(image_tags.image_id) WHERE image_tags.tag_id = tags.id` | Computed at query time |

This is exactly the shape already returned by `GET /api/v1/tags` as `{"id", "name", "image_count"}`.

## What Changes

The query in `TagRepository.list_tags()` gains two optional behaviours:

1. **Sort by count descending** — adds `ORDER BY image_count DESC, name ASC` (count-desc primary, alphabetical secondary) instead of the current `ORDER BY name ASC`.
2. **Exclude zero-count tags** — adds `HAVING image_count > 0` (or equivalent `WHERE` on the subquery) when `min_count=1` is requested.

No new tables, columns, indexes, or migrations are needed.