# Resolve Book

Map a book's file SHA-256 to its Bookhoard UUID without touching progress
state. Used by devices to link a freshly downloaded book before their first
pull, so the device's first-page position is never pushed (which would
conflict with server-side progress for books already mid-read).

**Endpoint**: `GET /api/sync/koreader/resolve`
**Auth**: Required (Device authentication)

## Query Parameters

| Parameter | Type   | Required | Description                          |
| --------- | ------ | -------- | ------------------------------------ |
| sha256    | string | Yes      | File content hash (64 hex characters) |

Resolution is format-aware: the hash is checked against both
`media_items.file_sha256` and `media_item_formats.file_sha256`, so a
converted file (KEPUB/PDF) matches its media item too.

## Device Authentication

This endpoint requires device authentication (not user JWT). Devices
authenticate using their device credentials.

### Example Request

```http
GET /api/sync/koreader/resolve?sha256=e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
Authorization: Bearer {device_token}
```

## Response (200 OK)

```json
{
  "book_uuid": "550e8400-e29b-41d4-a716-446655440000",
  "sha256": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
  "title": "Book Title",
  "author": "Author Name"
}
```

## Error Responses

| Code | Description                                  |
| ---- | -------------------------------------------- |
| 400  | Missing or malformed `sha256` parameter      |
| 401  | Device authentication failed                 |
| 404  | No book in the library matches the given hash |