docs: "## Sync KOReader Progress - Multiple Books\n\nSynchronizes reading progress for multiple books in a single request.\n\n**Method:** POST\n\n**Endpoint:** /api/sync/koreader/progress\n\n**Authentication:** Bearer token\n\n**Request Body:**\n- `library_id` (string, optional): Library UUID\n- `books` (array): Multiple book progress items\n  - Each item contains: uuid, title, authors, progress, percentage, last_read, chapter, epubcfi\n\n**Response:**\n- `synced` (integer): Number of books successfully synced\n- `failed` (integer): Number of books that failed\n- `results` (array): Per-book sync results\n- `timestamp` (string): Sync timestamp\n\n**Status Codes:**\n- 200: Batch sync completed\n- 207: Multi-status (partial success)\n- 401: Unauthorized\n- 413: Payload too large\n\n**Batch Sync Advantages:**\n- Efficient sync of entire library\n- Single HTTP request for multiple books\n- Faster periodic sync\n- Reduced battery usage vs individual syncs\n- Better for batch processing\n\n**KOReader\
  \ Batch Behavior:**\n- Triggered on device wake from sleep\n- Occurs during \"Sync now\" operation\n- Runs on WiFi connection\n- Limited to 100 books per request\n- Automatic retry on failed books\n\n**Performance:**\n- Small batch (2-10 books): 200-500ms\n- Medium batch (10-50 books): 500ms-2s\n- Large batch (50-100 books): 2-5s\n- Timeout: 30 seconds\n\n**Use Cases:**\n- Device initialization sync\n- Periodic background sync\n- Post-offline catch-up sync\n- Library-wide progress update\n- Before firmware update"
http:
  body:
    json:
      books:
      - authors:
        - Author One
        chapter: 1
        epubcfi: epubcfi(/6/4/2:10)
        last_read: '2026-01-30T19:00:00Z'
        percentage: 0.25
        progress: 0.25
        title: Book One
        uuid: '{{media_item_id}}'
      - authors:
        - Author Two
        chapter: 8
        epubcfi: epubcfi(/6/4/2:50)
        last_read: '2026-01-30T20:00:00Z'
        percentage: 0.75
        progress: 0.75
        title: Book Two
        uuid: '{{media_item_id}}'
      library_id: optional-library-uuid
    type: json
  headers:
  - key: Content-Type
    value: application/json
  method: POST
  url: '{{base_url}}/api/sync/koreader/progress'
  auth:
    type: bearer
    token: '{{koreader_device_token}}'
info:
  name: Sync Progress - Multiple Books
  seq: 2
  type: http