Progress Sync

Each device writes its progress to its own sync file in iCloud Drive, so devices never overwrite each other. Progress is periodically bundled and saved, and written immediately when the app moves to the background.

When opening a book, the app checks if another device has newer progress. If so, you can switch to the newer progress or continue at your local position.

The transcription index is also shared via iCloud. A second device doesn't need to re-transcribe the audiobook — the completed index is automatically adopted.