sync_flutter

An open-source system that aligns an EPUB with a matching audiobook and highlights text word by word during playback.

Core Principles Contracts first: keep API, sync JSON, and reader data stable. Deterministic rendering: the reader must highlight the same token model the backend aligned. Async by default: alignment is a long-running job, not a request-response action. Offline matters: completed projects must work without network access. Mismatch tolerance matters more than perfect happy-path demos.