Upgrades the reader's last-read tracking from {chapter} to {chapter, page}.
- ReadingProgressButton: storage is now JSON {chapter, page}; legacy
bare-number values are read back as {chapter, page: 1}. Button label
is unchanged ("继续阅读 · #N title") — the extra precision lives in
the reader's first-fetch offset, not the label.
- PageReader: on mount with saved progress, seed offsetRef to
(page - 1) so the first /api/pages call starts AT the resumed page
instead of the beginning of the chapter. currentPageNum state is
initialized from storage too, so the first persist write is a no-op
that matches the saved value.
- Scroll tracker now also tracks currentPageNum (last page whose top
has crossed above viewport top+80), and persistence writes the
{chapter, page} pair on each change.
Known limitation: earlier pages of the resumed chapter aren't loaded
yet — a follow-up commit adds scroll-up prefetch for those.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
yiekheng
0c6425f0ff