In an eventually consistent database, if you ask two different replicas the same question at the same time, you may get two different answers.
Linearizability is the idea of making a system appear as if there were only one copy of the data, and all operations on it are atomic.
Reading it for the third time. Understanding every word and none of the ideas.
Ask about whatever you don't understand, the way you'd actually ask. The agent knows the whole book, knows your goal, and explains it at your level, until it clicks.
Every explanation carries its citation. Tap it and verify it in the book, word for word.
This pattern of read-modify-write can cause lost updates. An atomic compare-and-set operation avoids the lost update by only allowing the write if the value has not changed since you last read it.
Cited review
What matters becomes flashcards. They come back to you right before you'd forget. And each one remembers which page it came from — in case you want to reread it.
It's a real card. Try it.
No account. No server. Nobody in between. Everything lives on your device, and you can take it with you anytime.
Private by design. That's BookReader.
And also: highlights and notes, in-book search, bookmarks, pages or scroll, three reading themes, Anki and Markdown export, and it works offline.
The app is free. The agent runs on your own AI key (BYOK): you pay your provider only for what you use — no middleman, no subscription.
EPUB and PDF. The agent reads both equally well: same chat, same citations, same flashcards.
Yes. Read in English and ask in Spanish, or the other way around: the agent understands your question, searches the book and answers in your language, citing the original passage.
Any provider with an OpenAI-compatible API: set the URL, your key and whichever model you want. Without the agent, BookReader is still a complete reader.
In your browser's storage, on your device. They are never uploaded anywhere. You can sync annotations through your own Google Drive and export a full backup anytime.
The agent answers from passages of the book and cites every claim. The citation is your verify button: one tap and you're on the page. If the book doesn't cover something, it says so instead of filling in.
Reading, highlighting and reviewing cards: yes, it's an installable PWA. The agent needs a connection to talk to your AI provider.