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A guy wrote in his e-ink tablet, and his tablet wrote back. Yes, an actual reply, in the same fading ink style Tom Riddle’s diary uses in Harry Potter. Isn’t that mind-blowing? Certainly, AI is helping the most creative people turn their weird ideas into software.
The person behind it is Maxime Rivest, who hooked his reMarkable tablet up to Fable, one of Anthropic’s newer AI models, and built something that behaves exactly like the cursed diary from the books.
You write a question by hand, your words sink into the page like they’re being absorbed, then new handwriting rises in response, like something on the other side just read what you wrote and decided to answer.
How the diary trick actually works
The reMarkable is an e-ink tablet built for handwriting, which already gives it that paper-like feel. Rivest’s setup takes it further by having the tablet capture your handwritten note, hand it to an AI model, and write the reply back onto the same page in the same fading style.
The result reads less like a chat window and more like the tablet is alive, which is exactly the effect the diary has in the books.
It’s a small build based on Linux, and it is open source. Not a commercial product, but it’s the kind of demo that makes the underlying tech obvious in a way a normal chatbot screenshot never does. Nobody scrolls past a tablet acting like it’s possessed.
Why a tablet feels different from a chatbot
Since the public release of LLM models and the widespread availability of chatbots, talking to ChatGPT or Claude in a browser doesn’t impress us much anymore. Everyone has experienced it already.
However, the true innovation is now watching the ink fade on a physical page and get replaced with a reply feels like something crossed over from fiction, mostly because it borrows a decade of pop culture dread for free.
J.K. Rowling built the diary to be scary specifically because it writes back. Rivest just proved that the trick works in real life too, with the right hardware and access to a much more powerful LLM model behind it.
It also lands at an odd moment for Fable itself. Anthropic briefly pulled access to the model in June over export control rules before restoring it days later, so seeing someone build something this playful with it says the underlying tool is stable enough to build something meaningful with it, not just something locked in a research sandbox.
I don’t think this replaces a notebook, and I doubt Anthropic had “haunted diary” on its roadmap. But I keep coming back to the idea that a piece of paper can now actually answer you, and that’s a strange line to have crossed so quietly.
Would I want one sitting on my desk? Absolutely! 😀
