An AI tutor that reads handwriting, not just typing

Reading handwritten prose is a solved-enough problem. Reading handwritten maths and physics is not, because the meaning is in the layout as much as the characters — a number sitting above a line is a numerator, the same number half a size smaller and raised is an index, and a bracket three lines tall changes what all of it applies to.

Add the things a real page has and a clean transcription model has not seen: a crossing-out, an arrow to the margin, a substitution written above a term, a step abandoned halfway.

Plumi reads that structure rather than flattening the page into a line of text, which is what lets it point at a specific step rather than commenting on the page as a whole.

It matters because the step is where the teaching is. “This is wrong” helps nobody; “the substitution on line three is fine, but you have not changed the limits” is a lesson.

• Fractions, indices, integrals, vectors and bracket scope read as structure.
• Crossings-out and abandoned steps treated as what they are, not as errors.
• Your own handwriting stays on the page — Plumi writes beside it, never over it.

There is a decent argument that handwriting is the point rather than an obstacle to be automated away. Working something out by hand is slower than typing, and the slowness is doing something: it is where you notice that a step does not follow.

So Plumi is not trying to get you to stop writing. It is trying to be useful while you do — which is why the tutoring appears in the margin, in handwriting, and why you keep the pen throughout.