Penmentor lets Claude, Gemini or GPT annotate handwritten math in xournal++
Penmentor is an open‑source xournal++ plugin that lets users invoke Claude, Gemini or GPT with a single key press to mark up handwritten math. The AI draws coloured pens around mistakes, ticks correct steps, and offers hints instead of full answers. It can also generate a 3Blue1Brown‑style manim animation for selected expressions, letting users drag bounds or change values and watch Riemann sums…
Key points
- Penmentor integrates Claude, Gemini or GPT to mark up handwritten math in xournal++ with coloured hints.
- It can produce interactive 3Blue1Brown‑style manim animations for selected integrals or expressions.
- Installation involves cloning the GitHub repo and binding the script to a key on Linux with X11, rofi, slop, xdotool and PyQt6.
The tool runs on the AI command‑line agent you already have subscribed to, and you choose the model in the Settings menu. Installation is a simple git clone of the GitHub repo (github.com/AbdullahAlhariri/penmentor) followed by binding the provided binary to a keyboard shortcut. It requires Linux with X11, rofi, slop, xdotool and PyQt6. Once set up, the AI feedback stays on the page while you continue writing, and pressing Esc clears the marks.
Show HN: Penmentor – Claude marks up your handwritten math like a teacher
github.com · 17 October 2026Loading the full article…
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