Show HN: Penmentor – Claude marks up your handwritten math like a teacher

Category: devtools

Tags: math-education, handwriting-recognition, ai-agent, manim, x11, pen-tablet

Score: 6.8/10 (Innovation: 7, Technical: 7, Documentation: 7, Utility: 6)

Penmentor is a Linux X11 tool that captures handwritten math from a pen tablet (xournal++) and sends it to a CLI AI agent (Claude Code, Codex, or Antigravity) to get teacher-style markup, hints, and even manim animations. It combines screen capture, subprocess orchestration, and GUI overlay to provide an interactive learning experience directly on the user's work.

Target audience: students and educators using pen tablets for math, particularly on Linux

Repository: https://github.com/AbdullahAlhariri/penmentor · Python · MIT · 84 stars

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