LUMEN TUTOR · OPEN SOURCE
Lumen is an AI tutor that teaches by drawing. Ask it a calculus question and it synthesizes structured canvas commands, then strokes the answer onto a live Excalidraw whiteboard: axes, the curve, a sweeping tangent, the shaded area beneath it. This is the earlier, full-stack chapter of Lumen, the FastAPI teaching engine that Lumen Frontier later stubbed out.
Run the FastAPI backend with uvicorn app.main:app --reload, then the Astro whiteboard with npm run dev; it calls GPT-4o through an embedding-similarity cache.