A diagram is data, not a drawing

Short summary

The author tested having an LLM generate a 44-node architecture diagram as raw SVG versus typed JSON processed by a layout engine. SVG output failed on edge routing — a structural limitation of token prediction, not model quality. The solution is to let models emit typed JSON and delegate spatial math to a real layout engine like ELK, enabling validation, deterministic rendering, and scalable server-side deployment without headless browsers.

• •LLMs place boxes well but fail at edge routing in dense graphs — a structural limitation of token prediction
• •Typed JSON output + layout engine (ELK) beats raw SVG: enables validation, diffing, and deterministic re-rendering
• •Glyphic tool renders diagrams server-side in Rust without headless Chromium, deployable as a Node dependency

Generated with AI, which can make mistakes.