Grok Open-Sources Mermaid Terminal Renderer, Ported to WebAssembly

Simon Willison discovered xai-grok-markdown/src/mermaid.rs in Grok CLI's open-source code, a self-contained terminal Mermaid renderer written in Rust. He ported it to the browser via WebAssembly, running it in Claude Code for Web (Fable 5) to create an online tool. The tool auto-renders Mermaid syntax into Unicode box-drawing flowcharts, with controls for max width, copy as text, and copy link. An example shows an authentication flow from "Request received" to "Authenticated?" and "Rate limit OK?" to "200 OK", supporting arrow types (solid, dashed, bold) and node shapes (diamond, rectangle, rounded rectangle). For developers needing quick Mermaid diagram viewing in terminal or web, this Wasm version eliminates local Rust or Grok CLI installation, usable directly in browser—ideal for docs or CI output.