Mermaid to Unicode box art (grok-mermaid)

**Tool:** [Mermaid to Unicode box art (grok-mermaid)](https://tools.simonwillison.net/grok-mermaid)

While [exploring the codebase](https://simonwillison.net/2026/Jul/15/grok-build/) for the newly open-sourced Grok CLI coding agent I came across [xai-grok-markdown/src/mermaid.rs](https://github.com/xai-org/grok-build/blob/b189869b7755d2b482969acf6c92da3ecfeffd36/crates/codegen/xai-grok-markdown/src/mermaid.rs), a "self-contained terminal renderer for Mermaid diagrams" written in Rust.

I figured it would be fun to try that out in a browser via WebAssembly. Here's the prompt I ran in Claude Code for web (Fable 5), and this is what the resulting tool looks like: