Sukey And The Mermaid

So You Want To Work With Sukey And The Mermaid

I came across this a while back while scrolling through some code repositories. Sukey And The Mermaid is a small open-source utility people seem to use for generating procedural mermaid diagrams from structured data files. Nothing fancy. It reads JSON or YAML, applies a template, and spits out diagram markup you can render in any mermaid-compatible viewer. The GitHub repo is at github.com/tidal-scribe/sukey-and-the-mermaid. The latest release is version 0.4.2. It's written in Rust, which means the build times are reasonable and the binary is tiny, around 12 megabytes when compiled for Linux x64.

Installing Sukey And The Mermaid

If you're on macOS or Linux, the easiest route is using cargo: cargo install sukey-mermaid. On Windows, grab the prebuilt binary from the releases page. Don't try to compile from source there unless you enjoy spending two hours fixing missing OpenSSL dependencies. There's also an npm wrapper package called sukey-mermaid-cli if you'd rather stay in JavaScript land. I don't recommend it. The Node wrapper adds about 400 milliseconds of startup overhead and pulls in a handful of unnecessary dependencies. Use the binary directly.

How It Actually Works

Here's the basic flow. You write a schema file describing your entities and their relationships, run the tool against it, and it outputs mermaid-compatible graph syntax. The output goes to stdout by default, so you pipe it into a file or feed it straight to a renderer. A typical workflow looks like this: Create a file called diagram.yaml:

entities: - name: User type: actor - name: Database type: storage relationships: - from: User to: Database label: queries Then run: sukey-mermaid render diagram.yaml --output output.mmd That's it. You now have a mermaid diagram file you can open in any supported viewer. The whole process takes about three seconds on my machine from start to output.

A Few Things Nobody Talks About

The first thing is that the layout engine is basically unconfigured. Sukey And The Mermaid hands off to mermaid's built-in dagre layout. If you have more than roughly twenty entities, the diagram gets messy fast. I've seen people throw fifty-node schemas at it and then complain the output is unreadable. It's not a bug. Dagre isn't designed for large graphs. If you need bigger diagrams, look into Mermaid's ELK layout plugin instead. Sukey And The Mermaid doesn't support plugging that in yet. The second thing is styling. The tool has a --theme flag with three options: default, dark, and forest. That's it. If you need custom colors, border styles, or conditional formatting based on entity type, you're stuck doing post-processing with sed or writing a small script. I wrote a Python helper that reads the output .mmd file and applies color rules based on entity labels. It took me about forty minutes to build and saves me maybe five minutes per render. The math doesn't work out unless you're generating these daily. One edge case I ran into: the YAML parser chokes on unquoted values that contain colons. If your entity name or relationship label has something like "Status: Active", the parser tries to interpret the colon as a key-value separator and throws a confusing error. The workaround is to quote any value containing a colon. Simple, but not obvious if you're just skimming the documentation.

Another gotcha: version 0.4.0 introduced a breaking change in how nested entities are handled. The previous version allowed embedding one entity definition inside another. 0.4.0 removed that. If you're upgrading from an older release, your existing schema files will silently produce incomplete output instead of erroring out. Check your generated diagrams after any upgrade. I lost about an hour last month tracing a bug that turned out to be a migration issue.

When Not To Use It

Don't use Sukey And The Mermaid if you need real-time collaborative editing, if your diagrams need to update live as your data changes, or if you require publication-quality visual output. It's a batch renderer, not a drawing tool. For anything interactive, something like Draw.io or Lucidchart does more with less friction. It's useful if you're generating diagrams as part of an automated pipeline — CI/CD reports, documentation generation, or embedding architecture visuals in markdown-based wikis. In those contexts, the speed and scriptability matter more than polish. The project is maintained by a small team and updates are infrequent. Roadmap items get discussed in issues but rarely land in releases. If that matters to you, fork it and maintain your own version. That's what most serious users end up doing anyway.