diagram-design: editorial diagrams from agent skills

TL;DR: diagram-design is an agent skill that gives Claude Code, Codex, GitHub Copilot, Factory Droid, and Pi a 42-type diagram vocabulary rendered as self-contained HTML and SVG. At 44,070 stars it is the most-starred repository in today’s trending batch by a wide margin, and its description openly positions itself against Mermaid.

What the project is

Read the description carefully, because it is doing more than listing features:

Editorial diagram design for Claude Code, Codex, GitHub Copilot, Factory Droid, and Pi. 42 diagram types. Self-contained HTML + SVG. No shadows. No Mermaid slop.

That last sentence is a design position rather than a bug report. Mermaid is the default pick for diagrams-as-code, and this project names it in order to reject it.

The topic list backs the framing. All five entries, agent-skills, claude-code, codex, data-visualization, and diagrams, describe delivery and output. None of them describe analysis, instrumentation, or data pipelines.

What self-contained actually buys you

This is the load-bearing technical claim in the description, and the difference is real.

A Mermaid block is rendered at view time. What you write in the file is a code fence, and it only becomes a picture when a renderer, usually a JavaScript one, runs in a browser. Self-contained HTML plus SVG means the file opens on its own:

<!doctype html>
<meta charset="utf-8">
<style>/* layout rules travel with the file */</style>
<svg viewBox="0 0 800 400"><!-- the diagram itself --></svg>

No CDN, no runtime, no network call. That matters for slides you present from a laptop with no wifi, for diagrams pasted into an email thread, and for anything that has to still render in five years.

The numbers

Field	Value
Stars	44,070
Forks	2,842
Open issues	88
Language	HTML
License	MIT
Topics	agent-skills, claude-code, codex, data-visualization, diagrams
Created	2026-04-16
Last push	2026-10-06
Owner type	User

Two of those numbers read better next to another repository from the same day.

DeepGEMM, also published today, has 1,373 forks against 8,725 stars, roughly 16 percent. This one has 2,842 against 44,070, closer to 6 percent. Same platform, same trending page, very different fork behavior. A kernel library gets used and vendored. A style guide gets read, bookmarked, and pointed at. The 88 open issues against 44,070 stars fits a repository that is mostly content rather than code.

How to look at it

git clone https://github.com/cathrynlavery/diagram-design.git
cd diagram-design

There is a hosted documentation site, which is not the norm for an agent skill:

https://cathrynlavery.github.io/diagram-design/

And to confirm the metadata without trusting this post:

curl -s https://api.github.com/repos/cathrynlavery/diagram-design \
  | jq '{stars: .stargazers_count, topics, license: .license.spdx_id, homepage}'

What I could not verify

• I did not read the README, so I cannot tell you which 42 diagram types are included, or how the skill installs into each of those five clients.
• “No shadows” and “No Mermaid slop” state an aesthetic intent. They do not tell you whether the constraint is mechanically enforced or just modeled in examples.
• The owner type is User, not Organization. One person is holding 44,070 stars of attention, which is worth naming as a risk.

When it fits

You are working inside one of those agent clients, you need architecture or flow diagrams somewhere a Mermaid block will not render, and you care that the output looks deliberate rather than generated.

When it does not fit

If your diagrams live in a README or docs site where Mermaid already works, swapping a working pipeline for 42 hand-tuned styles is churn you do not need.

Also read “editorial” as a constraint, not a freebie. If you are bound to a corporate template or a house color system, an opinionated style guide is going to fight you for every diagram.

Source and Accuracy Notes

• Project page: https://github.com/cathrynlavery/diagram-design
• Documentation site: https://cathrynlavery.github.io/diagram-design/
• Source repository: cathrynlavery/diagram-design (verified via GitHub API html_url)
• License: MIT (verified via GitHub API license.spdx_id)
• Stars at time of writing: 44,070