diagram-claude-plugin

diagram-claude-plugin

A Claude Code plugin that generates professional diagrams from natural language. It routes each request to the best-fit Python library, produces a uv run-compatible script, and saves both the script and SVG output for version control.

Installation

Add the plugin to your Claude Code settings (.claude/settings.json):

{
  "extraKnownMarketplaces": [
    "https://github.com/edmondop/diagram-claude-plugin"
  ]
}

Prerequisites

• Python 3.10+
• uv — scripts use uv run with inline dependency metadata
• Graphviz (system binary) — required for graphviz, diagrams, seqdiag, and blockdiag libraries

Install Graphviz:

# macOS
brew install graphviz

# Ubuntu / Debian
sudo apt-get install graphviz

# Fedora
sudo dnf install graphviz

Supported Diagram Types

Diagram type	Primary library	Alternative	When to pick alternative
Flowchart / pipeline	graphviz	schemdraw	No Graphviz installed; simple linear flow
Generic architecture	graphviz	--	--
Cloud/infra architecture	diagrams (mingrammer)	graphviz	Don't need cloud provider icons
ERD	graphviz	--	--
Pyramid / stacked layers	svgwrite	drawsvg	Prefer cleaner API, less precise control needed
Sequence diagram	seqdiag	svgwrite	seqdiag for speed; svgwrite for full control
Network / DAG	networkx + matplotlib	graphviz	graphviz for DOT-style output
Block diagram	blockdiag	schemdraw	schemdraw for flow-style blocks
State machine / FSM	graphviz	--	--

Usage

Use the /diagram slash command or just ask Claude to draw something:

/diagram authentication flow for a web app

Draw me an ERD for an e-commerce system with users, orders, and products

Create a cloud architecture diagram showing an AWS setup with ECS, RDS, and ElastiCache

The plugin will classify the diagram type, suggest a library, generate a script, run it, and open the SVG for review. You can iterate on the output until it looks right.

Development

Install just, then run all checks:

just all

This runs ruff (lint + format), pyrefly (type check), markdownlint, and smoke tests for all scripts.

License

MIT — Copyright (c) 2026 Edmondo Porcu