Diagram Design

Editorial diagrams your designer won't hate.

New in 2.0 — the Loop: flywheels with a shared-memory hub. The dashed lines are the write-backs.

New in 2.3: semantic system patterns and optional accessible motion, while static output stays the default.

New in 2.5.10: ten more layout grammars — Sankey, fishbone, Wardley map, kanban, user journey, deployment, dependency graph, UML class, story map, and database schema.

39 editorial diagram types for Claude Code, Codex, Factory Droid, Pi, and Agent Skills-compatible hosts. Self-contained HTML + SVG. No shadows. No Mermaid slop. Semantic patterns describe behavior separately from layout, so a queue, policy trace, or trust boundary can use the nearest existing type without expanding the type count. Static HTML remains the default; optional motion is available for ordered explanations. The skill also redraws draw.io, Mermaid, or Excalidraw sources at a chosen format, size, and detail level.

No Figma. No generic rounded boxes. No 30-minute color-picking sessions.

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Why I built it

I write at littlemight.com (and run BestSelf.co on the side). Every time I needed a diagram — an architecture sketch, a flowchart, a pyramid of what matters most — I'd ask Claude and get back a generic rounded-box thing that looked nothing like the rest of the site. I'd either fight with Figma for 30 minutes or just skip the diagram.

So I built a Claude Code skill for it. Thirty-nine visual types, editorial quality, matches your brand in 60 seconds by reading your website.

The highest-quality move is usually deletion. Every node earns its place. The accent color is reserved for the 1–2 things the reader should look at first. Target density: 4/10.

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What it makes

All 39 visual types ship in three static variants: minimal light, minimal dark, and full-editorial. Open any of them directly in a browser. There is no build step, JavaScript, or external image dependency.

Architecture Components + connections	IT current-state Legacy landscape + modernization	Flowchart Decision logic
Sequence Messages over time	State machine States + transitions	ER / data model Entities + fields
Timeline Events on an axis	Swimlane Cross-functional flow	Quadrant Two-axis positioning
Radar / spider Multi-axis comparison	Loop / flywheel Reinforcing cycle + shared hub	Nested Hierarchy by containment
Tree Parent → children	Org chart Ownership + routing	Layer stack Stacked abstractions
Venn Set overlap	Pyramid / funnel Ranked hierarchy or drop-off	Bar chart Categorical comparison
Treemap Part-of-whole by area	Line chart Trends over time	Gantt Tasks + phases on a timeline
Scatter plot Distribution + correlation	High-Level End-to-end stack on a cluster	Process Multi-actor sequential workflow
Medallion Multi-tier data storage	Data flow Role-scoped pipeline steps	DP integration Sources → core → consumers
DP security matrix Per-role access permissions	Sankey Quantities that split + merge	Fishbone Grouped causes → one effect
Wardley map Value chain × evolution	Kanban Work in progress by state	User journey Stages, actions + sentiment
Deployment Zones, hosts + artifacts	Dependency graph Fan-in, ranks + cycles	UML class Classes, operations + typed relations
Story map Backbone × release slices	Database schema Physical tables + column FKs	Polar chart Cyclic magnitude · linear radius
Waterfall Running total + signed bridges

The v2.5.10 release added the final ten types above. Compare their light, dark, and full-editorial variants in the 30-variant contact sheet.

Browse the live gallery: cathrynlavery.github.io/diagram-design — or open skills/diagram-design/assets/index.html locally to flip through all 39 diagrams with light / dark / full-editorial tabs.

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Install

Claude Code:

/plugin marketplace add cathrynlavery/diagram-design
/plugin install diagram-design@diagram-design

Then enable updates once: run /plugin, open Marketplaces, select diagram-design, and choose Enable auto-update. Claude Code disables auto-update by default for third-party marketplaces; after this toggle, it refreshes the marketplace and installed plugin in the background after startup. Run /reload-plugins when prompted, or let the next session load the update.

Codex:

codex plugin marketplace add cathrynlavery/diagram-design
codex plugin add diagram-design@diagram-design

Codex refreshes configured Git marketplaces at startup. To fetch immediately, run codex plugin marketplace upgrade diagram-design and start a new session.

GitHub Copilot:

copilot plugin marketplace add cathrynlavery/diagram-design
copilot plugin install diagram-design@diagram-design

Copilot installs the shared Diagram Design skill plus its doctor, export, import, and profile capabilities from the existing repository marketplace. Confirm discovery with copilot skill list (or /skills in an interactive session), then ask for a diagram in natural language. To fetch a merged update, run copilot plugin marketplace update diagram-design, then copilot plugin update diagram-design@diagram-design.

Factory Droid:

droid plugin marketplace add https://github.com/cathrynlavery/diagram-design
droid plugin install diagram-design@diagram-design --scope user

Droid tracks Git plugins by commit rather than the manifest's display version. To fetch a merged update, run droid plugin marketplace update diagram-design, then droid plugin update diagram-design@diagram-design --scope user, and start a new session.

Claude Cowork (organization marketplace): Organization GitHub marketplaces currently require a private or internal repository, so first mirror this public repository into one owned by your organization. In Organization settings → Plugins, choose Add plugin → GitHub, connect that mirror, and enable Sync automatically from the marketplace menu. Automatic sync runs when a pull request containing a plugin version bump is merged to the mirror's default branch; direct pushes do not trigger the webhook. Install Diagram Design from the resulting organization marketplace.

Pi:

pi install https://github.com/cathrynlavery/diagram-design

Run /reload in an open Pi session. Pi makes the skill available for matching diagram requests; use /skill:diagram-design to invoke it explicitly. Pi also loads the /export-diagram, /import-mermaid, /import-excalidraw, /profile, and /doctor prompt templates. The unpinned Git install is intentional: Pi has no automatic package refresh, so run pi update --extensions to pull merged updates.

Kiro: Import the Agent Skill from the repository subdirectory URL:

https://github.com/cathrynlavery/diagram-design/tree/main/skills/diagram-design

Kiro copies imported skills into .kiro/skills/ for a workspace or ~/.kiro/skills/ globally, so re-import the URL to pick up updates. Custom agents that declare resources should include skill://diagram-design//SKILL.md.

OpenCode: Copy or symlink skills/diagram-design/ to .opencode/skills/diagram-design in a project or ~/.config/opencode/skills/diagram-design globally. OpenCode has no Diagram Design marketplace package; copied installs update only when you replace the directory from a newer checkout.

One-time migration:** an existing standalone npx skills add copy will not start following the Codex marketplace automatically. Remove that standalone copy, then use the Codex marketplace commands above. Likewise, uninstall a personal Cowork copy and reinstall Diagram Design from your organization's marketplace. Future marketplace version bumps then flow through each client's native update path.

Editable install

Managed installs are convenient, but changes to references/style-guide.md may be replaced by package updates. Saved profiles in ~/.diagram-design/profiles/ survive updates, and projects with a .diagram-design marker are unaffected. Clone the repo and install the local path if you plan to customize the working style guide directly:

git clone [email protected]:cathrynlavery/diagram-design.git ~/code/diagram-design
Pi: register the checkout as a local package
pi install ~/code/diagram-design
Claude Code: symlink the inner skill
ln -s ~/code/diagram-design/skills/diagram-design ~/.claude/skills/diagram-design
Other Agent Skills hosts: create only the roots you use
mkdir -p ~/.agents/skills ~/.cursor/skills ~/.cline/skills ~/.kiro/skills ~/.config/opencode/skills ~/.copilot/skills
ln -s ~/code/diagram-design/skills/diagram-design ~/.agents/skills/diagram-design
ln -s ~/code/diagram-design/skills/diagram-design ~/.cursor/skills/diagram-design
ln -s ~/code/diagram-design/skills/diagram-design ~/.cline/skills/diagram-design
ln -s ~/code/diagram-design/skills/diagram-design ~/.kiro/skills/diagram-design
ln -s ~/code/diagram-design/skills/diagram-design ~/.config/opencode/skills/diagram-design
ln -s ~/code/diagram-design/skills/diagram-design ~/.copilot/skills/diagram-design

The shared skill lives at skills/diagram-design/. Pi discovers it through the repo's standard skills/ package directory; Claude Code, GitHub Copilot, Codex, Factory Droid, and other Agent Skills-compatible tools use the same files.

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Onboarding — make it look like your brand

The whole point: ship editorial-quality diagrams in your colors and typography, not a generic template.

Out of the box, diagrams render in a clean jet-black + atomic-tangerine palette (white-smoke paper, jet-black ink, atomic-tangerine accent, blue-slate muted, silver hairlines). Good enough to screenshot straight away. But 60 seconds of onboarding is better — the skill will pull your brand from your website and apply it across every diagram.

The flow

You:     "onboard diagram-design to https://yoursite.com"
Agent:   → fetches the homepage
         → extracts the dominant palette + font stack
         → maps detected values to semantic roles:
             paper, ink, muted, accent, link
         → shows a proposed diff
         → writes your tokens to references/style-guide.md
You:     "yes, apply it"

Every new diagram now uses your colors. Your website's paper color becomes the diagram background. Your CTA color becomes the focal accent. Your body font stack becomes the node label family.

Brand matching also emits a fidelity receipt: sampled URLs, exact color roles, font families and weights, font source URLs, and any fallback. Public site fonts are used directly and verified after rendering rather than silently replaced with generic system fonts.

What gets extracted

| Detected from your site | Becomes | |---|---| | ` background | paper` token | | Primary text color | ink token | | Secondary / caption text | muted token | | Cards or containers | paper-2 token | | Most-used brand color (CTA, link, heading) | accent token | |

font family | title font | | ` font family | node-name` font | | /

 font | sublabel font |

Contrast checks happen automatically
Before writing tokens, the skill verifies WCAG AA contrast on ink over paper. If your site has a color that fails contrast at diagram sizes (9–12px), it proposes an adjusted value and explains why.
Accessible by default
Every diagram template gives the inline SVG an accessible name and description: role="img", a resolving aria-labelledby, and first-child ` / ` slots. IDs are prefixed per diagram and variant, so multiple SVG exports can be safely inlined on one page without duplicate accessible-name IDs. Decorative specimen icons are hidden from assistive technology instead.
Manual override
Prefer to set tokens by hand? Open skills/diagram-design/references/style-guide.md and edit the table. Everything downstream reads from there — all 39 diagrams, the annotation primitive, and the gallery all inherit semantic role names (accent, not #eb6c36).
First-run gate
The skill won't silently ship default-skinned diagrams into a branded project. On first use in a new project, it checks if style-guide.md has been customized. If not, it pauses and asks:
"This is your first diagram in this project. The style guide is still at the default. Want to run onboarding, paste tokens manually, or proceed with default?"
See skills/diagram-design/references/onboarding.md for the full spec.
Working with multiple clients
Onboard a brand once, save the result as a named profile, then add a .diagram-design marker containing profile:  to each client project. Marker projects read ~/.diagram-design/profiles/.md directly, so parallel workspaces can use different brands without overwriting a shared installed style-guide.md.
The profile library is shared across Claude Code, Codex, Factory Droid, and Pi. Use /diagram-design:profile in Claude Code, /profile in Factory Droid or Pi, or ask in natural language in any host. See profiles.md for the storage, marker, and recovery contract.
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Quickstart
# From a cloned checkout, open the gallery to see all 39 diagrams
open skills/diagram-design/assets/index.html       # macOS
xdg-open skills/diagram-design/assets/index.html  # Linux
In Claude Code, Codex, Factory Droid, or Pi, ask:
"Make me an architecture diagram of my app: frontend, backend, database, Redis cache."
"I need a quadrant showing Q2 projects by impact vs effort."
"Give me a sequence of a bearer call with token refresh on 401."
(branching refresh uses the ALT combined-fragment grammar in type-sequence.md;
see skills/diagram-design/assets/example-sequence-oauth.html — not a full authorize-code handshake)

Operator recipes for editable installs, first diagrams, brand setup, import, export, validation, Windows junctions, and reusable prompts live in docs/cookbook.md.
Your agent will pick the right type, build the HTML, and save it. You can also start from a template directly:
cp skills/diagram-design/assets/template.html my-diagram.html        # minimal light
cp skills/diagram-design/assets/template-full.html my-diagram.html   # editorial with summary cards
cp skills/diagram-design/assets/template-motion.html my-diagram.html # optional accessible motion

Semantic patterns and optional motion
When behavior matters, the skill chooses a semantic pattern first and a visual type second. The eight routed patterns cover fan-in queues and bottlenecks, repeated stage slots, unstructured-input transformation, paired policy traces, secure paved roads, governance catalogs, compensating security layers, and traceable block decomposition. Each pattern defines its triggers, primitives, budget, anti-patterns, static fallback, and nearest visual type in semantic-patterns.md.
Motion is optional and does not create another visual type. animation.md defines none, reveal, step, and loop modes with a complete static first frame, deterministic timing, and controls when interaction is available. Reduced-motion output shows the complete static frame and hides/disables playback controls. Motion HTML uses the exact reviewed controller from template-motion.html; arbitrary or modified inline scripts, remote assets, CSS imports, and executable HTML attributes are rejected. The default is none: ordinary output remains static and script-free. example-policy-trace-animated.html is the self-contained interactive example.
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Import from draw.io, Mermaid, or Excalidraw
Already have diagrams in draw.io / diagrams.net, Mermaid, or Excalidraw? Point the skill at the source and it redraws them — same content, this design system, at whatever the destination needs.

A 12-node draw.io file redrawn at balanced detail for a blog post. The source's six pastel fills became one accent; its hand-dragged coordinates became a 4px grid.
```
/diagram-design:import-drawio