Claude-skill-registry-data mermaid-syntax

Authoritative reference for Mermaid diagram syntax. Provides diagram types, syntax patterns, examples, and platform integration guidance for generating accurate Mermaid diagrams.

install

source · Clone the upstream repo

git clone https://github.com/majiayu000/claude-skill-registry-data

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/majiayu000/claude-skill-registry-data "$T" && mkdir -p ~/.claude/skills && cp -r "$T/data/mermaid-syntax" ~/.claude/skills/majiayu000-claude-skill-registry-data-mermaid-syntax && rm -rf "$T"

manifest: data/mermaid-syntax/SKILL.md

source content

Mermaid Syntax Reference

Overview

Mermaid is a JavaScript-based diagramming tool that renders diagrams from Markdown-inspired text definitions. Diagrams render as SVG directly in browsers and are natively supported by GitHub, GitLab, Azure DevOps, Obsidian, and Notion.

Key advantages:

Zero setup (browser-based rendering)
Native Markdown integration (diagrams auto-sync with definitions)
Simpler syntax than PlantUML
No external dependencies

Limitations:

Less customization than PlantUML
C4 support is experimental
No MindMap or JSON visualization

Diagram Types Quick Reference

Type	Keyword	Best For
Flowchart	`flowchart` or `graph`	Process flows, decision trees, workflows
Sequence	`sequenceDiagram`	API calls, request/response flows
Class	`classDiagram`	OOP structures, inheritance, relationships
State	`stateDiagram-v2`	State machines, lifecycle states
ER	`erDiagram`	Database schemas, entity relationships
Gantt	`gantt`	Project timelines, schedules
Pie	`pie`	Distribution, proportions
Git Graph	`gitGraph`	Branching strategies, commit history
C4 Context	`C4Context`	System architecture (experimental)
Timeline	`timeline`	Chronological events

Markdown Integration

Mermaid diagrams are embedded in Markdown using fenced code blocks:

```mermaid
flowchart TD
    A[Start] --> B[End]
```

Platform support:

GitHub: Native rendering in README, issues, PRs, wikis
GitLab: Native rendering in Markdown files
Azure DevOps: Native rendering in wikis and repos
Obsidian: Native with core plugin
VS Code: With Markdown Preview Mermaid Support extension

Quick Reference Card

Flowchart

flowchart TD
    A[Box] --> B{Decision}
    B -->|Yes| C[Action]
    B -->|No| D[Other]

Sequence

sequenceDiagram
    A->>B: Request
    B-->>A: Response

Class

classDiagram
    class Name {
        +attribute type
        +method() return
    }
    A <|-- B : inherits

State

stateDiagram-v2
    [*] --> State1
    State1 --> State2 : event
    State2 --> [*]

ER

erDiagram
    ENTITY1 ||--o{ ENTITY2 : relationship
    ENTITY1 {
        type attribute PK
    }

References

For detailed syntax and complete examples, see:

Reference	Content	When to Load
flowchart.md	Node shapes, edge types, subgraphs	Creating flowcharts
sequence.md	Participants, arrows, activation, alt/loop	Creating sequence diagrams
class.md	Classes, visibility, relationships, cardinality	Creating class diagrams
state-er.md	State machines, ER diagrams, relationships	Creating state/ER diagrams
special-diagrams.md	Gantt, Git Graph, C4, styling, gotchas	Creating special diagrams

Test Scenarios

Scenario 1: Creating a flowchart

Query: "Create a Mermaid flowchart for user registration process"

Expected: Skill activates, provides flowchart syntax with decision nodes and subgraphs

Scenario 2: Creating a sequence diagram

Query: "Generate a Mermaid sequence diagram for API authentication"

Expected: Skill activates, provides sequence syntax with participants and alt/loop blocks

Scenario 3: Creating an ER diagram

Query: "Create a Mermaid ER diagram for a blog database"

Expected: Skill activates, directs to state-er.md reference for entity attributes and relationships

Last Updated: 2025-12-28 Mermaid Version: 10.x / 11.x

Version History

v1.1.0 (2025-12-28): Refactored to progressive disclosure - extracted content to references/
v1.0.0 (2025-12-26): Initial release