mermaid-diagrams

Files (10)

• LICENSE
• README.md
• SKILL.md
• advanced-features.md · references/
• architecture-diagrams.md · references/
• c4-diagrams.md · references/
• class-diagrams.md · references/
• erd-diagrams.md · references/
• flowcharts.md · references/
• sequence-diagrams.md · references/

SKILL.md (first lines)

# Mermaid Diagramming

Create professional software diagrams using Mermaid's text-based syntax. Mermaid renders diagrams from simple text definitions, making diagrams version-controllable, easy to update, and maintainable alongside code.

## Core Syntax Structure

All Mermaid diagrams follow this pattern:

```mermaid
diagramType
  definition content
```

**Key principles:**
- First line declares diagram type (e.g., `classDiagram`, `sequenceDiagram`, `flowchart`)
- Use `%%` for comments
- Line breaks and indentation improve readability but aren't required
- Unknown words break diagrams; parameters fail silently

## Diagram Type Selection Guide

**Choose the right diagram type:**

1. **Class Diagrams** - Domain modeling, OOP design, entity relationships
   - Domain-driven design documentation
   - Object-oriented class structures
   - Entity relationships and dependencies

2. **Sequence Diagrams** - Temporal interactions, message flows
   - API request/response flows
   - User authentication flows
   - System component interactions
   - Method call sequences

3. **Flowcharts** - Processes, algorithms, decision trees
   - User journeys and workflows
   - Business processes
   - Algorithm logic
   - Deployment pipelines

4. **Entity Relationship Diagrams (ERD)** - Database schemas
   - Table relationships
   - Data modeling
   - Schema design

5. **C4 Diagrams** - Software architecture at multiple levels
   - System Context (systems and users)
   - Container (applications, databases, services)
   - Component (internal structure)
   - Code (class/interface level)

6. **State Diagrams** - State machines, lifecycle states
7. **Git Graphs** - Version control branching strategies
8. **Gantt Charts** - Project timelines, scheduling
9. **Pie/Bar Charts** - Data visualization

## Quick Start Examples

### Class Diagram (Domain Model)
```mermaid
classDiagram
    Title -- Genre
    Title *-- Season
    Title *-- Review
    User --> Review : creates

    class Title {
        +string name
        +int releaseYear
        +play()
    }

    class Genre {
        +string name
        +getTopTitles()
    }
```

### Sequence Diagram (API Flow)
```mermaid
sequenceDiagram
    participant User
    participant API
    participant Database

    User->>API: POST /login
    API->>Database: Query credentials
    Database-->>API: Return user data
    alt Valid credentials
        API-->>User: 200 OK + JWT token
    else Invalid credentials
        API-->>User: 401 Unauthorized
    end
```

### Flowchart (User Journey)
```mermaid
flowchart TD
    Start([User visits site]) --> Auth{Authenticated?}
    Auth -->|No| Login[Show login page]
    Auth -->|Yes| Dashboard[Show dashboard]
    Login --> Creds[Enter credentials]
    Creds --> Validate{Valid?}
    Validate -->|Yes| Dashboard
    Validate -->|No| Error[Show error]
    Error --> Login
```

### ERD (Database Schema)
```mermaid
erDiagram
    USER ||--o{ ORDER : places
    ORDER ||--|{ LINE_ITEM : contains
    PRODUCT ||--o{ LINE_ITEM : includes

    USER {
        int id PK
        string email UK
        string name

From lrstanley/skills, MIT.

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