uml-modeling

# UML Modeling Skill

## When to Use This Skill

Use this skill when:

- **Uml Modeling tasks** - Working on uml diagram generation including class, sequence, activity, use case, and state diagrams
- **Planning or design** - Need guidance on Uml Modeling approaches
- **Best practices** - Want to follow established patterns and standards

## Overview

Create UML diagrams using PlantUML and Mermaid notation for software design documentation.

## MANDATORY: Documentation-First Approach

Before creating UML diagrams:

1. **Invoke `docs-management` skill** for UML standards guidance
2. **Verify diagram syntax** using appropriate notation (PlantUML/Mermaid)
3. **Base all guidance on UML 2.5 specification**

## UML Diagram Types

### Structural Diagrams

| Diagram | Purpose | When to Use |
|---------|---------|-------------|
| Class | Show classes, attributes, methods, relationships | Domain modeling, design |
| Component | Show components and dependencies | Architecture documentation |
| Deployment | Show physical deployment | Infrastructure planning |
| Object | Show object instances | Specific scenarios |
| Package | Show namespaces/modules | Code organization |

### Behavioral Diagrams

| Diagram | Purpose | When to Use |
|---------|---------|-------------|
| Use Case | Show actor-system interactions | Requirements |
| Sequence | Show message flow over time | API design, protocols |
| Activity | Show workflows and processes | Business processes |
| State Machine | Show state transitions | Lifecycle modeling |
| Communication | Show object interactions | Design patterns |

## Class Diagram

### PlantUML Syntax

```plantuml
@startuml
skinparam classAttributeIconSize 0

abstract class Entity {
  +Id: Guid
  +CreatedAt: DateTimeOffset
  +UpdatedAt: DateTimeOffset
}

class Order extends Entity {
  -_lineItems: List<LineItem>
  +CustomerId: Guid
  +Status: OrderStatus
  +Total: Money
  --
  +AddItem(product: Product, quantity: int): Result<LineItem>
  +RemoveItem(lineItemId: