---
name: use-case-diagram
description: >
  Creates or updates PlantUML use case diagrams defining actors, use cases,
  and their relationships from requirements. Use when the user asks to
  "create a use case diagram", "draw a UML diagram", "map actors to use cases",
  "generate a .puml file", or mentions PlantUML, use case overview, actor
  diagram, or system use cases.
---

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Part of the AI Unified Process — https://unifiedprocess.ai
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# Use Case Diagram

## Instructions

Create or update the PlantUML use case diagram at `docs/use_cases.puml` based on `docs/requirements.md`.

## DO NOT

- Create diagrams without reading the requirements first
- Use non-standard PlantUML syntax
- Include implementation details in use case names

## Template

```plantuml
@startuml Use Cases Overview
left to right direction

actor "User" as user
actor "Administrator" as admin

rectangle "System Name" {
    usecase "UC-001\nDescription" as UC001
    usecase "UC-002\nDescription" as UC002
    usecase "UC-003\nDescription" as UC003
}

admin --> UC001
user --> UC002
user --> UC003

@enduml
```

## Conventions

- Each use case has a unique id and a description
- Use Case ID: UC-{3-digit} (UC-001, UC-002, ...)
- Each use case should trace to at least one functional requirement
- Add notes sparingly, only where relationships need clarification

## Workflow

1. Read the requirements at `docs/requirements.md`
2. Read existing diagram at `docs/use_cases.puml` (if exists)
3. Identify actors and use cases from requirements
4. Create/update the PlantUML use case diagram
5. Validate the diagram:
    - Each use case traces to at least one functional requirement in `docs/requirements.md`
    - All actors are connected to at least one use case
    - Use case IDs follow the UC-{3-digit} convention
    - PlantUML syntax is valid (no missing `@enduml`, proper arrow syntax)