use-case-authoring

# Use Case Authoring Skill

Use Case 2.0 methodology for capturing functional requirements and documenting actor-system interactions.

## MANDATORY: Documentation-First Approach

Before authoring use cases:

1. **Invoke `docs-management` skill** for requirements patterns
2. **Verify Use Case 2.0 methodology** via MCP servers
3. **Base all guidance on Ivar Jacobson's Use Case 2.0**

## Use Case 2.0 Overview

Use Case 2.0 is a scalable, agile practice for capturing requirements:

| Aspect | Description |
|--------|-------------|
| Lightweight | Start minimal, elaborate as needed |
| Scalable | Works for small and large systems |
| Agile-Friendly | Supports iterative development |
| Traceable | Links to tests and implementation |

## Use Case Structure

### Use Case Specification Template

```markdown
# Use Case: Submit Order

**ID:** UC-ORD-001
**Version:** 1.2
**Author:** System Analyst

## Brief Description
Customer submits a draft order for processing, triggering inventory reservation and payment processing.

## Actors
| Actor | Type | Description |
|-------|------|-------------|
| Customer | Primary | Person placing the order |
| Payment Gateway | Supporting | External payment processor |
| Inventory System | Supporting | Manages product stock |

## Preconditions
1. Customer is authenticated
2. Order exists in Draft status
3. Order contains at least one item
4. Customer has valid payment method on file

## Postconditions
### Success Postconditions
1. Order status changed to Submitted
2. Inventory reserved for all items
3. Payment authorization obtained
4. Confirmation notification sent to customer

### Failure Postconditions
1. Order remains in Draft status
2. No inventory changes made
3. Customer notified of failure reason

## Basic Flow (Happy Path)

| Step | Actor | System |
|------|-------|--------|
| 1 | Customer selects "Submit Order" | |
| 2 | | System validates order contents |
| 3 | | System checks inventory availability |
| 4 | | System reserves inventor