openup-create-use-case

# Create Use Case

This skill creates a use case specification from the OpenUP template.

## When to Use

Use this skill when:
- Need to document user interactions with the system
- In Inception or Elaboration phase defining requirements
- Capturing functional requirements from user perspective
- Need to specify preconditions, flows, and postconditions
- Creating test scenarios from requirements

## When NOT to Use

Do NOT use this skill when:
- Need non-functional requirements (use architecture notebook)
- Looking for technical specifications (use design documents)
- Documenting internal system behavior (use technical design)
- Use case already exists (update existing file)

## Success Criteria

After using this skill, verify:
- [ ] Use case file exists in `docs/use-cases/`
- [ ] Use case name and primary actor are defined
- [ ] Basic flow is documented
- [ ] Alternative flows are identified
- [ ] Pre/postconditions are specified

## Process

### Load Project Config (context + rules — do this first)

Before drafting, layer in project-owned context and rules so the artifact reflects
facts and standards the framework can't infer. Full mechanism + precedence:
`docs-eng-process/project-config.md`.

1. If `docs/project-config.yaml` exists, read it. If it is **absent, skip this
   step** — framework defaults apply unchanged.
2. Inject `context:` into your working prompt wrapped in
   `<project-context>…</project-context>`, and `rules.<TYPE>` (if present) wrapped
   in `<project-rules>…</project-rules>`. For this skill `<TYPE>` is **`use-case`**.
3. Project rules are **additive** to the framework rubric — precedence is
   **framework rubric → project rules → task-spec safeguards**. A project rule may
   add a criterion but may **not** waive a framework rubric criterion or a safeguard.
4. Before marking this artifact complete, confirm every injected `<project-rules>`
   item is satisfied alongside the framework rubric.

### 1. Create Use Cases Directory

Ensure `docs/use-cases/` directory exists.

### 2. Generate Filename

Create filename from use case name: `docs/use-cases/<use-case-name>.md`

### 3. Copy Template

Copy `docs-eng-process/templates/use-case-specification.md` to the new file.

### 4. Fill in Use Case

Update the use case specification with:
- **Use case name**: `$ARGUMENTS[use_case_name]`
- **Primary actor**: `$ARGUMENTS[primary_actor]`
- **Description**: `$ARGUMENTS[description]`
- **Preconditions**: What must be true before starting
- **Basic flow**: Step-by-step main interaction
- **Alternative flows**: Alternative paths and edge cases
- **Postconditions**: What is true after completion

### 5. Validate Completeness

Ensure the use case includes:
- Clear name and description
- Identified actors
- Basic flow of events
- Key alternative flows
- Pre/postconditions

## Output

Returns:
- Path to created use case file
- Use case ID (for tracking)
- Sections filled in

## Common Errors

| Error | Cause | Solution |
|-------|-------|----------|
| Template not found | Template path incorrect | Verify `docs-eng-process/templates/use-case-specification.md` exists |
| Invalid filename | Use case name has invalid characters | Sanitize filename, replace spaces with dashes |
| Missing actors | Actors not identified | Identify primary and secondary actors from vision/requirements |

## References

- Use Case Template: `docs-eng-process/templates/use-case-specification.md`
- Use Case Work Product: `docs-eng-process/openup-knowledge-base/core/common/workproducts/use_case.md`

## See Also

- [openup-create-vision](../create-vision/SKILL.md) - Define project vision first
- [openup-detail-use-case](../detail-use-case/SKILL.md) - Transform high-level use case into detailed scenarios
- [openup-create-test-plan](../create-test-plan/SKILL.md) - Generate tests from use cases
- [openup-elaboration](../../openup-phases/elaboration/SKILL.md) - Elaboration phase use case detail