saitarrun Skill: Requirements & User Stories (INVEST)
INVEST Criteria — Making Stories Actionable
A well-written user story is INVEST-compliant:
- Independent: Story doesn't depend on another story (can be built in any order)
- Negotiable: Details can be discussed and refined (not cast in stone)
- Valuable: Delivers value to the end user (not just internal plumbing)
- Estimable: Engineer can estimate size (2-13 story points)
- Small: Fits in a single sprint (1-2 weeks max)
- Testable: Acceptance criteria are clear and provable
Story Format
## User Story: [Feature Name]
As a [role/persona]
I want to [action/capability]
So that [business value/outcome]
### Acceptance Criteria
- Given [precondition]
When [action]
Then [observable result]
### Edge Cases & Questions
- Q: What happens if [scenario]?
- Q: Should we support [case]?
### Definition of Done
- [ ] Code written and reviewed
- [ ] Acceptance criteria tests pass
- [ ] Documentation updated
- [ ] Performance tested (if relevant)
- [ ] Security review passed (if relevant)
Story Estimation
- Small (2-3 pts): Can be done in a day, low complexity, well-understood
- Medium (5 pts): Takes 2-3 days, some unknowns, requires design
- Large (8 pts): Takes full sprint, many unknowns, high risk
- Too Large (13+ pts): Break into smaller stories
Common Pitfalls
| Pitfall | Bad Example | Good Example |
|---|---|---|
| Not independent | "Add payment form" depends on "Add payment backend" | "Add payment form UI" + "Add payment API" (can be mocked) |
| Not valuable | "Refactor database layer" | "Enable payments via Stripe" |
| Not testable | "Code should be fast" | "Page load <2 seconds on 3G" |
| Too large | "Build entire user profile system" | "User can upload profile photo" |
| Unclear | "Handle edge cases" | "Given missing email, show validation error" |
Ambiguity Detection
Always ask these questions before starting work:
- Scope: Are there other features needed first? Any dependencies?
- Success: How do we know this is done? What's the test?
- Users: Who specifically benefits? All users or subset?
- Edge Cases: What happens if user has no data? Empty input? Slow connection?
- Performance: Are there speed requirements?
- Integration: Does this affect other features? APIs? Databases?