System behavior
A flow depends on system rules
- System rules say what the product must do after user input.
- Data dependencies say what information must exist.
- Assumptions and open questions prevent fake certainty.
Weak versus strong
Rule
Weak
Comparison just works.
Strong
Comparison requires at least two shortlisted laptops.
Data
Weak
Show details.
Strong
Each laptop needs price, battery, weight, software fit, and availability.
Open question
Weak
Handle edge cases later.
Strong
What happens if availability changes after saving?