Constraint
A fixed rule you must obey in a design, such as a platform choice, compliance rule, timeline, or existing dependency.
Definition
A constraint is something you must obey in a design.
It is not negotiable without changing the problem.
Examples: team size, timeline, cloud, compliance, “must use the existing database.”
Why it matters
Constraints are what keep your design real. They are also how you justify decisions.
If you cannot explain a design choice in terms of constraints and requirements, it is probably taste.
Real-world examples
- Must integrate with the existing auth and identity system.
- Must run in the current cluster or cloud account.
- Must keep data in a specific region.
- Must emit audit logs for specific actions.
- Team size and timeline are fixed.