SL
Systems4 min read

The Best System Architecture Often Begins Outside the System

Database schemas and APIs are downstream of business rules. When the domain is misunderstood, clean implementation can still encode the wrong reality.

Understand the domain

Learn how money, approvals, ownership, accounts, transactions, and other operational concepts actually behave before turning them into fields and endpoints.

Identify invariants

Define what must remain true regardless of timing, user action, or implementation detail. These invariants give the system a stable reference when exceptions appear.

Make architecture an expression

Only then should the rules become records, APIs, transactions, events, and services. Architecture is most useful when it makes the domain clearer rather than hiding it.

Architecture is the technical expression of how well a team understands the business rule.

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