Where logic ends up matters

Misplaced logic rarely causes problems immediately.

Domain logic often quietly slips into systems that were never meant to own the question in the first place.

At the beginning it feels reasonable.
Pragmatic, even.

A small rule here.
A convenient check there.

Everything works.

The slow spread of responsibility

But over time something happens.

Business logic begins to spread across systems.

What once lived in one place now appears in several.

Responsibilities become blurred, and the boundaries between systems slowly fade.

At first the impact is small.
But eventually every change requires more coordination.

More teams need to align.
More systems need to be updated.

What once was simple becomes fragile.

The real problem

In the end, the issue is rarely the technology.

The real problem is where the logic ended up.

When domain logic lives outside the system that truly owns the capability, the architecture slowly loses its clarity.

And without clear ownership, systems become harder to evolve.

Architecture is about placement

Good architecture is not only about structure or technology choices.

It is about placing responsibilities in the right place from the start.

Because once logic begins to spread, pulling it back together is always harder than keeping it coherent in the first