A boundary is a commitment

A capability owns what allows it to keep its promise: its behavior, its data, its rules, its failure conditions.

When responsibilities are difficult to locate, teams need to spend more time finding information and coordinating their decisions.

I recognize a useful boundary by what it lets me understand locally.

What comes in. What goes out. What remains guaranteed when a dependency is missing.

Drawing boxes is easy. Giving each one a responsibility it can actually fulfill requires choices.

The boundary begins with that commitment.