Independence and Efficiency: What Makes a Boundary Worth Keeping
What are the two properties of a good software boundary?
A well-designed boundary has two properties. Independence means the component can evolve through a stable interface contract without coordination meetings with other teams. Efficiency means the cost of keeping the component alive stays lower than the value it generates, and it doesn't slow the rest of the system. Without both, the opposite takes hold: coordination meetings, instability, incidents that cascade, and a negative margin.
Why isn't a software boundary permanent?
There is no definitive cut. A boundary that is right this year may be wrong next year. Boundary identification is a continuous capital allocation discipline: every cut or merge is a choice driven by whether the component still serves demand efficiently and whether the margin justifies keeping it. What served as a monolith for the startup has to give way to modules when the business scales, and the organization has to keep assessing the fit.
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