Architectural Coherence

Architectural coherence is the property of systems in which naming conventions are consistent, abstractions operate at the same level of detail, error handling reflects one philosophy, and design decisions feel like they emerged from the same mind. Fred Brooks identified conceptual integrity—a closely related concept—as the most important consideration in system design, arguing it could only be achieved when a single architect controlled all design decisions. For fifty years, this meant coherence was achievable only at small scale, because cognitive bandwidth limited how much a single mind could design. AI has made coherence achievable at large scale by allowing individual designers to implement complexity formerly requiring teams. The result is systems of unprecedented internal consistency—and unprecedented vulnerability to the systematic blind spots of the single mind that shaped them.