Architecture is the set of decisions that are expensive to reverse. Which boundaries exist between services, where state lives, how systems talk to each other, what happens when one of them is down. Getting these approximately right early is worth more than getting everything else exactly right later.
We design against real constraints, the team you have, the budget you have, the systems you already run, rather than an idealised greenfield. The best architecture for a team of four is not the best architecture for a team of forty, and pretending otherwise produces systems nobody can operate.
The deliverable is a documented approach: component boundaries, data flows, integration points, failure modes, and the trade-offs behind each significant choice. Written so that the team building it can question the reasoning rather than just follow the diagram.
