Architecture
also: software architecture, system architecture, architectural
The big-picture layout of your app: what the main parts are, what each one is responsible for, and how they connect.
The high-level structure of a system: its major components (frontend, backend, database, external services), their responsibilities, how data flows between them, and the key decisions that are expensive to change later, like the database or hosting model.
A building's floor plan. It doesn't show the paint colors, but it decides where the walls, plumbing and exits go. Moving a wall later is expensive.
Agents will propose architecture changes: new services, new databases, new layers. These are hard to undo. Knowing your current architecture lets you judge whether a proposal fits or just adds complexity.
Here's the current architecture: React frontend, one Express backend, one Postgres database. For notifications, I'd add a background job rather than a new service.
Before changing anything, describe this app's current architecture in a short list: the main parts, what each does, and how they talk to each other.
Thinking more complicated architecture is better architecture. For a small app, good architecture is usually simple. Complexity has to earn its place.