Architect full MERN/Next-stack applications end to end — deciding the boundary between Next.js (frontend + server actions/API), MongoDB/Postgres data layer, and Express/standalone API services when one is needed. Use whenever the user is starting a full-stack project, asks "should this be a separate backend or Next.js API routes", is structuring a monorepo, or asks about the overall system architecture for a MERN/JAMstack-adjacent app.
