I shipped a production e-commerce system as a single monorepo: a Next.js 16 storefront, a Next.js 16 admin dashboard, and a NestJS API. English and Arabic with full RTL, guest checkout, and three AI features that live inside the codebase instead of being bolted on top.
This is the build log. The decisions I would defend, the ones that cost me a week, and what I would do differently.
Three apps, not one
The obvious move is one Next.js app with /admin routes behind a guard. I split it into three.
The storefront and the admin have almost nothing in common at the boundary. The storefront is public, SEO-critical, and cached aggressively. The admin is authenticated on every request, data-heavy, and never indexed. Sharing a build means the storefront pays for Recharts, the data grids, and the admin's client bundle even when nobody signs in.
