Aisle Commerce

Aisle Commerce is a SaaS platform where each merchant gets their own storefront on their own domain. It is a Node monorepo: an Express SSR web app, an API gateway, twelve domain services, and a shared runtime package the services all build on.

The gateway is the interesting component. A request arrives and it decides whether the host is a platform host or a storefront host, asks store-service to resolve the domain, verifies the caller's token, then builds signed internal headers carrying request, actor and store context before proxying to the right service. Every downstream service validates that HMAC signature before it trusts any of it.

Services split by bounded context and each own their persistence: user, store, compliance, customer, product, cart, order, payment, billing, support, chat and notification, on ports 4101 through 4112.

Multi-tenancy is where commerce platforms leak. Every query, every cache key and every file path has to carry a tenant, and the moment one service trusts a tenant identifier that arrived in a header from the internet, one merchant can read another's orders.

The usual answer is to pass a tenant ID between services and hope nothing forges it. That works until a service is exposed directly, or an internal network stops being trustworthy, and then the tenant boundary was never real.

The second problem is events. Order confirmation depends on payment success arriving. A bus that silently drops a PAYMENT_SUCCEEDED event produces paid orders that never confirm and inventory that stays reserved forever — a failure nobody notices until reconciliation.