backend-implementation

Backend Implementation

Framework at the edges

Logic in plain testable use-cases; HTTP/ORM/framework in thin adapters. A controller full of rules is untestable.

Errors

Distinguish expected failures (validation/not-found/conflict) from bugs; typed results mapped to status at the edge. No bare catch-all.

Validate at the boundary

Parse-and-validate inputs into domain types; the core works with valid data.

Idempotency + outbox

Dedup key for retried work (webhooks/payments/async). Outbox: write the event in the same transaction as the state change so you never publish for a rolled-back write.