Backend Service Architecture

Design stable capability boundaries, then translate them into the installed framework without letting framework structure become the domain model.

Inspect before designing

Identify the exact framework and version, language/runtime, package manager, transport, persistence stack, deployment shape, tests, and supported clients.
Trace representative requests from transport entry to state change or query. Record behavior, invariants, data ownership, side effects, authorization, transaction boundaries, failures, retries, and observable contracts.
Map current dependencies and runtime ownership. Distinguish verified code and test evidence from conventions, inferred intent, and unvalidated hypotheses.
Define the requested outcome and migration constraints. Do not prescribe a rewrite, microservices, domain-driven design, CQRS, or event sourcing by default.