Server-only integration (microservices stay off the browser)

We do not call internal microservices from the browser.

Why:

• security: secrets/tokens must not be exposed
• control: auth, rate limits, and validation enforced server-side
• stability: fewer client breakages when internal APIs change
• observability: consistent logs/traces on the server boundary

Recommended request flow

Boundaries

• Browser:
  • UI, user interactions
  • display errors
  • never holds microservice secrets
• Next.js server:
  • validation + auth enforcement
  • microservice integration
  • safe logging (no sensitive data)

Exercises

• content/exercises/04-trpc/01-protected-procedure.mdx