Module 06 Summary

What this module established

Declare a response model on every endpoint. It is a security control, not formatting: without it the handler's return value is serialised whole, and a new internal field silently becomes public.

Carry forward

• Every error needs a stable machine-readable code. A client branching on prose breaks the first time someone fixes a typo.
• Declare the error responses in the contract. It tells callers what to handle and surfaces statuses you return unintentionally.
• Widening what you accept is safe; widening what you return breaks any client that switches on the value.

Before moving on

Move on when every endpoint has a response model, every error carries a stable code, and you can classify a change as safe or breaking.

Mark complete