Module 07 Summary

What this module established

Declare shared request-time rules as dependencies: they run before the handler, appear in the docs, and cannot be forgotten by whoever adds the next endpoint under time pressure.

Carry forward

• Build expensive objects once behind a cached dependency and inject them. A module-level global cannot be replaced in a test.
• dependency_overrides is why you inject rather than import. The whole request path runs with the costly part replaced.
• Dependencies are for lifecycles and boundaries. Business logic put there becomes reachable only through HTTP.

Before moving on

Move on when your expensive dependency is built once, overridable in a test, and no dependency contains business logic.

Mark complete