Module 02 Summary

What this module established

Routers handle HTTP, services hold the logic, and services import no FastAPI - that single constraint is what makes the logic callable from a worker, a job or a test without a request object.

Carry forward

• Declare settings as a typed class read once at startup, with safe defaults. Configuration errors then fail at boot rather than on a request at 3am.
• Never use --reload in production, and remember that multiple workers mean multiple copies of anything held in memory.
• Pin exactly, including transitive dependencies. Otherwise the build that passed CI is not the build that deployed.

Before moving on

Move on when a fresh clone with an empty environment installs and passes its tests.

Mark complete