FastAPI

Beginner — What is FastAPI's role?

• It provides a Python HTTP service boundary with declared routes and data schemas.
• Pydantic validates input/output, while application dependencies and services enforce identity, permissions, and business rules.

Intermediate — When should a route be async?

• When it awaits compatible nonblocking I/O.
• Async does not make CPU work fast or turn a synchronous SDK into an async one.
• I choose client and execution boundaries deliberately.

Senior — Where should long extraction run?

• In bounded workers with durable jobs, retries, status, and resource isolation.
• FastAPI can start/check tasks or expose fast specialized operations; it should not keep arbitrary multi-minute processing alive solely through an open request.

Scenario — Node can call the LLM already. Why add FastAPI?

• Only for a concrete Python library, local model, numerical workload, or scaling boundary.
• Otherwise another service adds authentication, deployments, networking, contracts, and failures without meaningful benefit.