Your AI Feature Doesn't Fail at the Model. It Fails at the Handoff

Описание и применение

Рецепт автоматизации: защита AI‑фич от ошибок в передаче данных через FastAPI‑прокси, проверка auth и лимитов, тестирование границ.

AI features often fail not because of the model but due to integration layers such as auth, payload limits, and streaming handling.

The proxy successfully prevents handoff failures, ensuring the model never receives malformed requests and improving overall reliability.

Deploy a FastAPI proxy that checks auth header and message count.
Configure the proxy to forward requests to the upstream model and stream responses back.
Create a rehearsal script that sends test requests for missing auth, wrong token, oversized body, and happy path.
Run the rehearsal script to verify each boundary returns the expected status code.
Iterate on proxy logic until all tests pass.
Integrate the proxy into the production stack.
Monitor for boundary failures in production logs.

The model had done its job flawlessly, and the handoff had not.

Here is the smallest slice I could build that still crosses every boundary.