An LLM endpoint looks like a URL. In production, it is a policy surface. The first version of an AI feature calls a provider SDK directly, with an API key in an environment variable. That works until a second model, provider, team, fallback requirement, or finance question arrives. Then every application reimplements the same routing, retries, quotas, caching, and logging — each one differently.
The missing component is not another model server. It is the gateway in front of the models. This article covers that layer: routing, cache correctness, failure handling, and token-level cost control. The GPU and serving layers below it are covered in the previous article on inference infrastructure; here we stay above the model endpoint.