Introduction: APIs in the AI Era

A team adds one new endpoint:

POST /responses

One request asks for a two-sentence answer. Another sends a large document and asks for a structured report. A third keeps the connection open while output arrives one piece at a time. All three are one request in an API log, but they do not consume remotely equal work.

That difference is real. It does not mean the rest of API design disappears.

An API for a model still has callers, resources, operations, fields, failures, permissions, limits, and costs. It still needs names that survive change