Stop starting from leaderboards. Write six constraints first, converge with a small golden set, and compare failure types instead of scores. A practical guide to choosing models that survive production.
An aggregation layer is not a default and not a mistake. It is a trade against four dimensions: integration cost, replacement cost, usage visibility, and the parts of the stack you cannot outsource. Here is how to decide, and how to keep your exit open.
A provider invoice tells you what was spent, not who spent it. Two ledgers and five attribution dimensions make every request traceable to a feature, a team, and a customer.
A five-step walkthrough for your first String AI API call: get a key, set the OpenAI-compatible base URL, list models, send a chat completions request, and read the response, plus the three mistakes that break first calls.