Think about how your first AI feature got built. Someone picked a provider, added their client library, and wrote the calls. That was the right decision at the time and it is now a fact about your architecture. The model name is in your source. The credential is in your configuration. The request and response shapes are the ones that vendor happens to use.
So when a better model arrives, or the price changes, or your legal team asks where the data goes, the answer is a project. Someone has to open the code, find every call, translate the differences, test it, and ship it. Multiply that by every service that talks to a model and the honest answer to "can we switch?" becomes "not this quarter".
That is not a model problem. It is a coupling problem, and it is solvable the way every other coupling problem has been solved: put something in the middle that speaks both sides.
The application asks. Something else decides.
Point your application at Squidder instead of at the provider. Keep your client library. Keep your code. What changes is who decides which model actually serves the request.
Your application can name a model, and it will get one it is allowed to use. Or it can name nothing at all, and get whichever model you have decided is the right default for that application. Either way the decision lives in a list you maintain, not in a deployment you schedule.
The consequence is small to describe and large to live with: changing vendor stops being a release. You edit the list. The next request goes somewhere else. Nobody opens an editor.
What that makes possible
Negotiate from a real position. A vendor conversation goes differently when switching is a configuration change rather than a quarter of engineering. You do not have to threaten to move. You have to be able to.
Survive an outage without a deploy. When a provider degrades, requests move down an order you set in advance. Your application does not know it happened, which is the point.
Give different work different models. The summarisation job and the customer-facing assistant do not need the same capability or the same price. That is a per-application decision and you can revisit it weekly.
Underneath those is the change that matters more than any of them: a model decision stops being permanent. You can give one application something you have not committed to, leave everything else where it is, and move it back in the time it takes to save a form. Reversibility is what lets a cautious organisation try anything at all. Whether the new model is good enough is a separate question, and proving it on your own traffic is usually what decides if the switch happens.
What this does not do
A gateway in the middle is a thing that can be wrong. If it translates between request shapes, then a parameter it does not know about is a parameter that does not reach the provider. That is a real risk and the answer is not to pretend otherwise: where you need a provider's exact behaviour, including a feature released last week, there is a path that forwards your request as you wrote it, untranslated. Use the convenient shape for the common case and the exact one when fidelity matters.
Anyone who tells you a translation layer is lossless has not maintained one.
What to try first
Take the least critical service you have that calls a model. Point it at Squidder, change nothing else, and confirm it still works. Then, without touching that service again, move it to a different provider and watch the cost line move.
That is a thirty minute exercise, and it answers the question you actually have, which is not "does this work" but "what does it cost me to change my mind later".