Vercel moved the model name out of agent code.

Vercel AI Gateway now lets a team call a saved Virtual Model ID such as vmc/coding-agent instead of a provider model string. The saved configuration holds the underlying model, provider order, fallbacks, reasoning settings, reporting tags and requirements such as Zero Data Retention. Changing that configuration updates callers within minutes without a code change or redeploy. Settings on the Virtual Model override conflicting request settings, including fallback order and data-retention choices. ¹

That turns model selection into an operating decision with one change point. It also raises the cost of an untested edit: every agent using the alias can move at once, and provider-specific options stop applying when the alias switches providers. Vercel recommends a second candidate alias for evaluations before changing the production alias. ¹

Create the rollback path before the alias. Give one repeated task separate production and candidate IDs, pin their settings, and record output quality, latency, spend and the selected provider for the same inputs. Promote only after the candidate clears a written threshold; keep the old mapping ready for rollback. Also verify that request-level attempts to relax retention or change fallbacks are rejected by the saved policy. ¹