When a model returns a valid answer with weak confidence, an application often has only two choices: accept it or ask a person. Vercel AI Gateway’s confidence-based decision fallback adds a middle path for experimental_decide : run the configured fallback model when a successful decision matches a confidence condition. The feature is in beta, and a triggered fallback runs a second decision, so both stages are billed. That makes this a routing control, not a promise that the answer is correct...