Sovereign: a router that learns which model to trust without labels

Solibra built Sovereign, a router that sits between an application and model providers and learns per-request model choice from grades of its own finished work, with no answer key and no prior knowledge of the models. Across eight public benchmarks run against Claude Opus 5.5 and Claude Haiku 5.5, Sovereign spent 43% to 81% less than Opus on every benchmark, matched or beat Opus accuracy on USACO, LiveCodeBench and SATBench, and was more accurate than Haiku everywhere, by up to 55 points on USACO. On USACO its accuracy rose from 88% over the first 25 tasks to 97.7% by the end, passing Opus around task 150, and its grader agreed with the hidden answer key 95% of the time.