Langfuse adds TypeSafe’s Jev as an evaluator

Langfuse’s September 22, 2026 changelog adds TypeSafe’s Jev decision model as a judge in its evaluators. Jev does not generate text; it receives a state and typed questions, then returns typed answers with probabilities. Choice questions return categorical scores, while Score and Yes / no questions return numeric results. Langfuse says teams can use the evaluator to classify topics, assess frustration, and flag out-of-scope requests, PII, or policy violations. Questions in an evaluator run in parallel against the same state, and adding more questions has little effect on cost or latency. Jev is priced at $0.042 per million input tokens, and responses arrive in well under a second, according to Langfuse. Setup requires a TypeSafe API key; users define questions, map observation fields into state, test sample observations, and attach the evaluator to a rule.