Daily News · 1 min read

Pydantic AI Updates: September 25, 2026

pydantic-ai agents routing open-source

1. v2.50.0 Reworks How DecisionModel Picks a Route

Pydantic AI shipped v2.50.0 with three compatibility-breaking changes to model routing. DecisionModel is now asked which route to take by name, with one label per route, and the decision model’s built-in lean toward tool calls was replaced with an opt-in decision_route_threshold. ModelSelectionContext.messages now ends with the request actually being routed rather than trailing it, and a new ModelSelectionContext.prompt field was added. The release also exposes OpenAI’s service_tier in provider details. Source