Pydantic AI AI Updates: August 15, 2026

1. Pydantic AI v2.31.0 Refines UI Event Streaming and Fixes FallbackModel Spans

Pydantic AI. Pydantic AI v2.31.0 lets developers build a UIEventStream without providing a run_input and gives AGUIEventStream its own thread_id and run_id properties for tracking execution context. The release fixes span attribution for FallbackModel so failures are recorded against the model that failed rather than the fallback wrapper, and resolves an issue passing the openai module through Temporal workflow sandboxes. The update was published on August 15, 2026 and incorporated a change from a new contributor. Source