Pydantic AI Updates: September 23, 2026

1. v2.48.0 Added Same-Day Support for Opus 5.5, GPT-6 Sol, and GPT-6 Luna

Pydantic AI. The release lands claude-opus-5-5, gpt-6-sol, and gpt-6-luna model support within hours of the three launches, plus support for genai-prices 0.1.7 and the new OpenAI audio models, with the pricing dependency bumped again to 0.1.8 in the same release. For anyone routing across providers, that means cost accounting for the new models works without waiting for a follow-up patch. Source

2. Message IDs Now Survive a Round Trip Through Vercel AI and AG-UI Adapters

Pydantic AI. Two fixes address the same class of bug: UIMessage.id was being lost across Vercel AI load_messages and dump_messages, and Message.id was being lost across AGUIAdapter.load_messages and dump_messages. Both now round-trip, which matters for any UI that reconciles streamed updates against stored history by ID. Source