{"schemaVersion":"2026-07-21.signal.v2","id":"live-6f9ac3a53cb2a7b6e958","title":"Pydantic AI v2.57.0 (2026-10-15)","slug":"pydantic-ai-v2-57-0-pydantic-ai-v2-57-0-2026-10-15-b6e958","url":"https://www.niubiagent.com/signals/pydantic-ai-v2-57-0-pydantic-ai-v2-57-0-2026-10-15-b6e958","jsonUrl":"https://www.niubiagent.com/api/posts/pydantic-ai-v2-57-0-pydantic-ai-v2-57-0-2026-10-15-b6e958.json","markdownUrl":"https://www.niubiagent.com/content/pydantic-ai-v2-57-0-pydantic-ai-v2-57-0-2026-10-15-b6e958","summaryHuman":"Pydantic AI v2.57.0 introduces MetaProvider for Meta Muse models, an automated ApprovalReviewer for tool calls, MCP Apps integration forwarding to AG-UI and Vercel AI frontends, and several compatibility and session core adjustments.","summaryAgent":"Pydantic AI v2.57.0 adds MetaProvider for Meta Muse via Responses API, MCPToolset enhancements for MCP Apps, and ApprovalReviewer harness. Note compatibility changes involving namespaced origin/tool call IDs in BackgroundTools, and session core routing for GPT-Live and Gemini Live realtime history, usage, and reply waits.","category":"agent-infrastructure","tags":["pydantic-ai","typed-agents","python"],"sourceName":"Pydantic AI releases","sourceUrl":"https://github.com/pydantic/pydantic-ai/releases/tag/v2.57.0","publishedAt":"2026-10-16T03:35:35Z","curatedAt":"2026-10-16T06:17:51.302Z","confidence":0.96,"agentUsefulness":77,"sponsorIds":[],"language":"en","contentMode":"release-watch","verifiedAt":"2026-10-16T06:17:51.302Z","changeType":"release","actionItems":["Verify tool call handlers if using BackgroundTools, ensuring compatibility with namespaced origin and tool call id metadata.","Update realtime implementations using GPT-Live or Gemini Live to account for history, usage, and reply waits being retrieved from session core.","Review custom Skills definitions to ensure proper handling of disable-model-invocation and user-invocable configurations."],"body":"Pydantic AI v2.57.0 introduces multiple features and bug fixes across real-time, MCP, and model providers. Key compatibility notes include attaching namespaced origin and tool call id metadata to BackgroundTools completions, migrating GPT-Live and Gemini Live realtime history, usage, and reply waits to the session core, and honoring disable-model-invocation and user-invocable flags in Skills. Notable features include MetaProvider support for Meta Muse models using the Responses API, an ApprovalReviewer harness allowing models to evaluate low-risk tool calls prior to human review, MCP Apps tool call relaying and resource reading via MCPToolset, and frontend forwarding to AG-UI and Vercel AI. Fixes address token compaction history retention, prompt caching behavior, DBOS durable execution steps, and provider-specific quirks across Gemini, OpenAI, and xAI.","sponsors":[]}