v1.27.0 (2025-12-04)

What's Changed

• feat: Allow dynamic configuration of built-in tools via RunContext by @AlanPonnachan in #3600
• Support tool and resource caching for MCP servers that support change notifications by @dsfaccini in #3560
• Support raw CoT reasoning from LM Studio and other OpenAI Responses-compatible APIs by @dsfaccini in #3559
• Fix structured output with nested definitions with Gemini via OpenRouter by @dsfaccini in #3618
• fix: Copy extra_headers to allow model_settings reuse by @Wh1isper in #3628
• Add VercelAIAdapter.dump_messages to convert Pydantic AI messages to Vercel AI messages by @dsfaccini in #3392
• Disable use of tool_choice=required for deepseek-reasoner by @ZeroAurora in #3644
• Use custom reasoning field for OpenRouter by @xcpky in #3626

New Contributors

• @AlanPonnachan made their first contribution in #3600

Full Changelog: v1.26.0...v1.27.0