v1.51.0

pydantic/pydantic-aiv1.51.0Jan 31, 2026by DouweM

AI Summary

Adds customization options for the Chat UI and fixes issues with Gemini tool calls and Bedrock caching when messages end on non-text content.

Key Highlights

Added `html_source` parameter to customize Chat UI source
Fixed error when Gemini calls tools in agent run with instructions but no user prompt
Fixed Bedrock caching when user message ended on non-text content

New Features

`html_source` parameter for Chat UI

Full Release Notes

<!-- Release notes generated using configuration in .github/release.yml at main -->

## What's Changed
### 🚀 Features
* feat(ui): Add `html_source` parameter to customize Chat UI source by @madanlalit in https://github.com/pydantic/pydantic-ai/pull/3974
### 🐛 Bug Fixes
* Fix error when Gemini calls tools in agent run with instructions but no user prompt by @dsfaccini in https://github.com/pydantic/pydantic-ai/pull/4148
* Fix Bedrock caching when user message ended on non-text content by @DouweM in https://github.com/pydantic/pydantic-ai/pull/4152

## New Contributors
* @madanlalit made their first contribution in https://github.com/pydantic/pydantic-ai/pull/3974

**Full Changelog**: https://github.com/pydantic/pydantic-ai/compare/v1.50.0...v1.51.0