Pydantic AI Updates: May 25, 2026

1. BedrockModel now maps malformed_model_output and malformed_tool_use to FinishReason.error

Pydantic AI. A fix merged on May 25 extends the _FINISH_REASON_MAP in bedrock.py to cover two previously unmapped Bedrock Converse API stop reasons, malformed_model_output and malformed_tool_use, routing both to FinishReason.error. Before the change, the AWS Bedrock Runtime API could surface these values and Pydantic AI would silently fall back to finish_reason=None, leaving callers unable to programmatically distinguish a malformed output from a clean completion. The map previously carried seven of the nine documented stopReason values, and both new entries align with how other provider integrations treat malformed model output. Source

2. Dependabot sweep closes roughly 40 security alerts across docs site and Python extras

Pydantic AI. A maintenance pass merged on May 24 closes approximately 40 to 48 Dependabot advisories through minimal lockfile bumps and a single extras pin, grouped into four buckets. The docs site overrides protobufjs to ^7.5.8 to resolve ten npm alerts including a critical arbitrary code execution issue, while a new [tool.uv].constraint-dependencies block adds floors such as urllib3>=2.7.0 and lxml>=6.1.0 to force patched transitive Python packages without touching individual extras. Direct extras for vllm and pillow are bumped to patched versions, with the vllm floor moving to >=0.20.0 after an upstream fix landed in April 2026, and the workspace configuration raises pytest and pip floors for dev tooling. A review cycle reverted a prefect floor bump to follow library version best practices. Source