Pydantic AI v2.46.0 (2026-09-18)
Pydantic AI v2.46.0 introduces TypeSafeModel enhancements (tool arguments, union type resolution), runtime Choices and enum docstring helpers, TemporalDurability workflow stream event topics, and multiple fixes for realtime sessions and Bedrock adaptive thinking.
Why this signal matters
Pydantic AI v2.46.0 brings several features and bug fixes: Features: - TypeSafeModel: Supports filling tool arguments via Jev, selecting union output types prior to filling, and includes a typesafe boolean threshold for truth values. - Enums and Choices: Introduces the UseEnumMemberDocstrings mixin to describe Enum options via docstrings, and adds a runtime Choices helper for described options. - Temporal Integration: Adds an event stream topic to TemporalDurability for streaming agent events using Workflow Streams. - Realtime Sessions: Adds RealtimeSession.wait for playback() and pricing support to enable usage.cost and UsageLimits.cost. - Model Profiling & Evaluation: Adds text output support tracking to ModelProfile, permitting LLMJudge and GEval runs on models lacking it. Bug Fixes: - TypeSafeModel: Rejects option counts exceeding Jev's selection capability. - Realtime: Records failed ToolReturnPart when a tool raises, keeps speech and tool calls co-located in ModelResponse, and links late input transcripts to the correct user turn. - Toolsets: Dispatches tool calls using the live ToolDefinition in CombinedToolset and FunctionToolset. - Bedrock: Permits adaptive thinking with tool output and forced tool choice. - Model Matching: Resolves misclassification of gateway IDs as OpenAI o-series models. - Reliability: Raises ModelRetry on httpx2-rejected URLs in the web fetch tool, and re-arms test coverage on dataclass traversal resumption.
Actionable summary
Pydantic AI v2.46.0 updates TypeSafeModel to fill tool arguments via Jev and handle union outputs by selecting types first. It adds event stream topics to TemporalDurability, adds RealtimeSession.wait, enables runtime Choices, and resolves several bugs across realtime sessions, Bedrock tool choice, and tool call dispatching.
- Agent usefulness
- 82/100
- Confidence
- 96%
- Canonical data
- JSON + Markdown
What builders should check
- Upgrade to Pydantic AI v2.46.0 via pip/poetry/uv.
- If using RealtimeSession, verify playback handling and cost limit configurations.
- Adopt UseEnumMemberDocstrings or the Choices helper where dynamic or docstring-based option descriptions are needed.
- Configure event stream topics in TemporalDurability if streaming agent events over Temporal Workflow Streams.