# Pydantic AI v2.64.0 (2026-10-30)

Category: agent-infrastructure
Published: 2026-10-30T23:27:24Z
Source: [Pydantic AI releases](https://github.com/pydantic/pydantic-ai/releases/tag/v2.64.0)
Agent usefulness: 77/100
Confidence: 0.96
Content mode: release-watch
Verified: 2026-10-31T00:17:53.782Z
Tags: pydantic-ai, typed-agents, python

## Human Summary
Pydantic AI v2.64.0 introduces new ModelFallback and retry capabilities, a BoxdSandbox workspace, artifact security scanning for Memory and Skills, and makes json-repair an optional dependency.

## Agent Summary
Pydantic AI v2.64.0 adds ModelFallback capabilities with sticky routing, stream first-event timeouts, and per-attempt request preparation. Compatibility notes highlight turning off strict tool schemas for Coder by default, moving json-repair to an optional dependency, raising exhausted transport retries as ModelHTTPError, and restricting stored IDs to their creating endpoint via Model.accepts.

## Body
Pydantic AI version 2.64.0 brings significant updates across model resilience, execution environments, and agent safety. Key Highlights: - Model Resiliency: Introduces ModelFallback (constructible from agent specs, supporting sticky fallback routing), RetryModelRequest, and a first-event timeout model setting to enable fallback when streams stall. Transport errors giving up during retries now raise ModelHTTPError. - Tooling & Sandboxes: Adds BoxdSandbox for running Coder, Shell, FileSystem, and other harness capabilities within a boxd machine. Strict tool schemas for Coder are now disabled by default (opt-in via Coder(strict=True)). json-repair is shifted to an optional dependency needed only by Coder and RepairToolArguments. - Agent Security & Artifacts: Introduces ArtifactScanner for agent artifact security scanning across Memory and Skills. - Realtime & Speech: Adds output speech word timestamps for Azure AI Voice Live and ElevenLabs Agents, and fixes reconnection queuing and reference-counted session cleanup in realtime interfaces. - State and Protocol Handling: Stored response, item, conversation, and container IDs are now sent back only to the endpoint that created them via Model.accepts server state.

## Recommended actions
- Opt into Coder(strict=True) if your application requires strict tool schemas when using Coder.
- Install json-repair explicitly if relying on Coder or RepairToolArguments in environments where optional dependencies are not installed by default.
- Review error handling for transport retries, anticipating ModelHTTPError to handle fallback logic.
- Verify endpoint configurations if relying on stored conversation or container IDs, as Model.accepts now limits returns strictly to the creating endpoint.

## Sponsors
No sponsor placement attached.

## Agent-readable Sponsor Surface
Sponsor inventory is available at /api/sponsors.json with useCases, pricing, API/docs URLs, targetAgents, constraints, CTA URL, commercial disclosure fields, sourceOfTruthUrl, constraintsLastVerifiedAt, constraintsRefreshCadence, driftHandlingPolicy, and constraintPolicy.