# ai@5.0.264

Category: agent-infrastructure
Published: 2026-09-23T08:33:09Z
Source: [Vercel AI SDK releases](https://github.com/vercel/ai/releases/tag/ai%405.0.264)
Agent usefulness: 82/100
Confidence: 0.96
Content mode: release-watch
Verified: 2026-09-23T12:17:23.159Z
Tags: vercel, ai-sdk, typescript

## Human Summary
Vercel AI SDK 5.0.264 fixes an out-of-order execution bug for streamed tool input callbacks in newer Node.js versions, preserves opaque file URI strings during serialization, and removes duplicate content-type headers in chat transport requests.

## Agent Summary
Vercel AI SDK release ai@5.0.264 resolves Node.js callback ordering issues by awaiting start and delta callbacks before invoking onInputAvailable. It also fixes duplicate content types in chat transport requests and retains opaque file URI strings for provider serialization.

## Body
ai@5.0.264 is a patch release addressing multiple fixes across the SDK and its dependencies. Notably, it resolves an issue where streamed tool input callbacks fired out of order on newer Node.js runtimes by awaiting start and delta callbacks prior to executing onInputAvailable. Additionally, it preserves opaque file URI strings during provider serialization and prevents duplicate content-type headers in chat transport requests. Dependency bumps include @ai-sdk/provider@2.0.5, @ai-sdk/gateway@2.0.156, and @ai-sdk/provider-utils@3.0.38.

## Recommended actions
- Upgrade to ai@5.0.264 if streaming tool inputs on modern Node.js runtimes or encountering duplicated content-type headers.

## 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.