# Vercel — AI SDK 3.4

- Company: Vercel (vercel.com)
- Announced: 2024-09-20T13:00:00+00:00
- Category: developer-tool-release
- Coverage: not counted
- Announcement: yes
- Group: announcements
- Source: https://vercel.com/blog/ai-sdk-3-4
- Record: https://forck.live/items/20947-ai-sdk-3-4
- Subject: v0 / AI SDK / AI Gateway

Vercel released AI SDK 3.4, adding language model middleware for intercepting and modifying model calls, a data stream protocol enabling AI SDK UI to work with any backend, structured output modes, multi-step tool use, tracing improvements, and mock models for testing.

## Evidence

Verbatim from https://vercel.com/blog/ai-sdk-3-4:

> AI SDK 3.4 introduces language model middleware. Inspired by web middleware, language model middleware provides a modular way to intercept, modify, and enhance language model calls.

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Record: https://forck.live/items/20947-ai-sdk-3-4
Catalogue: https://forck.live/llms.txt
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