Vercel AI SDK adds support for GPT-5.6 with reasoning and prompt cache controls

Vercel released version 2.0.111 of its AI SDK with support for GPT-5.6, OpenAI's latest model. The update adds reasoning capabilities and prompt caching controls to the SDK's OpenAI provider.

The patch includes two key changes: GPT-5.6 model identifiers added to both the OpenAI provider and gateway implementations, and new controls for GPT-5.6's reasoning mode and prompt cache functionality.

Technical details

The update implements:

• GPT-5.6 model ID support across the SDK
• Reasoning mode controls for the new model
• Prompt cache control parameters
• Gateway implementation updates

The changes are contained in commits b4f8362 and 8549807 in the Vercel AI repository.

SDK integration

The Vercel AI SDK provides a unified interface for working with multiple AI providers including OpenAI, Anthropic, and others. This update maintains that abstraction while enabling developers to access GPT-5.6's new capabilities through the SDK's existing API patterns.

Prompt caching can reduce costs and latency by reusing previously processed context. The reasoning mode refers to OpenAI's chain-of-thought capabilities that show the model's internal reasoning process.

What this means

This is an infrastructure update, not a model release. OpenAI has not announced GPT-5.6, and the model is not publicly available. The SDK changes suggest either: (1) Vercel has early access for testing purposes, (2) the changes are preparatory for an upcoming release, or (3) the version number references internal or preview versions.

Developers using the Vercel AI SDK will be able to integrate GPT-5.6 immediately when OpenAI makes it available, without requiring additional SDK updates. The prompt caching and reasoning controls indicate GPT-5.6 will include features similar to those in Claude 3.5 Sonnet (prompt caching) and OpenAI's o1 series (reasoning mode).