Enabling 1M context window for Claude 4.6 Opus in Vercel AI SDK

Question

Do I need to pass any additional headers to get the 1-million context window in Opus 4.6, similar to what we do for Sonnet 4?

Code Example

import { streamText } from 'ai';
import { largePrompt } from './largePrompt.ts';

const result = streamText({
  headers: {
    'anthropic-beta': 'context-1m-2025-08-07',
  },
  model: 'anthropic/claude-4-sonnet',
  prompt: `You have a big brain. Summarize into 3 sentences: ${largePrompt}`,
  providerOptions: {
    gateway: { only: ['anthropic'] },
  },
});

Pricing

As for the pricing, does it incur any extra cost aside from what is already mentioned on the gateway when using the 1000K context window?