1M Context Window

Claude Opus 4.6 and Sonnet 4.6 support 1M token context with the context-1m-2025-08-07 beta header. Use it well or burn money for nothing.

When to Use

• You have a codebase, book, log bundle, or document set that fits in 1M tokens
• You need cross-document reasoning that chunked RAG can't deliver
• You're deciding between 1M-context vs a RAG pipeline
• You want to cache a giant system prompt / knowledge base across requests

Enabling 1M Context

import Anthropic from "@anthropic-ai/sdk";
const client = new Anthropic();