Claude 1M Context Now GA With No Long-Context Premium — Undercuts OpenAI (272K Threshold) and Google (200K) on Cost

simonwillison.net·high signal

Anthropic moved Opus 4.6 and Sonnet 4.6's 1M token context window to general availability with flat pricing across the entire window, eliminating the long-context surcharge tier that OpenAI applies above 272K tokens (GPT-5.4) and Google above 200K (Gemini 3.1 Pro). Simon Willison flagged this as the most practically significant aspect: competitors charge premium rates for extended context, making large document analysis and long-agentic-session costs unpredictable, while Anthropic's flat model removes the financial disincentive to using full context. This changes the cost calculus for builders processing large codebases, lengthy documents, or maintaining extended agent sessions.