What Claude Sonnet 5's 1M Context Window Actually Changes
Claude Sonnet 5 pairs a 1M-token context window with flat $2-per-million intro pricing — no long-context surcharge, unlike Gemini 3.1 Pro's step-up above 200K tokens. The window itself matters less than the economics of re-reading it: cache reads run up to 90% cheaper and skip Anthropic's input rate limits. Known caveats remain, from mid-window quality degradation to a 128K output cap. For PMs, the make-or-buy math on retrieval infrastructure just changed — corpora under a million tokens may no longer need a RAG pipeline at all.
