Claude Sonnet 4 now supports 1M tokens of context
Importance: 4 | # | anthropic, claude
Claude Sonnet 4 now supports up to 1 million tokens of context on the Anthropic API—a 5x increase that lets you process entire codebases with over 75,000 lines of code or dozens of research papers in a single request.
Long context support for Sonnet 4 is now in public beta on the Anthropic API and in Amazon Bedrock, with Google Cloud’s Vertex AI coming soon.
Anthropic has kinda cucked themselves here with their pro and max plans. The claude-code users will leave them bleeding dry if 1M context is brought to claude-code. It wouldn't be surprising if they had this ready for a while but couldn't figure out how to manage costs and now it's a bit too late and they are weirdly releasing for API only and not for subscribers.
Opus is good model. It isn't a reasoning model in the way openai's or google's are. Opus rarely thinks long and is super token effecient in general. Test time scaling is least used with Opus comared to other frontier models. It's crazy that this almost-not-a-reasoning-model is one of the very best right now.
Fitting everything into the 200k context while being super useful requires that you have high token efficiency - especially for code. Given that this is the first time we are seeing 1M context from Anthropic, it wouldn't be surprisnig if they are working on reducing inference cost by decreasing the model size and increasing test-time-compute.
I am also curious about how these 1M models are trained. So we have had 4.1 sonnet for a while now and they presumably took the 200k context length model and subsequently trained it on larger sentences? But then this would definitely affect the model behaviour even at smaller context lengths. It would make so much more sense if they leave the current model as is and release this new model with a different number - 4.2.