Anthropic Claude Sonnet 4.5 Release Announcement

Anthropic has released Claude Sonnet 4.5, a state-of-the-art coding model. It achieves 61.4% on OSWorld (up from 42.2% four months ago) and maintains focus for 30+ hours on complex tasks. The pricing remains the same as Sonnet 4 at $3/$15 per million tokens. Additionally, Anthropic has shipped the Claude Agent SDK, which powers Claude Code, now public. This SDK includes memory management, permission systems, and subagent coordination. Claude can now also create Excel files, PowerPoint decks, and PDFs directly in the browser. The model is available via the `claude-sonnet-4-5` API as a drop-in replacement.