Anthropic released Claude Sonnet 4.5 on 29 September 2025. It says the model is strongest for coding, long-running agents, and using a computer. Price matches Sonnet 4: $3 / $15 per million input and output tokens.
Claude Code gets checkpoints so you can roll back. The API adds context editing and a memory tool. Paid Claude apps can run code and make files in the chat. The system card deploys the model under Anthropic’s ASL-3 standard as a precaution.
A drop-in replacement at the same price is a product decision. Whether it should run unattended on your machine is still yours.
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