New Claude Model Runs 30-Hour Marathon To Create 11,000-Line Slack Clone

Anthropic's Claude Sonnet 4.5 ran autonomously for 30 hours to build a chat application similar to Slack or Teams, generating approximately 11,000 lines of code before stopping upon task completion. The model, announced today, marks a significant leap from the company's Opus 4 model, which ran for seven hours in May.

Claude Sonnet 4.5 performs three times better at browser navigation and computer use than Anthropic's October technology. Beta-tester Canva deployed the model for complex engineering tasks in its codebase and product features. Anthropic paired the release with virtual machines, memory, context management, and multi-agent support tools, enabling developers to build their own AI agents using the same building blocks that power Claude Code.

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