On 21 Oct 2026 Anthropic opened a research preview of Claude Duet, a new app where Claude works as a proactive agent. Anthropic says it was built for professionals and small business owners: each morning it looks across your email and calendar and sends a brief of what needs you, it can draft replies and follow-ups, and it keeps working in the cloud after you close the app. It is designed to ask before it sends a message, makes a payment, signs a document or deletes anything.