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Cloud Changelog
November 2, 2026 · Anthropic
Message threads in beta on the Messages API, sending only new messages
- Long conversations and agent loops on the Messages API can now send smaller requests and get a lower time to first token with message threads, in beta with the
message-threads-2026-08-12beta header. The API keeps the conversation on the server, so each later request sends only the new messages. A thread expires 5 minutes after its last request and is deleted no more than 1 hour after its last use. Message threads are available on the Claude API, Claude Platform on AWS, Claude Models on Google Cloud (Anthropic managed), and Claude in Microsoft Foundry.