Claude opens message threads beta for long-running agents

Anthropic has opened message threads in public beta on the Claude Platform, letting agents send new messages without retransmitting their full conversation history. The company says requests containing 500,000 to 1 million tokens see median time before the first response token fall by about 35%. Developers start a thread with the full conversation, then send new messages with the previous response ID. Threads stay encrypted in memory and expire five minutes after the last request. Claude still reads the entire conversation each turn, so the feature does not reduce token usage or change standard token rates.