Claude API adds turn-scoped system messages in beta

BetaSep 1, 2026VerifiedAdded Sep 22, 2026

Setting clear_at next_user_message on a mid-conversation system message renders it for the current turn only, then keeps it in history at no token cost. Per-turn reminders no longer accumulate or invalidate the prompt cache and later thinking blocks.

Pricing

Read Anthropic's release notes

https://platform.claude.com/docs/en/release-notes/overview#september-1-2026

Summaries of vendors' own notes. Product names and logos belong to their owners; logos via logo.dev.

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