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← Back to all updatesPublished ·Anthropic• Minor
Mid-conversation system messages are available on Claude Fable 5, Mythos 5, and Opus 4.8 without beta headers.
The read
System-message changes can now be made mid-run on supported Claude models without beta-gated API handling.
The frame
This is an availability correction across Claude API, Amazon Bedrock, and Google Cloud for builders using mid-conversation controls.
Primary source
Anthropic →Keep reading
See what Nova3 builds →Related updates
- Aug 12, 2026Claude Managed Agents webhooks now cover environment and memory store lifecycle events without polling.
- Aug 12, 2026`version` is now optional when updating a Claude Managed Agents agent.
- Aug 12, 2026Anthropic is sunsetting the legacy Claude Console Workbench, with access ending on August 17, 2026.
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