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DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

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Claude Code v2.1.228 11 Aug 2026

SDK system messages report background tasks and turn context

Under the hood

Useful2 Signal2

SDK

Programs driving Claude Code through the SDK now see more detail about background work and turn context.

What

Programs driving Claude Code through the SDK get more detail about work running in the background.

Details

A new background_tasks_changed system message carries the list of active task ids.
Task status updates include is_backgrounded; task_notification gains a status.
turn_starting now carries a mode, plus the task_id when that mode is task-notification.

Evidence

background_tasks_changed

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.228 →