AI BriefingCC 2.1.128 Update
Key point
In CC 2.1.128, background agent instructions and the model catalog have changed.
Details
In CC 2.1.128, background-job behavior has moved from a separate system prompt into the built-in agent instructions. It has been organized to keep reporting progress, restate tool results, delegate investigative tasks, and use result:, needs input:, failed: status signals.
The onboarding guide sharing flow now includes rules for ONBOARDING.md upload based on ShareOnboardingGuide and returning a team share link. A RemoteTrigger API tool description has also been added, documenting functionality that handles scheduled remote agent routines without exposing OAuth tokens. The existing session memory update prompt, the summary.md template, and the background-job behavior prompt have been removed.
The Claude API documentation has also been broadly updated.
- Added refusal stop-details guidance for Python, TypeScript, C#, Go, Java, PHP, Ruby
- Enhanced programmatic error type guidance for Java, PHP, Ruby, and the HTTP error reference
- Added documentation for
BetaToolRunnerand Managed Agents support based onclient.Beta.Agents/Sessions/Environmentsfor C# - Reflected typed model constants, adaptive thinking syntax, and beta advisor tool parameters for Go
- Updated the Java SDK documentation version from 2.17.0 -> 2.27.0
In the model catalog, Claude Sonnet 4 and Claude Opus 4 are now marked as deprecated.
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