Claude Code v2.1.201 Release: Sonnet 5 System Role Behavior Changed

Core summary

One sentence to understand this update

Claude Code v2.1.201 was released, notably changing Claude Sonnet 5 sessions to no longer use the mid-conversation system role for harness reminders.

Impact & opportunity

What this could mean

Developers using Claude Sonnet 5 should adjust their prompt engineering strategies to accommodate the change in system role handling, ensuring expected model behavior.