Claude Code adds model configuration and updates thinking block handling

Claude Code adds model configuration options and updates the Messages API to handle thinking blocks with preserved thinking to protect against distillation. It also adds explanations for why Claude switched models during conversations with Opus 5 or Opus 5.5, alongside updates regarding the training data cutoff.

Official: https://support.claude.com/en/articles/12138966-release-notes

Did Claude Code reset today? Live status: https://quotatick.com/en/did-claude-code-reset-today

Did this change anything for your Claude Code usage? Reply with your plan and what you noticed.