Under the hood
Two new API error patterns are now specifically recognized: turn-scoped system messages and thinking-resumption rejections
What
Claude Code now recognizes two additional specific patterns among the 400-error responses the Claude API can return:
- a validation error related to
clear_atand "turn-scoped system message" - a 400 error tied to the
thinking_resumptionbeta feature header
Why
Sorting these into their own specific categories, rather than lumping them into a generic rejection, likely helps Claude Code decide when to retry a request or fall back to a different approach, and improves how these errors are tracked internally.