Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
ElsewhereArea: what it touches
Internal ChangesKind: in v2.1.271,
Internal ChangesSection of the release
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_at and "turn-scoped system message"
a 400 error tied to the thinking_resumption beta 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.
