Under the hoodTier: how much it should matter to you
2Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
API ErrorsArea: what it touches
ImprovementsKind: in v2.1.228,
ImprovementsSection of the release
What
Claude Code now reads a capability_rejected: marker with a reason token out of 400 and 413 responses, rather than only lowercasing the error text and searching it for phrases. Token matching uses a word boundary, so image_block no longer matches image_blockade. Prose matching remains as a fallback, so nothing changes against servers that do not send the marker.
Details
Reason codes include prompt_too_long, mid_conv_system, cache_control_field, thinking_signature, effort_unsupported, media_budget, max_tokens_context_overflow, and per-beta-header entries.
Evidence
capability_rejected:
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
