You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
ArtifactsArea: what it touches
ImprovementsKind: in v2.1.271,
ImprovementsSection of the release
What
When publishing an artifact fails because it references a capability Claude Code doesn't recognize, the error message now checks whether that capability actually exists in the current, up-to-date list of known capabilities. If it does, the error explains that the publish is pinned to an older contract version, either because the caller explicitly requested that older contract or because the artifact's own stored data specifies it.
Why
This turns a confusing "unknown capability" error into an explanation that the mismatch is due to version pinning, making it clear the fix is a version issue rather than a genuinely unsupported feature.
