Under the hood
Artifacts now read back their stored capability declaration and show it to the model after publishing
What
After an artifact is published, Claude Code now reads back its stored declaration — the contract and capabilities the artifact service holds for it — and inserts it into the prompt in a labeled block, worded like "Stored for the live version, as the artifact service holds it: contract ... capabilities ...". Capability names are sanitized and escaped before being shown to the model, so they're treated as plain data rather than instructions.
Why
This lets the model see exactly what capabilities and contract are actually recorded for the live version of an artifact, rather than relying on what it assumed it had set.