Artifacts now flag content written by people outside your organization

What

Artifacts (Claude Code's shareable published pages/files) can be edited by multiple people, and previously the only distinction tracked was whether a file was "cowritten" or "foreign" to you. This release adds a more specific signal:

• Artifact and asset metadata, save/fetch responses, and tool results now carry a new outside_writer (also called outsideWriter or outsideOrg in some places) field, alongside the existing cowritten/foreign fields.
• When artifact tools (asset_list, asset_read, file_list, file_read, files_read, and artifact publish/read/db_read) return content flagged this way, the message shown now specifically says the file "may include content from a writer outside your organization," instead of the more generic "another person's page" wording.
• Artifacts containing HTML content published by an outside-organization writer now get a prompt-injection defense wrapper that tells the model to treat that content as untrusted data, not instructions, and forbids changing permissions or configuration based on it.
• Telemetry now records when this outside-writer condition is detected.

Why

This lets Claude Code warn more precisely when you're looking at content that came from someone outside your organization, rather than just a co-writer, and it hardens artifacts against prompt-injection attempts embedded in content contributed by outsiders.