Artifact cannot be shared publicly: "This version can't be shared publicly" persists across republishes (Max plan)

Environment: Claude Code CLI on Linux, Max plan (individual). Artifact ID: b72906a4-60cb-44c7-a6bf-fbf91843cf64.

Description: An artifact published from a Claude Code session via the Artifact tool cannot be shared publicly. The share dialog shows: "This version can't be shared publicly. Publish a new version or change the shared version, then try again." The version picker briefly appears, is locked to "latest", and is not interactive.

The artifact: small (~25 KB) self-contained static HTML document with one inline SVG diagram. No scripts, no declared runtime capabilities, no MCP connectors — nowhere near size limits.

Steps to reproduce:

1. Publish an artifact from a Claude Code session (Artifact tool).
2. Open the artifact page, click Share, attempt to share publicly.
3. Error appears; version picker locked to "latest".

Attempted remediation (all failed):

• Republished new versions from the same session (multiple times) — same error.
• Tried the share flow in an incognito window — same error.
• Plan is Max, so the Team/Enterprise external-sharing policy does not apply.

Possibly related: #79824 (share fails across republishes), #82551 (locked version picker).