[BUG] Artifact public sharing blocked: content scan never dispatched ('unscannable') for large artifacts — API error captured

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet (the closest reports are #79824 and its duplicates #85550, #82974, #79531, #81410, #82551 — none of them capture the underlying API error below)
• [x] This is a single bug report
• [x] I am using the latest version of Claude Code

What's Wrong?

Enabling "Anyone with the link" on a claude.ai/code Artifact fails with the generic UI message:

This version can't be shared publicly. Publish a new version or change the shared version, then try again.

Republishing new versions and switching the shared version does not help. Inspecting the failing network request reveals the actual cause, which no existing issue documents:

{
    "error": "frame: public serving requires the served version's content scan to be dispatched (unscannable)",
    "reason": "unscannable"
}

So public serving is gated on a server-side content scan, and for some artifacts the scan is never dispatched ("unscannable") — every version of that artifact is then permanently blocked from public sharing, with no indication of the real cause in the UI.

In my case the affected artifact is large (~2 MB, a page with a big inline minified JS payload published by Claude Code's design-canvas skill). A small static HTML artifact (~75 KB) published from the same session shares publicly without issues, which suggests a size or content-type limit in the scanner. Note that #85550 reports the same UI symptom with a ~25 KB static artifact, so "unscannable" may be one of several causes behind the same generic UI error.

Additional data point: before hitting the scan gate, the share dialog also blocked public sharing with "This Artifact offers file downloads, so it can't be shared publicly" while the page declared the downloads capability. Removing that capability got past the first gate and surfaced the scan error above.

What Should Happen?

Either the content scan should handle large/JS-heavy artifact versions so they can be shared publicly, or the share dialog should surface the real reason (e.g. "this version could not be scanned, public sharing unavailable") instead of the misleading "publish a new version and try again" advice, which cannot fix an unscannable artifact.

Error Messages/Logs

POST (share/public-serving request from the claude.ai artifact share dialog)
Response body:
{
    "error": "frame: public serving requires the served version's content scan to be dispatched (unscannable)",
    "reason": "unscannable"
}

Steps to Reproduce

1. In Claude Code, publish a large Artifact page (~2 MB) containing a large inline minified <script> payload (e.g. a design-canvas page produced by the bundled design skill).
2. Open the artifact on claude.ai, open the Share dialog.
3. Ensure no downloads capability is declared (otherwise a different blocker appears first).
4. Select "Anyone with the link".
5. UI shows "This version can't be shared publicly. Publish a new version or change the shared version, then try again."; the underlying request fails with the unscannable JSON above.
6. Republish (new versions, new labels) and retry — same result on every version.
7. Publish a small static HTML artifact (~75 KB) from the same session — public sharing works, confirming the account/session is otherwise able to share publicly.

Claude Model

Other: Fable 5 (claude-fable-5)

Is this a regression?

I don't know

Claude Code Version

2.1.241 (Claude Code)

Platform

Anthropic API