[BUG] Artifact tool became disabled mid-session; previously published Artifact URLs return "Page not found"

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Summary

Partway through a long Claude Code session, the Artifact tool stopped being available ("Error: No such tool available: Artifact. Artifact is disabled for this session, in subagents as well as here."). Two Artifacts that had been successfully published earlier in the same session now return "Page not found" when opened in a browser.

Steps to reproduce

1. In a single ongoing session, published an Artifact multiple times successfully (a dashboard HTML page), each time getting a working share URL back.
2. Created a scheduled task (routine) whose final step was to publish an updated version of the same Artifact via the Artifact tool.
3. Ran the scheduled task via "Run Now". Its own execution reported the Artifact tool as disabled and could not publish.
4. Went back to the main chat session and tried to call the Artifact tool directly (both "publish" and "list" actions) — same error: Artifact tool disabled for this session and for subagents.
5. Opened both previously published Artifact URLs from earlier in the same session in a browser — both now show "Page not found".

Expected behavior

• The Artifact tool should stay available in the session that owns/published the artifacts.
• Previously published Artifact URLs should remain accessible unless explicitly deleted by the user.

Actual behavior

• Artifact tool is entirely disabled for the session (and for any subagents), with no way to re-enable it from within the session.
• Both previously published Artifact URLs (from the same session) now 404.

Impact

No underlying data was lost (source files are still on disk locally), but the shared/published dashboard link is now inaccessible to the end user, and there is no way to republish or verify artifact status from the affected session.

Environment

• macOS
• Claude Code

What Should Happen?

Expected behavior

• The Artifact tool should stay available in the session that owns/published the artifacts.
• Previously published Artifact URLs should remain accessible unless explicitly deleted by the user.

Error Messages/Logs

## Actual behavior
- Artifact tool is entirely disabled for the session (and for any subagents), with no way to re-enable it from within the session.
- Both previously published Artifact URLs (from the same session) now 404.

## Impact
No underlying data was lost (source files are still on disk locally), but the shared/published dashboard link is now inaccessible to the end user, and there is no way to republish or verify artifact status from the affected session.

Steps to Reproduce

Steps to reproduce

1. In a single ongoing session, published an Artifact multiple times successfully (a dashboard HTML page), each time getting a working share URL back.
2. Created a scheduled task (routine) whose final step was to publish an updated version of the same Artifact via the Artifact tool.
3. Ran the scheduled task via "Run Now". Its own execution reported the Artifact tool as disabled and could not publish.
4. Went back to the main chat session and tried to call the Artifact tool directly (both "publish" and "list" actions) — same error: Artifact tool disabled for this session and for subagents.
5. Opened both previously published Artifact URLs from earlier in the same session in a browser — both now show "Page not found".

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Clode Code

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_