[BUG] Artifact tool disappeared in 2.1.268 — worked through 2.1.263, feature code still in binary

### Preflight Checklist

- [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) 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?

The built-in `Artifact` tool (publishes a local HTML file at `https://claude.ai/code/artifact/`) is no longer exposed in ANY session mode since updating to 2.1.268:

- Not present in interactive sessions
- Not present in SDK/headless sessions or their subagents
- Not present in `claude -p` print mode (even with `--allowedTools Artifact`)
- `ToolSearch` deferred-tool lookup `select:Artifact,ArtifactData,ArtifactCheck,ArtifactComments` returns "No matching deferred tools found"

The artifact feature code is still present in the 2.1.268 binary — strings for the tool's actions (`publish`, `list_files`, `read_page_data`, `room_send`, `watch`), `code/artifact` URLs, and the "Unrequested Artifact Publish" consent rule are all there. So the feature appears to be feature-flag gated off rather than removed. No changelog mention of a removal.

### What Should Happen?

The Artifact tool should be available in interactive sessions as it was in 2.1.223–2.1.263 (verified working Aug 19 – Sep 10), or there should be a changelog/deprecation note if it was intentionally withdrawn.

Impact: previously published artifact URLs still render, but no new artifacts can be published and existing ones cannot be updated (republish by path or by `url`).

### Error Messages/Logs

```shell
ToolSearch "select:Artifact,ArtifactData,ArtifactCheck,ArtifactComments" -> "No matching deferred tools found"
claude -p --allowedTools Artifact "" -> model reports the Artifact tool is not in its toolset
```

### Steps to Reproduce

1. Update to Claude Code 2.1.268 (native install, macOS arm64).
2. Start an interactive session and ask Claude to publish a local self-contained HTML file as an artifact -> Claude reports it has no Artifact tool.
3. Same result from an SDK/headless session, from its subagents, and from `claude -p --allowedTools Artifact`.
4. Compare with session transcripts from 2.1.223 (Aug 19), 2.1.247 (Sep 6), 2.1.263 (Sep 10) on the same machine/account, where `Artifact` tool calls succeeded and returned: `Published at https://claude.ai/code/artifact/`

### Claude Model

Other

### Is this a regression?

Yes, this worked in a previous version

### Last Working Version

2.1.263

### Claude Code Version

2.1.268 (Claude Code)

### Platform

Anthropic API

### Operating System

macOS

### Terminal/Shell

Other

### Additional Information

Timeline on one machine/account: 2.1.223 (Aug 19) OK -> 2.1.247 (Sep 6) OK -> 2.1.263 (Sep 10) OK -> 2.1.268 (Sep 14) missing everywhere.

Possibly relevant: re-running the retained 2.1.263 binary (~/.local/share/claude/versions/2.1.263) in -p mode on Sep 14 ALSO reports the tool unavailable — consistent with either print mode never exposing it, or a server-side flag changing between Sep 10 and Sep 14.

Login: claude.ai subscription. OS: Darwin 25.6.0, arm64.