fix(harness-claude-code): declare Claude Code's Monitor tool as built-in tool

[felixarntz]

Background

Claude Code can emit the native Monitor tool, but the harness did not declare it in its builtin tool set. That meant consumers could not recognize or type the tool as part of Claude Code's builtin capabilities.

Summary

• Declares Claude Code's Monitor tool with its input schema.
• Updates the builtin tool list regression test.
• Adds a patch changeset for harness-claude-code.

Checklist

• All commits are signed (PRs with unsigned commits cannot be merged)
• Tests have been added / updated (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)
• A patch changeset for relevant packages has been added (for bug fixes / features - run pnpm changeset in the project root)
• I have reviewed this pull request (self-review)

[github-actions]

🚀 Published in:

Package	Version
@ai-sdk/google	4.0.4 github npm
@ai-sdk/google-vertex	5.0.6 github npm
@ai-sdk/harness	1.0.12 github npm
@ai-sdk/harness-claude-code	1.0.12 github npm
@ai-sdk/harness-codex	1.0.13 github npm
@ai-sdk/harness-deepagents	1.0.11 github npm
@ai-sdk/harness-opencode	1.0.12 github npm
@ai-sdk/harness-pi	1.0.12 github npm
@ai-sdk/sandbox-just-bash	1.0.12 github npm
@ai-sdk/sandbox-vercel	1.0.12 github npm
@ai-sdk/workflow-harness	1.0.12 github npm