/deep-research and /workflows commands unusable with official Claude auth, but work via third-party API (e.g. Kimi)

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?

When authenticating with official Anthropic/Claude authorization, the /deep-research and /workflows slash commands cannot be opened/initiated. When switching to a third-party API provider (e.g. Kimi), the same commands work as expected.

<img width="1473" height="359" alt="Image" src="https://github.com/user-attachments/assets/beb5eb20-8aab-408e-9617-eaabf7215cda" />

<img width="1489" height="342" alt="Image" src="https://github.com/user-attachments/assets/de24a866-4a67-4659-b381-c17a6de9ff38" />

What Should Happen?

/deep-research and /workflows should work the same way regardless of auth/provider, as long as the account has the relevant features enabled.

Error Messages/Logs

Steps to Reproduce

1. Open Claude Code and authenticate using official Claude authorization.
2. Try to run /deep-research and /workflows.
3. Commands fail to open / cannot initiate a run.
4. Switch the provider/API to a third-party option such as Kimi.
5. The same commands work correctly.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

v2.1.201

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_