[BUG] `extraKnownMarketplaces` in `managed-settings.json` is ignored

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?

According to the docs, the extraKnownMarketplaces key should be available to be set in any settings file:

<img width="496" height="125" alt="Image" src="https://github.com/user-attachments/assets/d126b1d1-a6ac-4017-864d-90cc5975ffe5" />

So when I added a marketplace to /etc/claude-code/managed-settings.json:

{
  "extraKnownMarketplaces": {
    "company-tools": {
      "source": {
        "source": "git",
        "url": "<redacted>"
      }
    }
  }
}

I expected this to be added (or for the user to be prompted for this to be added) when they opened up claude. Instead no marketplaces are added, and users are not prompted to add marketplaces added in the managed settings. These marketplaces do not show up when looking at the TUI in /plugins.

What Should Happen?

Claude should either automatically set up marketplaces configured in extraKnownMarketplaces, or should prompt users to set up marketplaces configured there.

Error Messages/Logs

Steps to Reproduce

(Assuming a clean, new, claude code setup.)

1. Create a file in /etc/claude-code/managed-settings.json with the same content as above.
2. Replace <redacted> with a git url to a valid claude code marketplace.
3. Run claude
4. Run /plugin and navigate to Marketplaces

You'll be looking at a blank list (with maybe the exception of the default anthropic one, if applicable).

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.0.76

Platform

AWS Bedrock

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

_No response_