[BUG] Dev channel shows "no MCP server configured with that name" for servers passed via --mcp-config

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?

Environment

• Claude Code: v2.1.295
• OS: Windows 11

Bug description

When an MCP server is provided through --mcp-config and used as a development channel, Claude Code always shows this warning under the "Channels (experimental)" banner:

server:crossroads · no MCP server configured with that name

The warning is wrong. The server is loaded in that same session: /mcp lists it as connected (under "Built-in MCPs") with all its tools, and channel notifications are delivered normally.
## Likely cause
The channel validation builds its set of known servers only from the config scopes enterprise, managed, user, project and local. When a server: channel is missing from that set, it reports "no MCP server configured with that name". Servers from --mcp-config (dynamic config) are never checked.

Impact

Tools that launch Claude Code with their own MCP server via --mcp-config, without modifying the user's ~/.claude.json or a project's .mcp.json, cannot avoid this false warning. Users read it as a broken setup. Adding the server to the user or project config is not a workaround: a plain claude started in that folder would then try te tool, and it would fail.

What Should Happen?

No warning, because the server is configured for this session via --mcp-config.

Actual The warning appears on every launch, although the server and the channel work.

Error Messages/Logs

Channels (experimental) messages from server:crossroads inject directly in this session · restart without --dangerously-load-development-channels to stop
server:crossroads · no MCP server configured with that name

Steps to Reproduce

1. Create mcp.json:

``json
{"mcpServers":{"crossroads":{"type":"stdio","command":"node","args":["-e","process.stdin.resume()"]}}}
``

1. In a trusted folder that has no crossroads entry in its user, project or local config, run:

`` claude --mcp-config mcp.json --dangerously-load-development-channels server:crossroads
``

1. Accept the "WARNING: Loading development channels" dialog.

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.295 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_