MCP server unavailable is reported as "waiting on ide" and hangs copilot-cli

Describe the bug

If you have an entry like this in your ~/.copilot/mcp-config.json

    "dummy": {
      "tools": [
        "*"
      ],
      "type": "http",
      "url": "http://bextop17:4000/mcp",
      "headers": {
        "Authorization": "Bearer token"
      }
    }

And the host is unavailable (it is in DNS but the system as a whole is unreachable) then copilot will hang on startup eventually showing the message "waiting on ide." IDE is not in use.

Important: using a non-existent dns name will NOT recreate this error. The host must be defined in DNS and not available. Using an existing host with a down service (system up, but port not) will NOT recreate this. My tests were confirmed by unplugging a system next to me's ethernet cable.

Affected version

GitHub Copilot CLI 1.0.81-6

Steps to reproduce the behavior

1. Define an mcp server for a system that has a valid dns name but is not on the network
2. start copilot cli
3. see error

Expected behavior

The cli should report the correct error message and not hang on a missing mcp server.

Additional context

This is on MacOS 15.7.7 (24G720) connecting to an mcp server on my local network which I had unplugged from the network for $reasons. This left the name in DNS but the system unavailable.

設定された MCP サーバーに接続する CLI の起動パスから始め、ネットワーク上で到達できない DNS 解決可能なホストを使って問題を再現します。完了条件は、CLI が MCP 接続の失敗を正確に報告し、ハングしたり誤って "waiting on ide." と表示したりせずに処理を続行することです。