fix: MCP servers allowed in settings do not show up in /mcp command

[laurentsimon]

TLDR

BUG. When a user configure their settings.json with:

"allowMCPServers": ["server1", "server2"],
"mcpServers": {
    "server3": {
     ...
    }
  }

running /mcp list does not show the blocked server: they disappear from the list.

This PR fixes the bug.

Dive Deeper

Reviewer Test Plan

Use a settings.jon with the example above. Verify that /mcp list shows the server3 as "blocked". Prior to this PR, server3 does not appear in the list.

[gemini-code-assist]

Summary of Changes

Hello @laurentsimon, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

I've addressed a bug where MCP servers specified in the allowMCPServers setting within settings.json were not correctly displayed by the /mcp list command. Previously, these servers would disappear from the list, but now they will correctly appear and be marked as "blocked" if they are not explicitly defined in mcpServers. This fix improves the accuracy of the server listing based on user configuration.

Highlights

• Bug Fix: Resolved an issue where servers listed in settings.json under allowMCPServers were erroneously hidden from the /mcp list output instead of being shown as blocked.
• Code Refactoring: Extracted the common logic for filtering allowed MCP servers into a new dedicated helper function, allowedMcpServers, to enhance code reusability and maintainability.
• Configuration Handling: Ensured that the application correctly processes allowMCPServers settings, leading to a more accurate and informative display of server statuses, including those that are blocked by configuration.

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[gemini-code-assist]

Code Review

This pull request fixes a bug where MCP servers that are not in the allowMCPServers list in settings.json would disappear from the /mcp list command output instead of being shown as blocked.

The fix involves extracting the logic for filtering allowed MCP servers into a new function, allowedMcpServers, and using it for both command-line arguments and settings. This correctly populates the blockedMcpServers list in both cases.

My feedback includes a suggestion to refactor the new allowedMcpServers function to improve its clarity and maintainability by avoiding side effects within an Array.prototype.filter() call.