MCP enabled but no registry servers or tools discovered (no registry UI)

從 Settings → Tools → MCP 開始，檢查本機的 mcp.json 設定和 MCP 重新整理路徑。使用文件中說明的 GitHub.com Copilot Business 設定搭配 registry-only 模式，然後比較顯示 0 個伺服器和 0 個工具的重新整理記錄。設定之註冊表中允許的伺服器和工具能在 MCP UI 中被探索到，且沒有 MCP 重新整理錯誤，即表示完成。

Title
Copilot for Xcode: MCP enabled but always discovers 0 servers / 0 tools on GitHub.com (no registry UI)

Describe the bug
GitHub Copilot for Xcode shows MCP as enabled and triggers MCP refresh, but it never discovers any MCP servers or tools (Servers: 0, Total tools: 0). Our org has a private MCP registry configured in allow “registry-only” mode, with GitHub's MCP server in the allowlist. The same registry works on github.com browser Copilot chats and in other IDEs (VS Code, IntelliJ), but not in Copilot for Xcode.

In Settings → Tools → MCP:

• MCP is enabled
• “Available MCP Tools” is empty
• UI consistently reports “Servers: 0, Total tools: 0”

The only editable MCP configuration is a local mcp.json file (via “Edit Config”) containing a servers object. There is no UI to view/configure an MCP registry base URL for GitHub.com (non-GHES) accounts. Logs show refresh succeeds but results are always 0 servers / 0 tools, with no MCP errors.

Versions

• Copilot for Xcode: 0.46.0
• Xcode: 26.1.1 (17B100)
• macOS: 26.2 (Tahoe)

Steps to reproduce

1. Install Copilot for Xcode 0.46.0
2. Sign in with a GitHub.com Copilot Business account (non-GHES)
3. Open Copilot for Xcode Settings → Tools → MCP
4. Confirm MCP is enabled and “Available MCP Tools” is empty
5. Click “Edit Config”; observe default mcp.json contains "servers": {}
6. Enable Verbose Logging
7. Trigger an MCP refresh (activation or settings change)
8. Observe logs: refresh succeeds but servers/tools remain 0

Screenshots

• Tools → MCP showing MCP enabled and “Available MCP Tools” empty (“Servers: 0, Total tools: 0”)

• mcp.json opened via “Edit Config” showing "servers": {}

• Tools → Built-In showing built-in tools present (tools UI otherwise works)

Logs

Copilot policy updated: customAgent=true, mcp=true, subagent=true
Refreshing MCP server tools…
Refreshed MCP tools - Servers: 0, Total tools: 0, Server names: []

Additional context

• Occurs on GitHub.com Copilot Business (not GHES)
• No MCP-related errors/warnings during refresh; result is consistently 0 servers / 0 tools
• Logs also show an Apple Events permission error on activation: ‘Not authorized to send Apple events to System Events.’ (NSAppleScriptErrorNumber=-1743). seems unrelated