[BUG] VS Code IDE MCP getDiagnostics hangs indefinitely after WebSocket connection drops

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?

The mcp__ide__getDiagnostics tool hangs indefinitely when the WebSocket connection between Claude Code CLI and the VS Code extension drops. The tool does not timeout and continues waiting for a response for hours, causing Claude Code to freeze completely and become unresponsive.

Found 18+ occurrences in debug logs. In one case, the tool was stuck for 29001 seconds (~8 hours) without timing out.

What Should Happen?

• getDiagnostics should timeout after a reasonable period (e.g., 30-60 seconds)
• When WebSocket connection drops, pending MCP calls should be cancelled or fail gracefully
• Claude Code should remain responsive and continue working without IDE integration if the connection fails

Error Messages/Logs

Error Messages/Logs

  2025-12-0XT00:00:00.000Z [DEBUG] MCP server "ide": WS-IDE connection dropped after 0s uptime
  2025-12-0XT00:00:00.000Z [DEBUG] MCP server "ide": Calling MCP tool: getDiagnostics
  2025-12-0XT00:00:30.000Z [DEBUG] MCP server "ide": Tool 'getDiagnostics' still running (30s elapsed)
  2025-12-0XT00:01:00.000Z [DEBUG] MCP server "ide": Tool 'getDiagnostics' still running (60s elapsed)
  ...
  2025-12-0XT08:03:21.000Z [DEBUG] MCP server "ide": Tool 'getDiagnostics' still running (29001s elapsed)

Steps to Reproduce

Steps to Reproduce

1. Open VS Code with Claude Code extension installed
2. Start Claude Code CLI in the integrated terminal or external terminal
3. Use Claude Code normally for a while
4. Wait for the IDE WebSocket connection to drop (can happen due to VS Code reload, extension restart, or connection instability)
5. Send a prompt to Claude Code that triggers getDiagnostics call
6. Claude Code hangs indefinitely without responding

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.0.58

Claude Code Version

2.0.60

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

VS Code integrated terminal

Additional Information

VS Code Environment:

• Version: 1.106.3
• Commit: bf9252a2fb45be6893dd8870c0bf37e2e1766d61
• Date: 2025-11-25T22:28:18.024Z
• Electron: 37.7.0
• Chromium: 138.0.7204.251
• Node.js: 22.20.0
• V8: 13.8.258.32-electron.0

Related Issues:

• Related to but distinct from #3085 (JetBrains IDE timeout)
• Related to but distinct from #10813 (IntelliJ specific)

Suggested Fix:

1. Implement a timeout mechanism for getDiagnostics calls (e.g., 30-60 seconds max)
2. Cancel all pending MCP requests when WebSocket connection drops
3. Fail gracefully and allow Claude Code to continue without IDE integration