[Bug] Cursor IDE crashes with multiple concurrent Claude Code CLI instances

Bug Description
Title: Cursor IDE crashes when running multiple Claude Code CLI instances

Description:

Running multiple concurrent Claude Code CLI instances within Cursor IDE causes Cursor to crash/become unresponsive.

Environment:

• OS: macOS Darwin 25.1.0
• IDE: Cursor (please add your version)
• Claude Code: CLI version (run claude --version to get this)
• RAM: (add your system RAM)

Steps to Reproduce:

1. Open Cursor IDE
2. Open 2+ terminal instances within Cursor
3. Run claude in each terminal to start multiple Claude Code sessions
4. Work with Claude Code in multiple terminals simultaneously
5. Cursor becomes unresponsive and/or crashes

Expected Behavior:
Cursor should remain stable when running multiple Claude Code CLI instances, similar to how VS Code handles this.

Actual Behavior:
Cursor crashes or becomes unresponsive. Requires force-quit and restart.

Frequency:
(Add: Always / Often / Sometimes)

Workarounds Attempted:

• Running Claude Code in external terminal works fine
• Single instance in Cursor works fine
• Issue appears specific to multiple concurrent instances within Cursor

Notes:
This may be a Cursor-specific issue rather than Claude Code, but reporting here for visibility. Cursor is listed as a supported IDE in the Claude Code
documentation. Would be helpful to know if this is a known compatibility issue or if there are recommended resource limits for concurrent CLI instances.

Environment Info

• Platform: darwin
• Terminal: cursor
• Version: 2.0.65
• Feedback ID: e2444934-a5bb-4ede-983e-8b800e28b1e2

Errors

[{"error":"SyntaxError: Unexpected token 's', \"server.json\" is not valid JSON\n    at JSON.parse (<anonymous>)\n    at file:///Users/bachillah/.nvm/versions/node/v22.17.0/lib/node_modules/@anthropic-ai/claude-code/cli.js:60:693\n    at B (file:///Users/bachillah/.nvm/versions/node/v22.17.0/lib/node_modules/@anthropic-ai/claude-code/cli.js:8:6526)\n    at YZ0.<anonymous> (file:///Users/bachillah/.nvm/versions/node/v22.17.0/lib/node_modules/@anthropic-ai/claude-code/cli.js:4667:272)\n    at YZ0.Q [as _actionHandler] (file:///Users/bachillah/.nvm/versions/node/v22.17.0/lib/node_modules/@anthropic-ai/claude-code/cli.js:4372:528)\n    at file:///Users/bachillah/.nvm/versions/node/v22.17.0/lib/node_modules/@anthropic-ai/claude-code/cli.js:4376:3119\n    at file:///Users/bachillah/.nvm/versions/node/v22.17.0/lib/node_modules/@anthropic-ai/claude-code/cli.js:4376:1674\n    at async YZ0.parseAsync (file:///Users/bachillah/.nvm/versions/node/v22.17.0/lib/node_modules/@anthropic-ai/claude-code/cli.js:4373:4156)\n    at async pI5 (file:///Users/bachillah/.nvm/versions/node/v22.17.0/lib/node_modules/@anthropic-ai/claude-code/cli.js:4720:1623)\n    at async mI5 (file:///Users/bachillah/.nvm/versions/node/v22.17.0/lib/node_modules/@anthropic-ai/claude-code/cli.js:4656:1663)","timestamp":"2025-12-11T08:59:12.814Z"},{"error":"Error: 1: 1 \n    at zo3 (file:///Users/bachillah/.nvm/versions/node/v22.17.0/lib/node_modules/@anthropic-ai/claude-code/cli.js:1476:3956)\n    at async Fo3 (file:///Users/bachillah/.nvm/versions/node/v22.17.0/lib/node_modules/@anthropic-ai/claude-code/cli.js:1476:1579)","timestamp":"2025-12-11T08:59:14.769Z"}]