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Fixing Claude Code "IDE Disconnected" & Session Drops in Cursor

 There are few things more disruptive to a "flow state" than your AI tooling crashing mid-execution. For developers integrating Anthropic's new Claude Code CLI into Cursor IDE, a specific class of stability issues has emerged.

You trigger a complex refactor or a multi-file analysis, and suddenly the terminal hangs. You are met with an "IDE Disconnected" banner, a generic 500 error, or a silent failure where the CLI stops responding to input.

This is not a hallucination, and it is rarely a problem with the Anthropic API itself. It is a local environment synchronization issue. This guide details exactly why the connection drops and provides a robust, script-based solution to stabilize your Claude Code sessions within Cursor.

The Root Cause: Orphaned Daemons and Socket Timeouts

To fix the problem, we must understand the architecture of the tool. Claude Code (the CLI) does not operate strictly as a linear input/output binary. When you initialize it, it spins up a local background server (daemon) to handle state, file system context, and potentially Model Context Protocol (MCP) connections.

The "IDE Disconnected" error in Cursor typically stems from three specific conflicts:

  1. Ghost Processes: When you reload the Cursor window or put your computer to sleep, the terminal session sends a SIGTERM signal. Often, the main CLI process terminates, but the background daemon remains active, holding onto the port or socket. When you restart the terminal, the new instance fails to bind because the previous session is still "alive" in the background.
  2. MCP Handshake Failures: If you are using Claude Code as an MCP client, strict timeout limits in Cursor's internal terminal environment can kill the connection if the CLI takes too long to index a large codebase.
  3. Node Version Context: Cursor's internal terminal sometimes drifts from your shell's default Node.js version management (nvm/fnm), leading to runtime instability if the CLI relies on native bindings.

The Solution: A Resilient Wrapper Script

Manual intervention (running killall node) is clumsy and risky. The professional fix is a wrapper script that ensures a clean environment state before every launch.

We will create a shell function that:

  1. Identifies specific stale Claude Code processes.
  2. Gracefully terminates them.
  3. Force-kills them if they refuse to close.
  4. Verifies the Node environment.
  5. Launches a fresh instance with increased memory limits.

Step 1: Create the Wrapper Script

Add the following configuration to your shell profile. If you use Zsh (default for macOS and most Linux distros), edit your .zshrc. If you use Bash, edit .bashrc.

# Open your config file
nano ~/.zshrc

Paste the following robust function. This is designed to replace the standard claude command within your IDE context.

# ~/.zshrc

function cursor_claude() {
  echo "🔍 Checking for stale Claude Code processes..."

  # 1. Identify processes matching 'claude' CLI excluding the grep search itself
  # We use pgrep for a cleaner process ID extraction
  local PIDS=$(pgrep -f "claude-code")

  if [ -n "$PIDS" ]; then
    echo "⚠️  Found ghost processes: $PIDS"
    
    # 2. Attempt graceful termination (SIGTERM)
    echo "Attempting graceful shutdown..."
    kill -15 $PIDS 2>/dev/null
    
    # Wait up to 3 seconds for cleanup
    local TIMEOUT=3
    while [ $TIMEOUT -gt 0 ]; do
      if ! pgrep -f "claude-code" > /dev/null; then
        break
      fi
      sleep 1
      ((TIMEOUT--))
    done

    # 3. Nuclear Option: SIGKILL if still running
    if pgrep -f "claude-code" > /dev/null; then
      echo "🔥 Process unresponsive. Forcing kill..."
      pgrep -f "claude-code" | xargs kill -9
    fi
    
    echo "✅ Cleanup complete."
  else
    echo "✅ No stale processes found."
  fi

  # 4. Set Node memory limits to prevent heap crashes during large file ingestion
  # Claude Code can be memory intensive when indexing generic large repos
  export NODE_OPTIONS="--max-old-space-size=8192"

  # 5. Launch Claude Code
  echo "🚀 Launching Claude Code..."
  # Assuming 'claude' is in your global path. 
  # If installed via npm, this calls the binary.
  claude "$@"
}

Step 2: Reload Configuration

Save the file and reload your source without restarting the IDE:

source ~/.zshrc

Step 3: Usage

Inside your Cursor terminal, strictly use your new alias instead of the raw command:

cursor_claude

Deep Dive: Why This Fix Works

Handling Signal Traps

Standard CLI tools often fail to handle the SIGHUP (Signal Hang Up) that occurs when a terminal tab is closed or the IDE window reloads. By proactively hunting for claude-code process signatures via pgrep before launching a new instance, we prevent the "Port Already in Use" or "Socket Locked" errors that manifest as generic disconnects.

Memory Expansion

The line export NODE_OPTIONS="--max-old-space-size=8192" is critical. Cursor is an Electron app, and it manages resources aggressively. By default, Node.js processes might cap out around 2GB-4GB of heap memory.

When Claude Code attempts to ingest a context window containing 50+ files, it can spike memory usage. If it hits the V8 engine's limit, it crashes silently. The wrapper bumps this limit to 8GB, ensuring the CLI has breathing room to maintain the connection during heavy processing.

Edge Cases and Pitfalls

1. The "Too Many Open Files" Error

If your disconnects persist even with the wrapper, you are likely hitting the operating system's file descriptor limit (common in large monorepos).

The Fix: Check your limit in the terminal:

ulimit -n

If it returns 256 or 1024, it is too low. Add this to your .zshrc / .bashrc alongside the wrapper function:

# Increase file descriptor limit
ulimit -n 65536

2. Conflicting Extensions

Occasionally, the Cursor internal AI (Copilot++ / Tab key autocomplete) fights for focus with the Claude Code CLI input buffer.

If you notice input lag or dropped characters:

  1. Open Cursor Settings (Cmd + ,).
  2. Search for terminal.integrated.gpuAcceleration.
  3. Set it to off or canvas.
  4. Hardware acceleration in the terminal rendering can sometimes cause sync issues with heavy CLI output streams.

3. Authentication Loops

If cursor_claude launches but immediately asks for login repeatedly, the authentication token file is corrupted.

Run this reset sequence once:

# Clear the cached config
rm -rf ~/.anthropic/config.json 

# Re-authenticate cleanly
cursor_claude login

Conclusion

The "IDE Disconnected" error is rarely a network failure—it is a resource management conflict. By taking control of the process lifecycle using the wrapper script above, you ensure that every session starts with a clean socket and adequate memory.

This approach transforms Claude Code from a flaky experiment into a reliable driver for daily development within Cursor.

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