MCP Rewatch

# Process Group Management Fix ## Problem When stopping processes, only the parent process was being killed, leaving child processes orphaned. For example: - Running `npm run dev` spawns npm as parent and Next.js server as child - Stopping only killed npm, leaving Next.js server running - This happened even when quitting Claude Code ## Root Causes 1. **No process group management**: Processes were spawned without `detached: true`, so they weren't in their own process group 2. **Only killing parent PID**: The stop method only sent signals to the parent process, not its children 3. **No cleanup on exit**: When the MCP server exited, it didn't ensure all managed processes were terminated ## Solution ### 1. Create Process Groups ```typescript const proc = spawn(command, args, { // ... detached: process.platform !== 'win32' // Create new process group on Unix }) ``` This puts the process and all its children in a new process group. ### 2. Kill Entire Process Group ```typescript // Kill process group using negative PID if (process.platform !== 'win32' && proc.pid) { process.kill(-proc.pid, 'SIGTERM') // Negative PID kills entire group } ``` Using negative PID with `process.kill()` sends the signal to all processes in the group. ### 3. Emergency Cleanup on Exit ```typescript process.on('exit', () => { // Synchronously kill all process groups for (const [name, managed] of processes) { if (managed.process && managed.pid) { process.kill(-managed.pid, 'SIGKILL') } } }) ``` This ensures no processes are left running when the MCP server exits. ## Platform Considerations - **Unix/Linux/macOS**: Full process group support using negative PIDs - **Windows**: Process groups work differently; falls back to single process killing - The `detached` option is only set on non-Windows platforms ## Testing To verify the fix: 1. Start a dev server that spawns children (like `npm run dev`) 2. Use `ps aux | grep node` to see all processes 3. Stop the process via MCP 4. Verify all child processes are also terminated 5. Quit Claude Code and verify no orphaned processes remain