fix(orchestrate): graceful IPC disconnect to prevent race condition

[laynepenney]

Summary

• Fix race condition where readers/workers report "disconnected unexpectedly" even after successful completion
• Fix non-interactive mode (-P flag) where readline was closing prematurely
• Change socket.destroy() to socket.end() with proper drain handling
• Add 1-second timeout as safety fallback

Problem 1: IPC Disconnect Race

The IPC client was using socket.destroy() which immediately closes the socket without waiting for pending writes to complete. This caused a race condition:

1. Child agent sends task_complete message
2. Child immediately calls disconnect() which destroys the socket
3. Server receives close event before processing the completion message
4. Reader/worker marked as "disconnected unexpectedly"

Problem 2: Non-Interactive Mode Exit

In non-interactive mode (-P flag), readline was still being created. When stdin closed (non-TTY mode), readline's close event triggered handleExit() before the prompt was processed.

Solution

IPC Client

Use socket.end() with a drain wait to ensure pending writes complete:

async disconnect(): Promise<void> {
  await new Promise<void>((resolve) => {
    const timeout = setTimeout(() => {
      socket.destroy();
      resolve();
    }, 1000);

    socket.once('close', () => {
      clearTimeout(timeout);
      resolve();
    });

    socket.end(); // Graceful close
  });
}

Non-Interactive Mode

Skip readline creation when -P flag is used:

const isNonInteractive = Boolean(options.prompt);
if (!useInkUi && !isNonInteractive) {
  // Create readline only for interactive mode
}

Test plan

• Build passes
• All 2070 tests pass
• Orchestrate tests pass (14 tests)
• Non-interactive mode works: codi -P "what is 2+2?" → "Four"
• Readers spawn and errors are reported properly (not "disconnected unexpectedly")

🤖 Generated with Claude Code