[BUG] Stale connection pool after sleep/wake/network change causes ECONNRESET on next API call #37078

import os from 'os';

class NetworkMonitor {
  private lastInterfaces: Map<string, string[]> = new Map();
  private listeners = new Set<() => void>();
  private interval: NodeJS.Timeout | null = null;

  start(pollMs = 5000) {
    this.lastInterfaces = this.snapshot();
    this.interval = setInterval(() => {
      const current = this.snapshot();
      if (this.hasChanged(current)) {
        this.lastInterfaces = current;
        this.listeners.forEach(cb => cb());
      }
    }, pollMs);
    // Don't prevent process exit
    this.interval.unref();
  }

  stop() {
    if (this.interval) clearInterval(this.interval);
  }

  onNetworkChange(cb: () => void) {
    this.listeners.add(cb);
    return () => this.listeners.delete(cb);
  }

  private snapshot(): Map<string, string[]> {
    const ifaces = os.networkInterfaces();
    const result = new Map<string, string[]>();
    for (const [name, addrs] of Object.entries(ifaces)) {
      if (!addrs || name === 'lo' || name === 'lo0') continue;
      result.set(name, addrs.filter(a => !a.internal).map(a => a.address).sort());
    }
    return result;
  }

  private hasChanged(current: Map<string, string[]>): boolean {
    if (current.size !== this.lastInterfaces.size) return true;
    for (const [name, addrs] of current) {
      const prev = this.lastInterfaces.get(name);
      if (!prev || prev.join(',') !== addrs.join(',')) return true;
    }
    return false;
  }
}

class ApiConnectionManager {
  private networkMonitor = new NetworkMonitor();
  private lastSuccessfulRequest = Date.now();
  private maxIdleMs: number;

  constructor() {
    this.maxIdleMs = parseInt(
      process.env.CLAUDE_CODE_CONNECTION_IDLE_TIMEOUT || '60000', 10
    );
    this.networkMonitor.start();
    this.networkMonitor.onNetworkChange(() => {
      this.resetPool();
      debug('Network change detected — connection pool reset');
    });
  }

  async preFlightCheck(): Promise<void> {
    const idleMs = Date.now() - this.lastSuccessfulRequest;
    if (idleMs > this.maxIdleMs) {
      this.resetPool();
      debug(`Connection idle for ${idleMs}ms (threshold: ${this.maxIdleMs}ms) — pool reset`);
    }
  }

  onRequestSuccess() {
    this.lastSuccessfulRequest = Date.now();
  }

  private resetPool() {
    // For Bun: Bun.gc(true) + new fetch context
    // For Node/undici: dispatcher.close() + new Agent
    // Platform-specific implementation
  }
}

// Integration: call preFlightCheck() before each API request
async function* streamApiResponse(request, options) {
  await connectionManager.preFlightCheck();
  // ... existing API call ...
  connectionManager.onRequestSuccess();
}