Problem

When Qwen Code restarts or reinitializes MCP servers, a race condition occurs that creates duplicate MCP processes instead of replacing them.

Root Cause Analysis

In McpClientManager.discoverMcpToolsForServer():

async discoverMcpToolsForServer(serverName, cliConfig) {
  const existingClient = this.clients.get(serverName);
  if (existingClient) {
    await existingClient.disconnect();
    this.clients.delete(serverName);
  }
  const client = new McpClient(...);
  this.clients.set(serverName, client);
  await client.connect();
}

Race condition window: Between disconnect() and connect(), the old MCP process is still running.

Evidence

kotolizator (PID 30400) → ACP (30452) → 2 MCP processes (30477, 30513) created 21 seconds apart

Environment

Qwen Code v0.15.6, Node.js v22.22.1, Linux