bug: debug logs duplicated

[PandaWorker]

Bug Description

When launching debug mode, all events are written to logs 2-3 times.
Moreover, if you subscribe to the channel yourself, you will receive one event.

I understood that this is due to the fact that we subscribe to the event twice if we use undici, this is in undici inside the node and in undici as a dependency.

Reproducible By

NODE_DEBUG=undici node ./debug.js

import { request, Agent } from 'undici';

const dispatcher = new Agent({ connections: 1 });

async function execute() {
  const resp = await request('https://cdn.datatables.net/2.3.4/js/dataTables.min.js', { dispatcher });
  await resp.body.dump();
}

execute();

async function undici() {
  const { fetch} = await import('undici');
  const resp = await fetch('https://cdn.datatables.net/2.3.4/js/dataTables.min.js');
  await resp.arrayBuffer();
}

async function nodeUndici(){
  const resp = await fetch('https://cdn.datatables.net/2.3.4/js/dataTables.min.js');
  await resp.arrayBuffer();
}

// one debug logs
nodeUndici();

// duplicated debug logs
// undici();

Expected Behavior

Logs for a single query should not be duplicated.

Logs & Screenshots

Environment

node - v24.9.0 and v22.19.0
undici - 7.16.0

Additional context

[Uzlopak]

Yes, this is true. This is because of the use of the diagnostics channel.

[metcoder95]

The duplicated logs also has bad format.

I need to review this a bit deeper, but happy to review a PR for that.