I’m trying to interface with a Chrome instance that has --remote-debugging-port=0 using DevTools Protocol and some Python websocket code a bit like this for communicating with it:

async def send(ws, command):
    await ws.send(json.dumps(command))
    async for message in ws:
        response = json.loads(message)
        return response


async def send_msg(url, msg):
    print(f"sending to url {url} with message {msg}")
    async with websockets.connect(url) as ws:
        response = await send(ws, msg)
        return response

Currently I can successfully navigate it to URLs, kill the instance, open new tabs, etc using their available protocol names (i.e. Browser.close, Page.navigate)

However, when trying to control anything under DOM (e.g. DOM.performSearch), I get the response:

{'id': 2, 'error': {'code': -32000, 'message': 'DOM agent is not enabled'}}

I’ve tried initialising the DOM by sending a packet like this before anything else:

{'id': 0, 'method': 'DOM.enable', 'params': {}}

but despite receiving a packet like this which would seem to suggest it worked:

response = {'id': 0, 'result': {}}

I still receive the same error:

{'id': 0, 'method': 'DOM.enable', 'params': {}}

I’ve even integrated very very long waits in case DOM.enable is taking a long time to initialise, but that doesn’t seem to solve the problem either.

Any ideas would be appreciated!