Setting headers for dynamically-created pages

[decaffeinatedio]

I'd like to be able to set custom headers and read network traffic when a new page is dynamically created, e.g. via a mouse click, rather than explicitly created by my application with create_page.

I'm trying to listen for .on('Target.targetCreated') events, but I believe these occur too late in the process, after headers can be meaningfully overwritten for the initial request.

[decaffeinatedio]

A little more information:

I was able to stop tabs from automatically loading by calling browser.command('Target.setAutoAttach', waitForDebuggerOnStart: true, autoAttach: true, flatten: true) and then patching in the following in the prepare_page method in Page to complete loading:

    def prepare_page
      command("Page.enable")
      command("Runtime.enable")
--> command("Runtime.runIfWaitingForDebugger") <---
      command("DOM.enable")
      command("CSS.enable")
      command("Log.enable")
      command("Network.enable")

      if use_authorized_proxy?
        network.authorize(user: @pr...

However, this only works for window.open. For normal clicks, the tab is stuck in a loading state and never (seemingly) receives the Runtime.runIfWaitingForDebugger signal.

Relevant Puppeteer discussion: puppeteer/puppeteer#3667

[route]

I think it's now addressed in master. But your original title says something about headers, but the description is about flatten mode. Hope it resolves all the issues :)