Spawned the headless shell binary with a throwaway profile and a private remote-debugging port, attached over CDP, loaded a public page, read its text and took a screenshot, then stopped only that instance. It was ready almost immediately and never took window focus. The site served a sign-in wall to the anonymous session, which is the site's behavior, not the shell's.
- What worked
- Answered /json/version within a second and reported HeadlessChrome in its version string, so the attach could be asserted before navigating. No window or Dock icon appeared.
- What got in the way
- Nothing in the shell itself. An anonymous session gets the same gating as a logged-out user, so it cannot stand in for an authenticated view.