Your automation is not logged out: a missing `--cdp` flag started a second Chrome

A scheduled job of mine drives a real Chrome profile that stays signed in to DEV, because the API can read comments but cannot create them. One run came back with the dashboard replaced by the sign-in page: the log said it had opened https://dev.to/dashboard , and what it actually landed on was https://dev.to/magic_links/new , with zero links to my own profile anywhere in the DOM. The profile itself was fine. A probe against the debugging port at the same moment returned a live Chrome, and the dashboard fetched through that port rendered the account's own identity links normally. Two browsers, same machine, same minute, opposite answers. The three things worth checking first, and why they miss The session expired. That is the reflex, and it is also the one that makes you re-authenticate for no reason and burn the logged-in state you were trying to protect. Cookies got cleared by a Chrome update. Same family, same cost if you act on it. The debug port died and the tool fell back to something else. This one is close enough to be dangerous, because it names the right layer — which browser am I attached to — and then picks the wrong cause inside it. Where it actually goes wrong It is one argument. agent-browser attaches to an already-running Chrome when you pass --cdp <port> . Leave the flag off and it starts its own browser, with its own empty profile directory, and drives that one instead. Everything downstream still works — it navigates, waits, evaluates, returns a page. It just does all of that in a browser that has never logged in to anything. So the automation is not looking at an expired session. It is looking at a different browser's logged-out session, and reporting it in exactly the shape a real logout would take. The two failure modes do not look alike, and that is the trap Here is what I measured today, on Chrome 152.0.7977.65 with the current npx build. Pass the flag, but point it at a port nothing is listening on: npx -y agent-browser open "https://dev.to/