Cloudflare's persistent agent browser drops its logins after 10 idle minutes by default

The guarantee sits in one clause of the changelog: tabs, cookies and login session stay intact "while the browser session remains alive." ^[2] The failure path is a fresh browser plus a flag ^[4]. The flag, restarted: true, is the only signal the quoted text mentions. Of the old session it says: "The old tabs and login state are gone." ^[5]

That puts the check on the caller. The post's author builds a small keeper around the idea. Its ensure() method runs at the start of every turn and returns the browser, a restarted flag and a list of what was lost ^[11]. The comment above it reads: "Call this at the start of every turn. Never assume the old browser." ^[15]

Of the old fresh-browser-every-turn habit, the author wrote: "That is slow, but it is honest." ^[7] Of the new arrangement, the author wrote: "A browser that remembers is a feature. An agent that assumes it remembers is a bug." ^[13]

The demo is a model, and the author says so: "It is not how Cloudflare's browser tool works inside." ^[9] The clock is fake, and the 10-minute limit is copied from the documented default ^[10]. The model's idle timer counts from a lastUsed timestamp ^[12]. For that to transfer, the real timer would have to count from the last tool call. The quoted changelog does not say whether it does, or whether the default can be changed.

Restart is not the only hazard. Tabs are split by conversation, but the cookie jar is not ^[6]. The author's model closes that gap with a list of grants, each pairing a conversation with a site ^[16]. That list is the author's addition.

In our view the check belongs immediately before each side-effecting action, because a restart can land between any two turns. The post's demo includes a refund that assumed a dead login, and the keeper stops it ^[17]. For read-only browsing, logging in again on restarted: true is enough. For a refund, we'd stop the loop and ask a person.