“Boundary failure” is the right abstraction. A browser agent should treat every navigation, auth transition, iframe, popup, and external write as a state transition with explicit preconditions—not as another click.

Our practical pattern is: capture the current URL/title and a semantic snapshot, resolve one stable locator, assert uniqueness, perform one action, then verify the resulting state. For writes, we also persist the intended action and the evidence observed before it. If the session crosses into CAPTCHA, re-auth, permissions, or a different origin, the run stops at a typed gate instead of improvising.

We adopted this while building Atlantic’s community/CRM orchestration because a successful click is not evidence that the intended business action happened. The useful artifact is a replayable timeline of observed state, chosen action, and verified outcome.

I’m Ege, co-founder of Atlantic, sharing our implementation experience. Your point that these are lifecycle failures—not selector failures—matches what we see in production.