Browser Handoff

When a browser-automation script or agent hits a step only a human should do — login, 2FA, OAuth consent, payment, identity check — browser-handoff streams the live browser to an operator over the web, waits for them to finish, and gives control back to the caller. The resume condition can be a URL, element, or content match, or a plain-English description of the finished state that a vision model polls for — so an agent can describe 'done' in English instead of picking selectors. When the browser lives in a cloud substrate (Kernel, Browserbase, Steel) and the library runs on the developer's machine, a passthrough mode iframes the substrate's own live-view inside the operator's page — avoiding the ~30-second-per-keystroke round-trip cost of relaying every frame and every input over the WAN. Discord, Slack, Email, and Console notifiers ship in the box.