The solstone browser extension reaches the app over native messaging. The browser starts this binary in host mode, recognised from argv before any other startup work; it relays whole frames to the running app's same-user unix socket and holds no journal credential. The app keeps what it accepts in five-minute periods, answers a replayed batch as a duplicate, refuses new pages by name once its one bound is reached, and retires everything held for a journal it is no longer paired with. Finished periods are delivered as the `browser` source, and the journal mark gate holds them like any other upload. The whole path is compiled and tested in every build but is reachable only with the `browser` feature, which no owner build sets yet: without it there is no host mode, no endpoint and no browser registration. Capture segments under any stream folder other than the browser one are still the device's primary capture; browser periods are no longer sent as primary capture. The wire contract and frame crate are vendored unchanged from solstone-browser 16ad2636.