Wire format unchanged — v0.5.1 interoperates with 0.5.0 both ways. (0.4.x remains incompatible; see the v0.5.0 notes.)Camera selectorReceive settings → camera. Field reports showed auto camera selection cannot be trusted on every device: a Huawei P30 Pro hands the browser its telephoto as "the" rear camera (blurry until you back across the room), and other phones hand over the front camera outright. The new select pins an exact device instead.The list fills in with real camera names once the camera has started — browsers return blank device labels until permission is granted, and a list reading "camera 1 / camera 2" is the guessing game the picker exists to end.Switching applies live, mid-transfer included: the running track is stopped, the new camera acquired, and decode state is untouched — frames pause during the swap and resume on the new lens. A camera that refuses to start falls back to the one that was running rather than leaving the receiver dead.Capability gray-outs (fps and width options the camera can't reach) now reset per lens — a telephoto's ceiling is not the wide lens's.