The page creates the voice once; each engine attachment only gives it that scene's action runner, pointer canvas and annotation events. Calls made during a switch wait for the incoming engine and are refused with ENGINE_SWITCHING when none attaches in time; results name the engine that answered, and the session hears engine-changed after a switch. The analyst's follow-up memory and layer enable times outlive one engine's runner. scripts/qa-voice-engine-switch.mjs drives a fake microphone and Realtime transport through the switches.
