Press j in the terminal running npx expo start, or open the dev menu (Ctrl+M in the emulator, or adb shell input keyevent 82) and choose Open DevTools; Metro opens the page in Chrome 1 or Edge. Under the hood, each app registers its JavaScript runtime with Metro's inspector proxy, which lists the targets:
curl -s localhost:8140/json/list...
"title": "com.anonymous.booknest (Google sdk_gphone64_x86_64)",
"description": "React Native Bridgeless [C++ connection]",
..."Bridgeless" confirms the New Architecture. Each entry carries a webSocketDebuggerUrl that any CDP client can use: the lane app's scripts/cdp.mjs evaluates expressions and records CPU profiles that way (Profiling BookNest). Its first connections were cut off with close code 1006, because Expo 6,418 's Metro accepts a debugger only when the Origin header names its own base URL, http://127.0.0.1:8140, not localhost:8140. Pressing j gets this right; when you open the frontend by hand or through a port forward, use 127.0.0.1.