WebRTC Echo Cancellation Integration Cheat Sheet

One-page reference: where echo cancellation sits in the WebRTC Audio Processing Module (AEC → NS → AGC) and the reference-signal rule; the getUserMedia echoCancellation and echoCancellationType switches; mobile hardware AEC on iOS (Voice-Processing I/O) and Android (AcousticEchoCanceler); the ERLE debug metric; the double-processing 'walkie-talkie' trap; and a decision checklist for when to add a neural canceller.