The encoder set OPUS_SET_INBAND_FEC, but the decoder never invoked FEC -- the loss path went DRED -> PLC, so FEC redundancy was emitted (and paid for in bitrate) yet never consumed. Wire FEC recovery into AudioEngine::on_playback between DRED and PLC: copy the next buffered packet once, try DRED, else (if the stream negotiated FEC) decode(next_pkt, ..., fec=true), else PLC. Recovery priority is now DRED -> FEC -> PLC. Add per-stream RemoteStream::fec_enabled_, captured from OpusParams in init_recv_stream. Docs (voice.md) updated to match. ctest --preset dev: 27/27 green. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>