- STT: Replace MediaRecorder+Whisper with browser Web Speech API (ko-KR) Whisper base model hallucinated English for Korean speech; Chrome's built-in Google STT is far more accurate for Korean - TTS: Skip ffmpeg OGG conversion, return WAV directly from Piper Avoids OGG/Opus codec compatibility issues in browsers Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>