Workspace scaffold + spearhead step 1: browser talks WebRTC to the core, core terminates DTLS-SRTP, decodes Opus to canonical 16-bit PCM @24 kHz mono, echoes back. Proves the media core + the codec-to-PCM boundary (pre-paves the tap). Stubs lock the ADR-0002 fused-vertical boundaries for steps 2/5/6. Drafted in brainstorming session 2026-06-28.