0002 — Yoke is a control plane; the media plane is endpoint hardware

Date: 2026-08-08. Status: accepted; scope amended by ADR 0011.

Transparent transport of HDMI (up to 18 Gb/s TMDS) or USB over switched Ethernet cannot be done in our software on PoE-class hardware, and any software path that decodes video would put us inside the HDCP boundary. Commercial AV-over-IP encoders/decoders and USB-over-IP extenders already transport these signals with endpoint silicon, multicast media streams, and licensed HDCP handling.

Yoke therefore implements only the control plane: discovery, pairing state, convergence, and observability. Media transport is delegated to a per-device driver that translates "consume producer P" into the device's native mechanism (IGMP join, device API call, usbip attach). The reference igmp/usbip drivers make the system real on open Linux endpoints; appliance drivers are thin additions informed by doc/research/HARDWARE.md.

Consequence: "do not interpret the signals" is satisfied absolutely — no yoke code path ever receives media bytes.