Module protocol 

Ryu Hardware Protocol (RHP) v1 — Rust mirror of the wire contract.

This is the node-side implementation of the SAME contract defined in apps/hardware/PROTOCOL.md §3. The WebSocket handler (apps/core/src/server/hardware_ws.rs, wired in a later phase) (de)serializes these types on each TEXT frame; BINARY frames carry Opus/JPEG payloads and are not modeled here.

Keep this in lockstep with the two sibling implementations:

• C (firmware): apps/hardware/firmware/shared/protocol/include/rhp_protocol.h
• TS (relay): packages/protocol/src/hardware.ts

Message type strings and field names are NORMATIVE. The serde attributes below are chosen so the emitted JSON matches the spec exactly:

• #[serde(tag = "type", rename_all = "snake_case")] makes the enum a { "type": "..." }-tagged union; snake_case yields camera_meta, hello_ack, tts_start, chat_delta, etc.
• Stt renames to stt, TtsStart/TtsEnd to tts_start/tts_end.

Structs

AudioFormat

Audio format descriptor (mic uplink in hello, TTS downlink in hello_ack).

Caps

Capability profile a device advertises in hello.

DeviceListItem

One entry in GET /api/hardware/devices.

DeviceUpdate

PATCH /api/hardware/devices/:id request body.

PairRequest

POST /api/hardware/pair request body.

PairResponse

POST /api/hardware/pair response body.

Enums

DeviceType

Physical device class. Wire: watch | necklace | desk.

Emotion

Face/emotion state driving the “Island eyes” renderer. Wire: neutral | listening | thinking | happy | sad | surprised | speaking.

ListenState

Chat-turn boundary marker. Wire: start | stop.

Mode

Device operating mode. Wire: idle | chat | ambient.

RhpClientMsg

Every control message a device/relay sends to the node, tagged on type.

RhpServerMsg

Every control message the node sends to a device/relay, tagged on type.

Surface

Display surface a display message targets. Wire: eink | lcd.

Functions

device_type_str

Wire string for a DeviceType (mirrors C rhp_device_type_str). Used by the SQLite registry, which stores the device class as its wire token rather than re-deriving it via serde.

parse_device_type

Parse a DeviceType from its wire string (mirrors C rhp_device_type_parse). Returns None for any unrecognized value.