MQTT Protocol Overview
Implemented. Source: docs/user-device-mqtt-contract.md (stream player, v1.0), docs/transmitter-mqtt-contract.md (transmitter, v1.0).
Topic Structure
Implemented. Source: docs/user-device-mqtt-contract.md §4, docs/transmitter-mqtt-contract.md §3.
Commands
Implemented. Source: docs/user-device-mqtt-contract.md §8, docs/transmitter-mqtt-contract.md §7–§8, §11.
Events — Status, Heartbeat, Log
Implemented. Source: docs/user-device-mqtt-contract.md §5–§6, §8a, docs/transmitter-mqtt-contract.md §4–§5, §9.
Device Registration & Claim
Implemented. Source: docs/transmitter-mqtt-contract.md §10, docs/user-device-mqtt-contract.md §9.
Transmitter Audio Uplink
Implemented. Source: docs/transmitter-audio-uplink-contract.md v1.0.
Error Handling & Reconnection
Implemented. Source: docs/user-device-mqtt-contract.md §3, §8, §8a, §9a, docs/transmitter-mqtt-contract.md §2, §4.