Transport Layer

AccessoryManager abstracts BLE, TCP/IP, and serial transports behind a single interface. Views and services interact only with AccessoryManager — never with transport implementations directly.

Transport Implementations

Transports live in Meshtastic/Accessory/Transports/:

File	Protocol	Notes
`BLETransport.swift`	CoreBluetooth	Standard BLE connection to radios
`TCPTransport.swift`	Network.framework	Wi-Fi / TCP/IP to radios with networking
`SerialTransport.swift`	IOKit serial	macOS only; USB-serial adapters

Each transport conforms to a MeshTransport protocol that exposes connect(), disconnect(), send(data:), and a received publisher.

AccessoryManager Extension Map

Extension	Key Methods
`+Discovery`	`startScanning()`, `stopScanning()`, `peripheral(_:didDiscover:)`
`+Connect`	`connect(peripheral:)`, `disconnect()`, `centralManager(_:didConnect:)`
`+ToRadio`	`sendPacket(_:)`, `sendWantConfig()`, `sendWaypoint(_:)`
`+FromRadio`	`handleFromRadio(_:)`, `handleMeshPacket(_:)`
`+Position`	`startLocationUpdates()`, `sendPosition(_:)`
`+MQTT`	`connectMQTT()`, `publishPacket(_:)`, `mqttClient(_:didReceiveMessage:)`
`+TAK`	`sendCoT(_:)`, `parseTAKPacket(_:)`

Packet Flow (Inbound)

Radio (BLE/TCP/Serial)
  → Transport.received publisher
  → AccessoryManager+FromRadio.handleFromRadio(_:)
  → Decode protobuf (MeshtasticProtobufs)
  → Route by packet type:
      MeshPacket  → handleMeshPacket(_:)
      NodeInfo    → updateNodeInfo(_:)
      MyNodeInfo  → updateMyNodeInfo(_:)
      Config      → updateConfig(_:)
      ...
  → Write to SwiftData via MeshPackets @ModelActor
  → Publish changes via @Published properties (UI updates)

Packet Flow (Outbound)

View / Service
  → AccessoryManager+ToRadio.sendPacket(_:)
  → Encode to protobuf (ToRadio wrapper)
  → Transport.send(data:)
  → Radio

Adding a New Packet Type

Add the protobuf definition in the protobufs/ submodule.
Run ./scripts/gen_protos.sh.
Add a decode/dispatch case in AccessoryManager+FromRadio.handleFromRadio(_:).
Add a send method in AccessoryManager+ToRadio.swift.
Add a model property or SwiftData entity if the data needs to persist.
Write unit tests against the encode/decode round-trip.

Concurrency Notes

AccessoryManager is not @MainActor. Its @Published properties are observed from SwiftUI views on the main actor. Use await MainActor.run { } when updating published properties from background tasks or CoreBluetooth delegate callbacks.

Background persistence writes must go through the MeshPackets @ModelActor, not the main ModelContext.