CarPlay Architecture

This page covers the implementation of the CarPlay feature. For the user-facing guide see CarPlay.

Components

Component File Description
CarPlaySceneDelegate Meshtastic/CarPlay/CarPlaySceneDelegate.swift CPTemplateApplicationSceneDelegate that builds and manages the two-tab UI
CarPlayIntentDonation Meshtastic/CarPlay/CarPlayIntentDonation.swift Donates incoming and outgoing INSendMessageIntent interactions so conversations appear in CarPlay Messages and Siri can read them aloud
SendMessageIntentHandler Meshtastic/Intents/SendMessageIntentHandler.swift Handles INSendMessageIntent — resolves recipients/channels and sends the message over the active transport
SearchForMessagesIntentHandler Meshtastic/Intents/SearchForMessagesIntentHandler.swift Handles INSearchForMessagesIntent
SetMessageAttributeIntentHandler Meshtastic/Intents/SetMessageAttributeIntentHandler.swift Handles INSetMessageAttributeIntent (mark as read)
IntentHandler Meshtastic/Intents/IntentHandler.swift Routes INIntents to the appropriate handler

Template Updates

The scene delegate subscribes to AccessoryManager.shared.$isConnected with a 300 ms debounce and calls updateSections(_:) on existing CPListTemplate instances rather than rebuilding the whole template tree. This minimises flicker during reconnects and avoids triggering CarPlay's rate-limit on template replacement.

Intent Donation De-duplication

Intent donations are de-duplicated per CarPlay session using an in-memory Set. This avoids repeated IPC calls to the intents daemon on every list refresh (which happens on a timer while CarPlay is connected).

When a new CarPlay session starts, the set is cleared and up to 50 unread messages are batch-donated so Siri can read them back on demand.

Adding a New Intent

  1. Create a handler in Meshtastic/Intents/ conforming to the appropriate INIntent protocol.
  2. Register the handler in IntentHandler.swift's handler(for:) switch.
  3. Declare the intent in Meshtastic.entitlements under com.apple.developer.siri.
  4. Add a usage description in Info.plist if the intent requires a new privacy permission.