Send messages and search the user's received messages.
With the messaging domain, users can ask Siri to compose new messages or search for existing messages. For new messages, your extension handles the composition and sending of the user’s message through your service. Similarly, your extension handles searches directly and returns any results to SiriKit. After a search, the user can ask Siri to read the returned messages and mark them as read, which may result in more calls to your intents extension to update the message attributes.
On iOS, you can use an Intents UI app extension to display a custom message composition interface.