​
Inbound group context

Group messages include a group field on the inbound Message: 
for await (const [space, message] of app.messages) {
  if (!message.group?.isGroup) continue;

  const chatId = message.group.chatId;
  const speaker = message.group.participant.id;
  await space.send(`Hi ${speaker}, noted in ${chatId}.`);
}

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Group management

Once a conversation is a group, use space.group for membership operations: 
const members = await space.group.participants();
await space.group.add("+15559876543");
await space.group.remove("+15551112222");
await space.group.setName("Friday lunch");
Group creation and advanced metadata (avatars, backgrounds) require cloud or dedicated iMessage lines — see iMessage messaging features.

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WhatsApp Business

WhatsApp Business is 1:1 only in Skyline today. Group operations are iMessage-only.