A messaging system includes a first messaging app on a first device and a second messaging app, on a second device, that can exchange messages (e.g. text messages, etc.), and the second messaging on can transmit content from a second extension app that operates with the second messaging app to the first messaging app that operates with a first extension app. The content can be opaque to the messaging app, but can be processed by the extension apps to display live, dynamic content in message bubbles in a message transcript of a conversation.