A media marker mechanism may be used to send, to a cloud service, up-to-date context regarding playback of a media content stream on a user device. The cloud service may insert a media content item into a media content stream and/or combine media content items into a media content stream. The cloud service may implement the media marker mechanism to tag a content item with metadata that can be read by the user device. The user device can play the streaming media content and, when the tagged content item plays, read the metadata and send it to the cloud service. The cloud service can use the metadata to enrich the media content delivery by, for example, providing a companion image that the user device can display while paying the tagged content item, providing a link to make the companion image clickable, handling requests referring to the media content, etc.