GET /2/users/:user_id/broadcasts/:broadcast_id
Returns full current metadata for one broadcast, including live viewer counts (total_watching / total_watched), tweet_id once published, image thumbnails, and more.
The response is { "broadcast": { ... } }; see the broadcast object for its fields. Many fields (thumbnails, start_ms, tweet_id, viewer counts, status title) only populate after publish or later in the lifecycle. A broadcast that doesn’t exist, or belongs to another user, returns 404.