chat-log.

an append-only stream of messages that follows the newest one — unless the reader has scrolled up to read something, in which case it holds still and offers a jump back. track-list and article-list render a collection that happens to be ordered; this is a *stream*, and its whole contract is what happens when content arrives while you're looking at it, which is a behaviour neither of those has and neither should grow. groups consecutive messages from one sender, marks the viewer's own, and announces additions via role=log.