A reply the follower followed since it was sent stops being followed once the local copy holds its final record, so what streamed of it, which can include whole fetched pages, isn't kept in memory beside the record until the chat closes. The follower's tests run through useChat over the test store, rather than mounting useConversation by hand and holding the messages in state, and a test checks a finished reply's stream goes. specs/web-ui.md says the follower refreshes through the store's refresh intent so the store's hooks know nothing of streams, rather than merging the two.