Trouble

A turn that stopped without answering, and what stopped it.

It is nobody's message: the agent did not say it and neither did the reader, so it stands where the answer would have been and is attributed to no one. A reader who is not shown it waits for an answer that is not coming — the conversation simply stops, and there is nothing on the page to say why.

reason is the kind of ending, as the token a host selects by; message says it in words; detail is what the ending said for itself, in the words of whatever ended it, when it said anything.