Client wall-clock ms when the entry was appended.
OptionalattachmentsFiles an assistant reply produced (CR-731) — from the live
companion.message envelope, or from history() on a restore (CR-729).
Absent when the reply produced none; render a download link from it.
One rendered line of the conversation, in arrival order.
'assistant'matches the industry role vocabulary and this package's own voice-call transcript +@pouchy_ai/react's ChatMessage (0.33.0 — was 'companion').