OptionalactionsOptionalfooterAlways-visible footer INSTEAD of the hover-revealed actions row (e.g. a feedback
control that must stay clickable without hovering). Assistant role only; wins over
actions when both are given.
user: right-aligned filled bubble (max 85% width, flattened bottom-right "tail" corner).
assistant: full-width prose block — no bubble chrome, content is typically rendered
markdown.
Action row under the content (copy button, timestamp, …) — hover-revealed.