Forwarded from the inner composer — serialized draft on every value change.
Greeting text shown in the empty state. Set by host app via overlay/chat-area chain.
Draft staged into the composer on mount (see MessageInputComponent.initialDraft).
Show the built-in suggested-prompt chips. Hosts that don't want the default prompt vocabulary set false.
Pre-addresses the composer to an agent as a resolved mention pill (delegates to MessageInputComponent.InsertAgentMention). Returns false while the input isn't mounted — callers may retry.
Forwarded from the inner composer — persist-drafts save point.