pub fn thought_message(reasoning: &str) -> MessageExpand description
Build a model-role Message carrying model reasoning as a
ThoughtContent, NOT as answer text.
The reasoning rides one ThoughtSummaryContent text part. Renders
downstream as a collapsed “thinking” line (TUI LineKind::Thought) and is
kept out of the assistant’s reply. Used for providers that stream reasoning
separately from the answer text. The control plane prunes reasoning from the
replayed prompt (it is never replayed to the provider).