Function render_context_segment 

pub fn render_context_segment(contribution: &MemoryContextContribution) -> Value

Task B4 (spec §10.2, §5.3): build the synthetic wire message carrying one validated recall contribution. Pure — no engine state is read.

The contribution enters the request as ITS OWN separate message object — {"role": "user", "content": [{"type": "text", "text": …}]} — placed by the caller immediately BEFORE the real new user message. It is never merged into the user’s own content array (spec §5.3.2: memory is never presented as the user’s current words) and never becomes system policy (spec §5.3.3). The rendered text is neutralized here ([neutralize_rendered_text]) and wrapped in the host-guaranteed lower-authority boundary lines (spec §5.3.4).