Function render_message 

pub fn render_message(
    template: &str,
    session_ref: &str,
    prompt_file: &Path,
) -> RenderedMessage

Bind a message template’s placeholders in one pass, so no value’s own braces are re-scanned: the session reference Voro captured at dispatch, the file holding the message, and — for a template that forks — a freshly generated v4 UUID for the session the send opens. All are shell-quoted; the references are agent-opaque text, not tokens Voro may assume are bare.