Function sse_body 

fn sse_body(events: Vec<(&str, Value)>) -> String

Renders events as a Server-Sent Events body in the order given, stamping every data: object with its own event name as type, the way Azure repeats it. The chatbot reads the event: line to decide what the data: line after it means, so the pairing and the order are what make a round parse as a tool call or as text.