Function record 

pub fn record(
    block_id: &str,
    owner: u64,
    servers: Vec<ObservedServer>,
    at_ms: u64,
) -> bool

Keep what spawn owner of a pane reported, unless a newer spawn already reported or this one has exited. True when it changed, so the caller tells the panes (mcp:observed); a resumed turn’s init repeats it.