Function watch_frame 

pub fn watch_frame(
    report: &Report,
    db_path: &str,
    rows: usize,
    colour: bool,
    history: &[f64],
    interval_secs: u64,
) -> String

One watch frame: the dashboard, then a burst sparkline when the 5-hour spend has moved since the previous refresh. No trailing newline — the caller appends its own status line and redraw_frame (cmduse’s) parks the cursor there, which is what lets the countdown rewrite a single line per second.