Function page_of_span 

fn page_of_span(
    span: &TranscriptSpan,
    turns: u32,
    live: bool,
    budget: usize,
    cap: Option<(usize, &SessionSlot)>,
) -> Page

The page a span of transcript rows answers with, cursors and all.

The same page_within the held window is cut by, so a page below the seam is the same kind of page as one above it: whole turns where the span holds them, and within a running turn the run itself. The cursor is the byte of the page’s own oldest row, so the page below it seeks rather than searching; only a page that reached the file’s own first row carries none, which is the one answer a client stops on.