Function fill_of 

fn fill_of(
    reported: Option<u8>,
    total_tokens: Option<u64>,
    effective_max_tokens: Option<u64>,
) -> Option<FillReading>

The fill a reading states, against the CLI’s own effective window.

Counted from the two numbers rather than taken from the reported share when both are there: the denominator has to be the effective window after any lowered auto-compact window, so a reading that names only its share is the fallback rather than the truth. None when neither says anything, so nothing fires on a guess.