Constant CAPACITY_PLATEAU_THRESHOLD 

pub(crate) const CAPACITY_PLATEAU_THRESHOLD: u64 = 3;

Consecutive non-rising reported levels (below target, no distress) before the counterparty’s store capacity is inferred. Small, but greater than one: a single flat sample is ordinary churn, and the cost of a false inference is under-supplying the counterparty, so the bar errs high.