Function generate_with_overlay_unordered 

pub fn generate_with_overlay_unordered<'g, S: RowStream + 'g>(
    rows: S,
    constraint: Option<&Constraint>,
    overlay: Option<&Overlay>,
    last_pushed_epoch: u32,
    primary_key: &[ColId],
    predicate: Option<&RowPredicate>,
    multi_constraints: &[MultiConstraint],
) -> RowFlow<'g>

Unordered variant of generate_with_overlay (generateWithOverlayUnordered, memory-source.ts:885): NO start, add injected eagerly, remove suppressed by PK. Narrowing is constraint → multiConstraint → predicate (no startAt).