Function eval_bitmap_query_stream 

pub fn eval_bitmap_query_stream<S, F>(
    source: S,
    query: BitmapQuery,
    range: Range<u64>,
    bucket_size: u64,
    direction: ScanDirection,
    budget: u64,
    on_metrics: F,
) -> BoxStream<'static, BitmapScanResult<Watermarked<u64>>>
where
    S: BitmapBucketSource,
    F: FnOnce(BitmapScanMetrics) + Send + 'static,

Evaluate a DNF BitmapQuery against a backend-provided bitmap source.

budget caps evaluated buckets across all dimension scans (see BitmapScanError::ScanLimit and BitmapScanMetrics). on_metrics fires exactly once when the eval stream is dropped.

Output emits Watermarked::Item(absolute_member_id) interleaved with Watermarked::Watermark(p) derived from the slowest leaf — sparse scans that match nothing still report progress at the rate sources advance.