Function select_mixed_range_lanes 

fn select_mixed_range_lanes(
    function: MixedRangeFunction,
    bounds: &[(usize, usize)],
    timestamps: &TimestampMillisecondArray,
    float_valid: &[bool],
    histogram_valid: &[bool],
    float_prefix: &[usize],
    histogram_prefix: &[usize],
    collector: &Option<PromqlAnnotationCollector>,
) -> Vec<Option<SampleLane>>

Selects the sample lane for each window and records policy-required annotations.