Function summarize_windowed 

pub fn summarize_windowed(
    h: &SubMsPerfHarness,
    window: usize,
) -> Vec<SubMsBenchSummary>

Slice each stage’s chronological sample buffer into window equal-sized chunks and produce a SubMsBenchSummary per chunk. Useful for rolling-window p99 analysis - “how did p99 evolve across the run?”

Windows are sample-count-based, not wall-clock-based, since the harness doesn’t record per-sample timestamps. For wall-clock windows, ensure the workload runs at a roughly steady rate; then the i-th window approximates the i-th time slice.

Returns an empty vector if the harness has zero stages.