Function two_big_clusters

crates/kernel/src/shard.rs:2322–2336

Two tight clusters of `m` blocks each (intra-cluster delta cycles) joined by a single thin cross edge — large enough (`2m > COARSEST_TARGET`) to drive the full coarsen → uncoarsen path.

(m: u32)

    let p = two_clusters();
    let dir = std::env::temp_dir();
    let pid = std::process::id();
    let prof = dir.join(format!("ix_shard_rt_{pid}.ixprof"));
    let shard = dir.join(format!("ix_shard_rt_{pid}.ixes"));
    std::fs::write(&prof, p.to_bytes()).unwrap();

    let report = shard_esp(
      prof.to_str().unwrap(),
      2,
      0.10,
      1,
      Some(shard.to_str().unwrap()),
    )
    .unwrap();
    assert!(report.contains("shards=2"), "report was: {report}");

    let m = ShardManifest::from_bytes(&std::fs::read(&shard).unwrap()).unwrap();
    assert_eq!(m.shards.len(), 2);
    assert_eq!(m.total_cross_ingress, 1000);