diff --git a/src/obicompactvec/examples/compare_sparse_dense_count.rs b/src/obicompactvec/examples/compare_sparse_dense_count.rs
index 36040be7..15ce0cf0 100644
--- a/src/obicompactvec/examples/compare_sparse_dense_count.rs
+++ b/src/obicompactvec/examples/compare_sparse_dense_count.rs
@@ -13,20 +13,30 @@ use std::error::Error;
 use std::path::Path;
 use std::time::Instant;
 
-use obicompactvec::{PersistentCompactIntMatrix, PersistentSparseCompactIntMatrix, PersistentSparseCompactIntMatrixBuilder};
+use obicompactvec::{
+    PersistentIntMatrix, PersistentSparseCompactIntMatrix, PersistentSparseCompactIntMatrixBuilder,
+};
 
 fn main() -> Result<(), Box<dyn Error>> {
-    let layer_dir = std::env::args().nth(1).expect("usage: compare_sparse_dense_count <layer_dir>");
+    let layer_dir = std::env::args()
+        .nth(1)
+        .expect("usage: compare_sparse_dense_count <layer_dir>");
     let layer_dir = Path::new(&layer_dir);
 
     let t0 = Instant::now();
-    let dense = PersistentCompactIntMatrix::open(layer_dir)?;
-    println!("dense ouverte en {:?} ({} lignes x {} colonnes)", t0.elapsed(), dense.n(), dense.n_cols());
+    let dense = PersistentIntMatrix::open(layer_dir)?;
+    println!(
+        "dense ouverte en {:?} ({} lignes x {} colonnes)",
+        t0.elapsed(),
+        dense.n(),
+        dense.n_cols()
+    );
 
     let out_dir = tempfile::tempdir()?;
 
     let t0 = Instant::now();
-    let sparse = PersistentSparseCompactIntMatrixBuilder::build_from_dense(&dense, out_dir.path())?.finish()?;
+    let sparse = PersistentSparseCompactIntMatrixBuilder::build_from_dense(&dense, out_dir.path())?
+        .finish()?;
     println!("build_from_dense: {:?}", t0.elapsed());
 
     compare(&dense, &sparse)?;
@@ -36,7 +46,10 @@ fn main() -> Result<(), Box<dyn Error>> {
     Ok(())
 }
 
-fn compare(dense: &PersistentCompactIntMatrix, sparse: &PersistentSparseCompactIntMatrix) -> Result<(), Box<dyn Error>> {
+fn compare(
+    dense: &PersistentIntMatrix,
+    sparse: &PersistentSparseCompactIntMatrix,
+) -> Result<(), Box<dyn Error>> {
     let n = dense.n();
     let n_cols = dense.n_cols();
     assert_eq!(n, sparse.n(), "n mismatch");
@@ -63,7 +76,10 @@ fn compare(dense: &PersistentCompactIntMatrix, sparse: &PersistentSparseCompactI
             }
         }
     }
-    println!("comparaison case-a-case: {:?} ({total_cells} cellules)", t0.elapsed());
+    println!(
+        "comparaison case-a-case: {:?} ({total_cells} cellules)",
+        t0.elapsed()
+    );
 
     if let Some((slot, col, d, s)) = first_mismatch {
         eprintln!("PREMIER MISMATCH: slot={slot} col={col} dense={d} sparse={s}");
@@ -78,7 +94,7 @@ fn compare(dense: &PersistentCompactIntMatrix, sparse: &PersistentSparseCompactI
 /// for what's actually stored) — sparsity, singleton-row fraction, and the
 /// value-magnitude buckets this crate's overflow encoding is tuned around
 /// (< 127, < 255, >= 255).
-fn content_stats(dense: &PersistentCompactIntMatrix) {
+fn content_stats(dense: &PersistentIntMatrix) {
     let n = dense.n();
     let n_cols = dense.n_cols();
     let total_cells = n as u64 * n_cols as u64;
@@ -128,7 +144,10 @@ fn content_stats(dense: &PersistentCompactIntMatrix) {
         100.0 * singleton_rows as f64 / n as f64
     );
     if nonzero_cells > 0 {
-        println!("valeur moyenne (non-nulles): {:.2}", sum as f64 / nonzero_cells as f64);
+        println!(
+            "valeur moyenne (non-nulles): {:.2}",
+            sum as f64 / nonzero_cells as f64
+        );
         println!("valeur max:                  {max_value}");
         println!(
             "valeurs < 127:  {under_127} ({:.3}% des non-nulles)",
@@ -162,7 +181,7 @@ fn dir_size(dir: &Path) -> std::io::Result<u64> {
 fn compaction_stats(
     dense_layer_dir: &Path,
     sparse_dir: &Path,
-    dense: &PersistentCompactIntMatrix,
+    dense: &PersistentIntMatrix,
     _sparse: &PersistentSparseCompactIntMatrix,
 ) -> Result<(), Box<dyn Error>> {
     let dense_size = dir_size(&dense_layer_dir.join("counts"))?;
diff --git a/src/obicompactvec/src/intmatrix.rs b/src/obicompactvec/src/intmatrix.rs
index 7686bfc9..b30f239e 100644
--- a/src/obicompactvec/src/intmatrix.rs
+++ b/src/obicompactvec/src/intmatrix.rs
@@ -5,17 +5,19 @@ use std::path::{Path, PathBuf};
 use memmap2::Mmap;
 use ndarray::{Array1, Array2};
 
-use crate::bitmatrix::{fill_row_generic, par_col_reduce, pairwise2_matrix, pairwise_matrix, row_generic};
+use crate::bitmatrix::{
+    fill_row_generic, pairwise_matrix, pairwise2_matrix, par_col_reduce, row_generic,
+};
 use crate::builder::PersistentCompactIntVecBuilder;
-use crate::colgroup::{chunked_presence_count, ColGroup, MatrixGroupOps};
+use crate::colgroup::{ColGroup, MatrixGroupOps, chunked_presence_count};
 use crate::format::{HEADER_SIZE, OVERFLOW_ENTRY_SIZE};
 use crate::meta::MatrixMeta;
 use crate::reader::PersistentCompactIntVec;
-use crate::sparse_intmatrix::{is_present as sparse_is_present, PersistentSparseCompactIntMatrix};
+use crate::sparse_intmatrix::{PersistentSparseCompactIntMatrix, is_present as sparse_is_present};
 use crate::storage_kind::StorageKind;
 use crate::tempbitvec::{TempBitVec, TempBitVecBuilder};
 use crate::tempintvec::{TempCompactIntVec, TempCompactIntVecBuilder};
-use crate::views::{nonzero_triples, IntSliceView};
+use crate::views::{IntSliceView, nonzero_triples};
 
 pub(crate) fn col_path(dir: &Path, col: usize) -> PathBuf {
     dir.join(format!("col_{col:06}.pciv"))
@@ -25,7 +27,7 @@ pub(crate) fn col_path(dir: &Path, col: usize) -> PathBuf {
 
 pub struct ColumnarCompactIntMatrix {
     cols: Vec<PersistentCompactIntVec>,
-    n:    usize,
+    n: usize,
 }
 
 impl ColumnarCompactIntMatrix {
@@ -38,11 +40,17 @@ impl ColumnarCompactIntMatrix {
     }
 
     #[inline]
-    pub(crate) fn n(&self)      -> usize { self.n }
+    pub(crate) fn n(&self) -> usize {
+        self.n
+    }
     #[inline]
-    pub(crate) fn n_cols(&self) -> usize { self.cols.len() }
+    pub(crate) fn n_cols(&self) -> usize {
+        self.cols.len()
+    }
     #[inline]
-    pub(crate) fn col(&self, c: usize) -> &PersistentCompactIntVec { &self.cols[c] }
+    pub(crate) fn col(&self, c: usize) -> &PersistentCompactIntVec {
+        &self.cols[c]
+    }
 
     #[inline]
     pub(crate) fn row(&self, slot: usize) -> Box<[u32]> {
@@ -63,34 +71,64 @@ impl ColumnarCompactIntMatrix {
     }
 
     pub(crate) fn partial_bray_dist_matrix(&self) -> Array2<u64> {
-        pairwise_matrix(self.n_cols(), |i, j| self.col(i).partial_bray_dist(self.col(j)))
+        pairwise_matrix(self.n_cols(), |i, j| {
+            self.col(i).partial_bray_dist(self.col(j))
+        })
     }
     pub(crate) fn partial_euclidean_dist_matrix(&self) -> Array2<f64> {
-        pairwise_matrix(self.n_cols(), |i, j| self.col(i).partial_euclidean_dist(self.col(j)))
+        pairwise_matrix(self.n_cols(), |i, j| {
+            self.col(i).partial_euclidean_dist(self.col(j))
+        })
     }
-    pub(crate) fn partial_threshold_jaccard_dist_matrix(&self, threshold: u32) -> (Array2<u64>, Array2<u64>) {
-        pairwise2_matrix(self.n_cols(), |i, j| self.col(i).partial_threshold_jaccard_dist(self.col(j), threshold))
+    pub(crate) fn partial_threshold_jaccard_dist_matrix(
+        &self,
+        threshold: u32,
+    ) -> (Array2<u64>, Array2<u64>) {
+        pairwise2_matrix(self.n_cols(), |i, j| {
+            self.col(i)
+                .partial_threshold_jaccard_dist(self.col(j), threshold)
+        })
     }
     pub(crate) fn partial_relfreq_bray_dist_matrix(&self, col_sums: &Array1<u64>) -> Array2<f64> {
         pairwise_matrix(self.n_cols(), |i, j| {
-            self.col(i).partial_relfreq_bray_dist(self.col(j), col_sums[i] as f64, col_sums[j] as f64)
+            self.col(i).partial_relfreq_bray_dist(
+                self.col(j),
+                col_sums[i] as f64,
+                col_sums[j] as f64,
+            )
         })
     }
-    pub(crate) fn partial_relfreq_euclidean_dist_matrix(&self, col_sums: &Array1<u64>) -> Array2<f64> {
+    pub(crate) fn partial_relfreq_euclidean_dist_matrix(
+        &self,
+        col_sums: &Array1<u64>,
+    ) -> Array2<f64> {
         pairwise_matrix(self.n_cols(), |i, j| {
-            self.col(i).partial_relfreq_euclidean_dist(self.col(j), col_sums[i] as f64, col_sums[j] as f64)
+            self.col(i).partial_relfreq_euclidean_dist(
+                self.col(j),
+                col_sums[i] as f64,
+                col_sums[j] as f64,
+            )
         })
     }
-    pub(crate) fn partial_hellinger_euclidean_dist_matrix(&self, col_sums: &Array1<u64>) -> Array2<f64> {
+    pub(crate) fn partial_hellinger_euclidean_dist_matrix(
+        &self,
+        col_sums: &Array1<u64>,
+    ) -> Array2<f64> {
         pairwise_matrix(self.n_cols(), |i, j| {
-            self.col(i).partial_hellinger_euclidean_dist(self.col(j), col_sums[i] as f64, col_sums[j] as f64)
+            self.col(i).partial_hellinger_euclidean_dist(
+                self.col(j),
+                col_sums[i] as f64,
+                col_sums[j] as f64,
+            )
         })
     }
 
     pub(crate) fn append_column(dir: &Path, value_of: impl Fn(usize) -> u32) -> io::Result<()> {
         let mut meta = MatrixMeta::load(dir)?;
         let mut b = PersistentCompactIntVecBuilder::new(meta.n, &col_path(dir, meta.n_cols))?;
-        for slot in 0..meta.n { b.set(slot, value_of(slot)); }
+        for slot in 0..meta.n {
+            b.set(slot, value_of(slot));
+        }
         b.close()?;
         meta.n_cols += 1;
         meta.save(dir)
@@ -99,19 +137,19 @@ impl ColumnarCompactIntMatrix {
 
 // ── PackedCompactIntMatrix ────────────────────────────────────────────────────
 
-const PCMX_MAGIC:  [u8; 4] = *b"PCMX";
-const PCMX_HEADER: usize   = 24; // magic(4) + pad(4) + n_rows(8) + n_cols(8)
+const PCMX_MAGIC: [u8; 4] = *b"PCMX";
+const PCMX_HEADER: usize = 24; // magic(4) + pad(4) + n_rows(8) + n_cols(8)
 
 struct ColInfo {
     primary_start: usize,
-    data_offset:   usize,
-    n_overflow:    usize,
+    data_offset: usize,
+    n_overflow: usize,
 }
 
 pub struct PackedCompactIntMatrix {
-    mmap:    Mmap,
-    n_rows:  usize,
-    n_cols:  usize,
+    mmap: Mmap,
+    n_rows: usize,
+    n_cols: usize,
     columns: Vec<ColInfo>,
 }
 
@@ -119,43 +157,65 @@ impl PackedCompactIntMatrix {
     pub(crate) fn open(path: &Path) -> io::Result<Self> {
         let mmap = unsafe { Mmap::map(&File::open(path)?)? };
         if mmap.len() < PCMX_HEADER {
-            return Err(io::Error::new(io::ErrorKind::InvalidData, "PCMX file too short"));
+            return Err(io::Error::new(
+                io::ErrorKind::InvalidData,
+                "PCMX file too short",
+            ));
         }
         if &mmap[0..4] != &PCMX_MAGIC {
             return Err(io::Error::new(io::ErrorKind::InvalidData, "bad PCMX magic"));
         }
-        let n_rows = u64::from_le_bytes(mmap[8..16].try_into().unwrap())  as usize;
+        let n_rows = u64::from_le_bytes(mmap[8..16].try_into().unwrap()) as usize;
         let n_cols = u64::from_le_bytes(mmap[16..24].try_into().unwrap()) as usize;
 
         let mut columns = Vec::with_capacity(n_cols);
         for c in 0..n_cols {
-            let off_pos  = PCMX_HEADER + c * 8;
-            let col_base = u64::from_le_bytes(mmap[off_pos..off_pos+8].try_into().unwrap()) as usize;
-            let n_ov   = u64::from_le_bytes(mmap[col_base+16..col_base+24].try_into().unwrap()) as usize;
-            let n_pciv = u64::from_le_bytes(mmap[col_base+8..col_base+16].try_into().unwrap())  as usize;
+            let off_pos = PCMX_HEADER + c * 8;
+            let col_base =
+                u64::from_le_bytes(mmap[off_pos..off_pos + 8].try_into().unwrap()) as usize;
+            let n_ov =
+                u64::from_le_bytes(mmap[col_base + 16..col_base + 24].try_into().unwrap()) as usize;
+            let n_pciv =
+                u64::from_le_bytes(mmap[col_base + 8..col_base + 16].try_into().unwrap()) as usize;
             let primary_start = col_base + HEADER_SIZE;
-            let data_offset   = primary_start + n_pciv;
-            columns.push(ColInfo { primary_start, data_offset, n_overflow: n_ov });
+            let data_offset = primary_start + n_pciv;
+            columns.push(ColInfo {
+                primary_start,
+                data_offset,
+                n_overflow: n_ov,
+            });
         }
-        Ok(Self { mmap, n_rows, n_cols, columns })
+        Ok(Self {
+            mmap,
+            n_rows,
+            n_cols,
+            columns,
+        })
     }
 
     #[inline]
     pub(crate) fn col_view(&self, c: usize) -> IntSliceView<'_> {
         let ci = &self.columns[c];
-        let primary     = &self.mmap[ci.primary_start..ci.primary_start + self.n_rows];
-        let overflow_raw = &self.mmap[ci.data_offset..ci.data_offset + ci.n_overflow * OVERFLOW_ENTRY_SIZE];
+        let primary = &self.mmap[ci.primary_start..ci.primary_start + self.n_rows];
+        let overflow_raw =
+            &self.mmap[ci.data_offset..ci.data_offset + ci.n_overflow * OVERFLOW_ENTRY_SIZE];
         IntSliceView::new(primary, overflow_raw, ci.n_overflow, self.n_rows)
     }
 
-    pub(crate) fn col_persist(&self, c: usize, path: &Path) -> io::Result<PersistentCompactIntVecBuilder> {
+    pub(crate) fn col_persist(
+        &self,
+        c: usize,
+        path: &Path,
+    ) -> io::Result<PersistentCompactIntVecBuilder> {
         let view = self.col_view(c);
         let overflow: std::collections::HashMap<usize, u32> = view.overflow_entries().collect();
         PersistentCompactIntVecBuilder::from_raw_primary(view.primary_bytes(), overflow, path)
     }
 
     #[inline]
-    pub(crate) fn get(&self, col: usize, slot: usize) -> u32 { self.col_view(col).get(slot) }
+    pub(crate) fn get(&self, col: usize, slot: usize) -> u32 {
+        self.col_view(col).get(slot)
+    }
 
     #[inline]
     pub(crate) fn fill_row(&self, slot: usize, buf: &mut [u32]) {
@@ -180,27 +240,55 @@ impl PackedCompactIntMatrix {
     // via `PersistentCompactIntVec`. No formula is re-derived here.
 
     pub(crate) fn partial_bray_dist_matrix(&self) -> Array2<u64> {
-        pairwise_matrix(self.n_cols, |i, j| self.col_view(i).partial_bray_dist(self.col_view(j)))
+        pairwise_matrix(self.n_cols, |i, j| {
+            self.col_view(i).partial_bray_dist(self.col_view(j))
+        })
     }
     pub(crate) fn partial_euclidean_dist_matrix(&self) -> Array2<f64> {
-        pairwise_matrix(self.n_cols, |i, j| self.col_view(i).partial_euclidean_dist(self.col_view(j)))
+        pairwise_matrix(self.n_cols, |i, j| {
+            self.col_view(i).partial_euclidean_dist(self.col_view(j))
+        })
     }
-    pub(crate) fn partial_threshold_jaccard_dist_matrix(&self, t: u32) -> (Array2<u64>, Array2<u64>) {
-        pairwise2_matrix(self.n_cols, |i, j| self.col_view(i).partial_threshold_jaccard_dist(self.col_view(j), t))
+    pub(crate) fn partial_threshold_jaccard_dist_matrix(
+        &self,
+        t: u32,
+    ) -> (Array2<u64>, Array2<u64>) {
+        pairwise2_matrix(self.n_cols, |i, j| {
+            self.col_view(i)
+                .partial_threshold_jaccard_dist(self.col_view(j), t)
+        })
     }
     pub(crate) fn partial_relfreq_bray_dist_matrix(&self, col_sums: &Array1<u64>) -> Array2<f64> {
         pairwise_matrix(self.n_cols, |i, j| {
-            self.col_view(i).partial_relfreq_bray_dist(self.col_view(j), col_sums[i] as f64, col_sums[j] as f64)
+            self.col_view(i).partial_relfreq_bray_dist(
+                self.col_view(j),
+                col_sums[i] as f64,
+                col_sums[j] as f64,
+            )
         })
     }
-    pub(crate) fn partial_relfreq_euclidean_dist_matrix(&self, col_sums: &Array1<u64>) -> Array2<f64> {
+    pub(crate) fn partial_relfreq_euclidean_dist_matrix(
+        &self,
+        col_sums: &Array1<u64>,
+    ) -> Array2<f64> {
         pairwise_matrix(self.n_cols, |i, j| {
-            self.col_view(i).partial_relfreq_euclidean_dist(self.col_view(j), col_sums[i] as f64, col_sums[j] as f64)
+            self.col_view(i).partial_relfreq_euclidean_dist(
+                self.col_view(j),
+                col_sums[i] as f64,
+                col_sums[j] as f64,
+            )
         })
     }
-    pub(crate) fn partial_hellinger_euclidean_dist_matrix(&self, col_sums: &Array1<u64>) -> Array2<f64> {
+    pub(crate) fn partial_hellinger_euclidean_dist_matrix(
+        &self,
+        col_sums: &Array1<u64>,
+    ) -> Array2<f64> {
         pairwise_matrix(self.n_cols, |i, j| {
-            self.col_view(i).partial_hellinger_euclidean_dist(self.col_view(j), col_sums[i] as f64, col_sums[j] as f64)
+            self.col_view(i).partial_hellinger_euclidean_dist(
+                self.col_view(j),
+                col_sums[i] as f64,
+                col_sums[j] as f64,
+            )
         })
     }
 }
@@ -238,7 +326,9 @@ pub fn pack_compact_int_matrix(dir: &Path) -> io::Result<()> {
     // the columnar files are newer and must be (re-)packed, overwriting the
     // stale one — never silently discarded as "leftover cleanup".
     if packed_int_matrix_n_cols(&packed_path).ok() == Some(meta.n_cols) {
-        for c in 0..meta.n_cols { let _ = fs::remove_file(col_path(dir, c)); }
+        for c in 0..meta.n_cols {
+            let _ = fs::remove_file(col_path(dir, c));
+        }
         let _ = fs::remove_file(dir.join("meta.json"));
         return Ok(());
     }
@@ -250,32 +340,41 @@ pub fn pack_compact_int_matrix(dir: &Path) -> io::Result<()> {
     let header_size = (PCMX_HEADER + n_cols * 8) as u64;
     let mut col_offset = header_size;
     let mut offsets = Vec::with_capacity(n_cols);
-    for &size in &col_sizes { offsets.push(col_offset); col_offset += size; }
+    for &size in &col_sizes {
+        offsets.push(col_offset);
+        col_offset += size;
+    }
     let tmp_path = dir.join("matrix.pcmx.tmp");
     let mut out = BufWriter::new(File::create(&tmp_path)?);
     out.write_all(&PCMX_MAGIC)?;
     out.write_all(&[0u8; 4])?;
     out.write_all(&(meta.n as u64).to_le_bytes())?;
     out.write_all(&(n_cols as u64).to_le_bytes())?;
-    for &off in &offsets { out.write_all(&off.to_le_bytes())?; }
-    for c in 0..n_cols { io::copy(&mut File::open(col_path(dir, c))?, &mut out)?; }
+    for &off in &offsets {
+        out.write_all(&off.to_le_bytes())?;
+    }
+    for c in 0..n_cols {
+        io::copy(&mut File::open(col_path(dir, c))?, &mut out)?;
+    }
     out.flush()?;
     drop(out);
     fs::rename(&tmp_path, &packed_path)?;
-    for c in 0..n_cols { fs::remove_file(col_path(dir, c))?; }
+    for c in 0..n_cols {
+        fs::remove_file(col_path(dir, c))?;
+    }
     fs::remove_file(dir.join("meta.json"))?;
     Ok(())
 }
 
 // ── PersistentCompactIntMatrix — public enum ──────────────────────────────────
 
-pub enum PersistentCompactIntMatrix {
+pub enum PersistentIntMatrix {
     Columnar(ColumnarCompactIntMatrix),
     Packed(PackedCompactIntMatrix),
     Sparse(PersistentSparseCompactIntMatrix),
 }
 
-impl PersistentCompactIntMatrix {
+impl PersistentIntMatrix {
     /// Checks (in order): `counts/matrix.pcmx` → Packed; `counts/meta.json`
     /// → Columnar; `counts/singleton_values.pciv` → Sparse. Mirrors
     /// `PersistentBitMatrix::open`'s own Packed → Columnar → Sparse
@@ -283,17 +382,24 @@ impl PersistentCompactIntMatrix {
     pub fn open(layer_dir: &Path) -> io::Result<Self> {
         let counts_dir = layer_dir.join("counts");
         if counts_dir.join("matrix.pcmx").exists() {
-            return Ok(Self::Packed(PackedCompactIntMatrix::open(&counts_dir.join("matrix.pcmx"))?));
+            return Ok(Self::Packed(PackedCompactIntMatrix::open(
+                &counts_dir.join("matrix.pcmx"),
+            )?));
         }
         if MatrixMeta::load(&counts_dir).is_ok() {
             return Ok(Self::Columnar(ColumnarCompactIntMatrix::open(&counts_dir)?));
         }
         if sparse_is_present(&counts_dir) {
-            return Ok(Self::Sparse(PersistentSparseCompactIntMatrix::open(&counts_dir)?));
+            return Ok(Self::Sparse(PersistentSparseCompactIntMatrix::open(
+                &counts_dir,
+            )?));
         }
         Err(io::Error::new(
             io::ErrorKind::NotFound,
-            format!("no count matrix found in {} — run 'obikmer upgrade'", layer_dir.display()),
+            format!(
+                "no count matrix found in {} — run 'obikmer upgrade'",
+                layer_dir.display()
+            ),
         ))
     }
 
@@ -303,8 +409,8 @@ impl PersistentCompactIntMatrix {
     pub fn storage_kind(&self) -> StorageKind {
         match self {
             Self::Columnar(_) => StorageKind::Columnar,
-            Self::Packed(_)   => StorageKind::Packed,
-            Self::Sparse(_)   => StorageKind::Sparse,
+            Self::Packed(_) => StorageKind::Packed,
+            Self::Sparse(_) => StorageKind::Sparse,
         }
     }
 
@@ -330,11 +436,19 @@ impl PersistentCompactIntMatrix {
 
     #[inline]
     pub fn n(&self) -> usize {
-        match self { Self::Columnar(m) => m.n(), Self::Packed(m) => m.n_rows, Self::Sparse(m) => m.n() }
+        match self {
+            Self::Columnar(m) => m.n(),
+            Self::Packed(m) => m.n_rows,
+            Self::Sparse(m) => m.n(),
+        }
     }
     #[inline]
     pub fn n_cols(&self) -> usize {
-        match self { Self::Columnar(m) => m.n_cols(), Self::Packed(m) => m.n_cols, Self::Sparse(m) => m.n_cols() }
+        match self {
+            Self::Columnar(m) => m.n_cols(),
+            Self::Packed(m) => m.n_cols,
+            Self::Sparse(m) => m.n_cols(),
+        }
     }
 
     #[inline]
@@ -349,30 +463,38 @@ impl PersistentCompactIntMatrix {
     pub fn col_view(&self, c: usize) -> IntSliceView<'_> {
         match self {
             Self::Columnar(m) => m.col(c).view(),
-            Self::Packed(m)   => m.col_view(c),
-            Self::Sparse(_)   => panic!("col_view() not available on Sparse PersistentCompactIntMatrix"),
+            Self::Packed(m) => m.col_view(c),
+            Self::Sparse(_) => {
+                panic!("col_view() not available on Sparse PersistentCompactIntMatrix")
+            }
         }
     }
 
     pub fn col_persist(&self, c: usize, path: &Path) -> io::Result<PersistentCompactIntVecBuilder> {
         match self {
             Self::Columnar(m) => PersistentCompactIntVecBuilder::build_from(m.col(c), path),
-            Self::Packed(m)   => m.col_persist(c, path),
-            Self::Sparse(_)   => Err(io::Error::new(io::ErrorKind::Unsupported,
-                "col_persist not available on Sparse PersistentCompactIntMatrix")),
+            Self::Packed(m) => m.col_persist(c, path),
+            Self::Sparse(_) => Err(io::Error::new(
+                io::ErrorKind::Unsupported,
+                "col_persist not available on Sparse PersistentCompactIntMatrix",
+            )),
         }
     }
 
     #[inline]
     pub fn row(&self, slot: usize) -> Box<[u32]> {
-        match self { Self::Columnar(m) => m.row(slot), Self::Packed(m) => m.row(slot), Self::Sparse(m) => m.row(slot) }
+        match self {
+            Self::Columnar(m) => m.row(slot),
+            Self::Packed(m) => m.row(slot),
+            Self::Sparse(m) => m.row(slot),
+        }
     }
     #[inline]
     pub fn fill_row(&self, slot: usize, buf: &mut [u32]) {
         match self {
             Self::Columnar(m) => m.fill_row(slot, buf),
-            Self::Packed(m)   => m.fill_row(slot, buf),
-            Self::Sparse(m)   => m.fill_row(slot, buf),
+            Self::Packed(m) => m.fill_row(slot, buf),
+            Self::Sparse(m) => m.fill_row(slot, buf),
         }
     }
 
@@ -418,73 +540,86 @@ impl PersistentCompactIntMatrix {
     /// `Columnar`/`Packed` reuse the shared sorted-slot batching in
     /// `views::nonzero_triples`. Boxed, not `impl Iterator`, because the
     /// match arms are genuinely different concrete types.
-    pub fn nonzero_iter<'a>(&'a self, slots: &'a [usize]) -> Box<dyn Iterator<Item = (usize, usize, u32)> + 'a> {
+    pub fn nonzero_iter<'a>(
+        &'a self,
+        slots: &'a [usize],
+    ) -> Box<dyn Iterator<Item = (usize, usize, u32)> + 'a> {
         match self {
             Self::Sparse(m) => Box::new(m.nonzero_iter(slots)),
-            Self::Columnar(_) | Self::Packed(_) => {
-                Box::new(nonzero_triples(slots, self.n_cols(), |c| self.col_view(c), false))
-            }
+            Self::Columnar(_) | Self::Packed(_) => Box::new(nonzero_triples(
+                slots,
+                self.n_cols(),
+                |c| self.col_view(c),
+                false,
+            )),
         }
     }
 
     #[inline]
     pub fn sum(&self) -> Array1<u64> {
-        match self { Self::Columnar(m) => m.sum(), Self::Packed(m) => m.sum(), Self::Sparse(m) => m.sum() }
+        match self {
+            Self::Columnar(m) => m.sum(),
+            Self::Packed(m) => m.sum(),
+            Self::Sparse(m) => m.sum(),
+        }
     }
     #[inline]
     pub fn count_nonzero(&self) -> Array1<u64> {
         match self {
             Self::Columnar(m) => m.count_nonzero(),
-            Self::Packed(m)   => m.count_nonzero(),
-            Self::Sparse(m)   => m.count_nonzero(),
+            Self::Packed(m) => m.count_nonzero(),
+            Self::Sparse(m) => m.count_nonzero(),
         }
     }
     #[inline]
     pub fn partial_bray_dist_matrix(&self) -> Array2<u64> {
         match self {
             Self::Columnar(m) => m.partial_bray_dist_matrix(),
-            Self::Packed(m)   => m.partial_bray_dist_matrix(),
-            Self::Sparse(m)   => CountPartials::partial_bray(m),
+            Self::Packed(m) => m.partial_bray_dist_matrix(),
+            Self::Sparse(m) => CountPartials::partial_bray(m),
         }
     }
     #[inline]
     pub fn partial_euclidean_dist_matrix(&self) -> Array2<f64> {
         match self {
             Self::Columnar(m) => m.partial_euclidean_dist_matrix(),
-            Self::Packed(m)   => m.partial_euclidean_dist_matrix(),
-            Self::Sparse(m)   => CountPartials::partial_euclidean(m),
+            Self::Packed(m) => m.partial_euclidean_dist_matrix(),
+            Self::Sparse(m) => CountPartials::partial_euclidean(m),
         }
     }
     #[inline]
-    pub fn partial_threshold_jaccard_dist_matrix(&self, threshold: u32) -> (Array2<u64>, Array2<u64>) {
+    pub fn partial_threshold_jaccard_dist_matrix(
+        &self,
+        threshold: u32,
+    ) -> (Array2<u64>, Array2<u64>) {
         match self {
             Self::Columnar(m) => m.partial_threshold_jaccard_dist_matrix(threshold),
-            Self::Packed(m)   => m.partial_threshold_jaccard_dist_matrix(threshold),
-            Self::Sparse(m)   => CountPartials::partial_threshold_jaccard(m, threshold),
+            Self::Packed(m) => m.partial_threshold_jaccard_dist_matrix(threshold),
+            Self::Sparse(m) => CountPartials::partial_threshold_jaccard(m, threshold),
         }
     }
     #[inline]
     pub fn partial_relfreq_bray_dist_matrix(&self, col_sums: &Array1<u64>) -> Array2<f64> {
         match self {
             Self::Columnar(m) => m.partial_relfreq_bray_dist_matrix(col_sums),
-            Self::Packed(m)   => m.partial_relfreq_bray_dist_matrix(col_sums),
-            Self::Sparse(m)   => CountPartials::partial_relfreq_bray(m, col_sums),
+            Self::Packed(m) => m.partial_relfreq_bray_dist_matrix(col_sums),
+            Self::Sparse(m) => CountPartials::partial_relfreq_bray(m, col_sums),
         }
     }
     #[inline]
     pub fn partial_relfreq_euclidean_dist_matrix(&self, col_sums: &Array1<u64>) -> Array2<f64> {
         match self {
             Self::Columnar(m) => m.partial_relfreq_euclidean_dist_matrix(col_sums),
-            Self::Packed(m)   => m.partial_relfreq_euclidean_dist_matrix(col_sums),
-            Self::Sparse(m)   => CountPartials::partial_relfreq_euclidean(m, col_sums),
+            Self::Packed(m) => m.partial_relfreq_euclidean_dist_matrix(col_sums),
+            Self::Sparse(m) => CountPartials::partial_relfreq_euclidean(m, col_sums),
         }
     }
     #[inline]
     pub fn partial_hellinger_euclidean_dist_matrix(&self, col_sums: &Array1<u64>) -> Array2<f64> {
         match self {
             Self::Columnar(m) => m.partial_hellinger_euclidean_dist_matrix(col_sums),
-            Self::Packed(m)   => m.partial_hellinger_euclidean_dist_matrix(col_sums),
-            Self::Sparse(m)   => CountPartials::partial_hellinger(m, col_sums),
+            Self::Packed(m) => m.partial_hellinger_euclidean_dist_matrix(col_sums),
+            Self::Sparse(m) => CountPartials::partial_hellinger(m, col_sums),
         }
     }
     #[inline]
@@ -497,40 +632,60 @@ impl PersistentCompactIntMatrix {
 
 use crate::traits::{ColumnWeights, CountPartials};
 
-impl ColumnWeights for PersistentCompactIntMatrix {
+impl ColumnWeights for PersistentIntMatrix {
     #[inline]
-    fn col_weights(&self) -> Array1<u64> { self.sum() }
+    fn col_weights(&self) -> Array1<u64> {
+        self.sum()
+    }
     #[inline]
-    fn partial_kmer_counts(&self) -> Array1<u64> { self.count_nonzero() }
+    fn partial_kmer_counts(&self) -> Array1<u64> {
+        self.count_nonzero()
+    }
 }
 
-impl CountPartials for PersistentCompactIntMatrix {
+impl CountPartials for PersistentIntMatrix {
     #[inline]
-    fn partial_bray(&self) -> Array2<u64>                                 { self.partial_bray_dist_matrix() }
+    fn partial_bray(&self) -> Array2<u64> {
+        self.partial_bray_dist_matrix()
+    }
     #[inline]
-    fn partial_euclidean(&self) -> Array2<f64>                            { self.partial_euclidean_dist_matrix() }
+    fn partial_euclidean(&self) -> Array2<f64> {
+        self.partial_euclidean_dist_matrix()
+    }
     #[inline]
-    fn partial_threshold_jaccard(&self, t: u32) -> (Array2<u64>, Array2<u64>) { self.partial_threshold_jaccard_dist_matrix(t) }
+    fn partial_threshold_jaccard(&self, t: u32) -> (Array2<u64>, Array2<u64>) {
+        self.partial_threshold_jaccard_dist_matrix(t)
+    }
     #[inline]
-    fn partial_relfreq_bray(&self, g: &Array1<u64>) -> Array2<f64>        { self.partial_relfreq_bray_dist_matrix(g) }
+    fn partial_relfreq_bray(&self, g: &Array1<u64>) -> Array2<f64> {
+        self.partial_relfreq_bray_dist_matrix(g)
+    }
     #[inline]
-    fn partial_relfreq_euclidean(&self, g: &Array1<u64>) -> Array2<f64>   { self.partial_relfreq_euclidean_dist_matrix(g) }
+    fn partial_relfreq_euclidean(&self, g: &Array1<u64>) -> Array2<f64> {
+        self.partial_relfreq_euclidean_dist_matrix(g)
+    }
     #[inline]
-    fn partial_hellinger(&self, g: &Array1<u64>) -> Array2<f64>           { self.partial_hellinger_euclidean_dist_matrix(g) }
+    fn partial_hellinger(&self, g: &Array1<u64>) -> Array2<f64> {
+        self.partial_hellinger_euclidean_dist_matrix(g)
+    }
 }
 
 // ── Builder ───────────────────────────────────────────────────────────────────
 
 pub struct PersistentCompactIntMatrixBuilder {
-    dir:    PathBuf,
-    n:      usize,
+    dir: PathBuf,
+    n: usize,
     n_cols: usize,
 }
 
 impl PersistentCompactIntMatrixBuilder {
     pub fn new(n: usize, dir: &Path) -> io::Result<Self> {
         fs::create_dir_all(dir)?;
-        Ok(Self { dir: dir.to_path_buf(), n, n_cols: 0 })
+        Ok(Self {
+            dir: dir.to_path_buf(),
+            n,
+            n_cols: 0,
+        })
     }
 
     /// Resume appending columns to a Columnar matrix directory already
@@ -541,13 +696,21 @@ impl PersistentCompactIntMatrixBuilder {
     /// on-disk column naming or `MatrixMeta` themselves.
     pub fn resume(dir: &Path) -> io::Result<Self> {
         let meta = MatrixMeta::load(dir)?;
-        Ok(Self { dir: dir.to_path_buf(), n: meta.n, n_cols: meta.n_cols })
+        Ok(Self {
+            dir: dir.to_path_buf(),
+            n: meta.n,
+            n_cols: meta.n_cols,
+        })
     }
 
     #[inline]
-    pub fn n(&self)      -> usize { self.n }
+    pub fn n(&self) -> usize {
+        self.n
+    }
     #[inline]
-    pub fn n_cols(&self) -> usize { self.n_cols }
+    pub fn n_cols(&self) -> usize {
+        self.n_cols
+    }
     pub fn add_col(&mut self) -> io::Result<PersistentCompactIntVecBuilder> {
         let path = col_path(&self.dir, self.n_cols);
         self.n_cols += 1;
@@ -569,14 +732,22 @@ impl PersistentCompactIntMatrixBuilder {
     }
 
     pub fn close(self) -> io::Result<()> {
-        MatrixMeta { n: self.n, n_cols: self.n_cols }.save(&self.dir)
+        MatrixMeta {
+            n: self.n,
+            n_cols: self.n_cols,
+        }
+        .save(&self.dir)
     }
 }
 
 // ── MatrixGroupOps ────────────────────────────────────────────────────────────
 
-impl MatrixGroupOps for PersistentCompactIntMatrix {
-    fn partial_group_presence_count(&self, g: &ColGroup, threshold: u32) -> io::Result<TempCompactIntVec> {
+impl MatrixGroupOps for PersistentIntMatrix {
+    fn partial_group_presence_count(
+        &self,
+        g: &ColGroup,
+        threshold: u32,
+    ) -> io::Result<TempCompactIntVec> {
         chunked_presence_count(self.n(), &g.indices, |b, c| {
             b.inc_predicate_fast(self.col_view(c), |v| v >= threshold)
         })
@@ -585,7 +756,9 @@ impl MatrixGroupOps for PersistentCompactIntMatrix {
     fn partial_group_sum(&self, g: &ColGroup) -> io::Result<TempCompactIntVec> {
         let n = self.n();
         let mut result = TempCompactIntVecBuilder::new(n)?;
-        for &c in &g.indices { result.add(self.col_view(c)); }
+        for &c in &g.indices {
+            result.add(self.col_view(c));
+        }
         result.freeze()
     }
 
@@ -603,7 +776,9 @@ impl MatrixGroupOps for PersistentCompactIntMatrix {
         let mut result = TempCompactIntVecBuilder::new(n)?;
         if let Some((&first, rest)) = g.indices.split_first() {
             result.add(self.col_view(first));
-            for &c in rest { result.min(self.col_view(c)); }
+            for &c in rest {
+                result.min(self.col_view(c));
+            }
         }
         result.freeze()
     }
@@ -611,7 +786,9 @@ impl MatrixGroupOps for PersistentCompactIntMatrix {
     fn partial_group_max(&self, g: &ColGroup) -> io::Result<TempCompactIntVec> {
         let n = self.n();
         let mut result = TempCompactIntVecBuilder::new(n)?;
-        for &c in &g.indices { result.max(self.col_view(c)); }
+        for &c in &g.indices {
+            result.max(self.col_view(c));
+        }
         result.freeze()
     }
 }
diff --git a/src/obicompactvec/src/lib.rs b/src/obicompactvec/src/lib.rs
index bb7782b2..a965ff39 100644
--- a/src/obicompactvec/src/lib.rs
+++ b/src/obicompactvec/src/lib.rs
@@ -1,41 +1,50 @@
-mod bitvec;
 mod bitmatrix;
+mod bitvec;
 mod builder;
 mod colgroup;
 mod eliasfano;
 mod fixedintvec;
 mod format;
-mod rankselect;
 mod intmatrix;
 mod layer_meta;
 mod matrix_builder;
 mod meta;
 mod mmap_file;
+mod rankselect;
 mod reader;
 mod sparse_intmatrix;
 mod storage_kind;
 mod tempbitvec;
 mod tempintvec;
-mod views;
 pub mod traits;
+mod views;
 
+pub use bitmatrix::{
+    PersistentBitMatrix, PersistentBitMatrixBuilder, PersistentSparseBitMatrix,
+    PersistentSparseBitMatrixBuilder, pack_bit_matrix, pack_sparse_bit_matrix,
+};
 pub use bitvec::{BitIter, PersistentBitVec, PersistentBitVecBuilder};
-pub use fixedintvec::{PersistentFixedIntVec, PersistentFixedIntVecBuilder, bit_width_for_range};
-pub use rankselect::{PersistentRankSelectBitVec, PersistentRankSelectBitVecBuilder};
-pub use eliasfano::{EliasFano, EliasFanoBuilder};
-pub use bitmatrix::{PersistentBitMatrix, PersistentBitMatrixBuilder, PersistentSparseBitMatrix, PersistentSparseBitMatrixBuilder, pack_bit_matrix, pack_sparse_bit_matrix};
 pub use builder::PersistentCompactIntVecBuilder;
 pub use colgroup::{ColGroup, FilterMask, MatrixGroupOps, eval_filter_mask};
-pub use intmatrix::{PersistentCompactIntMatrix, PersistentCompactIntMatrixBuilder, pack_compact_int_matrix};
+pub use eliasfano::{EliasFano, EliasFanoBuilder};
+pub use fixedintvec::{PersistentFixedIntVec, PersistentFixedIntVecBuilder, bit_width_for_range};
+pub use intmatrix::{
+    PersistentCompactIntMatrixBuilder, PersistentIntMatrix, pack_compact_int_matrix,
+};
+
 pub use layer_meta::LayerMeta;
 pub use matrix_builder::{ColBuilder, MatrixBuilder};
-pub use reader::{PersistentCompactIntVec, Iter as CompactIntVecIter};
-pub use sparse_intmatrix::{PersistentSparseCompactIntMatrix, PersistentSparseCompactIntMatrixBuilder, pack_sparse_compact_int_matrix};
+pub use rankselect::{PersistentRankSelectBitVec, PersistentRankSelectBitVecBuilder};
+pub use reader::{Iter as CompactIntVecIter, PersistentCompactIntVec};
+pub use sparse_intmatrix::{
+    PersistentSparseCompactIntMatrix, PersistentSparseCompactIntMatrixBuilder,
+    pack_sparse_compact_int_matrix,
+};
 pub use storage_kind::StorageKind;
 pub use tempbitvec::{TempBitVec, TempBitVecBuilder};
 pub use tempintvec::{TempCompactIntVec, TempCompactIntVecBuilder};
 pub use traits::{BinaryMatrix, BitPartials, ColumnWeights, CountPartials};
-pub use views::{BitSliceView, BitSliceIter, IntSliceView, IntSliceViewIter};
+pub use views::{BitSliceIter, BitSliceView, IntSliceView, IntSliceViewIter};
 
 #[cfg(test)]
 #[path = "tests/mod.rs"]
diff --git a/src/obicompactvec/src/sparse_intmatrix.rs b/src/obicompactvec/src/sparse_intmatrix.rs
index 7f58d2c5..2d596f48 100644
--- a/src/obicompactvec/src/sparse_intmatrix.rs
+++ b/src/obicompactvec/src/sparse_intmatrix.rs
@@ -35,11 +35,17 @@ use crate::builder::PersistentCompactIntVecBuilder;
 use crate::eliasfano::{EliasFano, EliasFanoBuilder};
 use crate::reader::PersistentCompactIntVec;
 use crate::traits::{BitPartials, ColumnWeights, CountPartials};
-use crate::{PersistentCompactIntMatrix, PersistentSparseBitMatrix, PersistentSparseBitMatrixBuilder};
+use crate::{PersistentIntMatrix, PersistentSparseBitMatrix, PersistentSparseBitMatrixBuilder};
 
-fn singleton_values_path(dir: &Path) -> PathBuf { dir.join("singleton_values.pciv") }
-fn multi_values_path(dir: &Path) -> PathBuf { dir.join("multi_values.pciv") }
-fn multi_offsets_base(dir: &Path) -> PathBuf { dir.join("multi_offsets") }
+fn singleton_values_path(dir: &Path) -> PathBuf {
+    dir.join("singleton_values.pciv")
+}
+fn multi_values_path(dir: &Path) -> PathBuf {
+    dir.join("multi_values.pciv")
+}
+fn multi_offsets_base(dir: &Path) -> PathBuf {
+    dir.join("multi_offsets")
+}
 
 /// Lightweight disk probe: true iff a sparse count matrix has already been
 /// written at `dir` — the marker [`PersistentCompactIntMatrix::open`]/
@@ -73,9 +79,13 @@ impl PersistentSparseCompactIntMatrix {
     }
 
     #[inline]
-    pub fn n(&self) -> usize { self.support.n() }
+    pub fn n(&self) -> usize {
+        self.support.n()
+    }
     #[inline]
-    pub fn n_cols(&self) -> usize { self.support.n_cols() }
+    pub fn n_cols(&self) -> usize {
+        self.support.n_cols()
+    }
 
     /// Calls `f(col, value)` once per non-zero column at `slot`, in
     /// ascending column order — the shared decode branch behind every
@@ -104,7 +114,11 @@ impl PersistentSparseCompactIntMatrix {
     /// absent).
     pub fn get(&self, c: usize, slot: usize) -> u32 {
         let mut found = 0u32;
-        self.for_each_cell_in_row(slot, |g, v| if g == c { found = v; });
+        self.for_each_cell_in_row(slot, |g, v| {
+            if g == c {
+                found = v;
+            }
+        });
         found
     }
 
@@ -138,27 +152,32 @@ impl PersistentSparseCompactIntMatrix {
     /// Yields every `(idx into slots, col, value)` triple, row by row, in
     /// `slots` order — mirrors
     /// [`PersistentSparseBitMatrix::nonzero_iter`].
-    pub fn nonzero_iter<'a>(&'a self, slots: &'a [usize]) -> impl Iterator<Item = (usize, usize, u32)> + 'a {
+    pub fn nonzero_iter<'a>(
+        &'a self,
+        slots: &'a [usize],
+    ) -> impl Iterator<Item = (usize, usize, u32)> + 'a {
         let mut next_slot = 0usize;
         let mut cur_idx = 0usize;
         let mut buf: Vec<(usize, u32)> = Vec::new();
         let mut buf_pos = 0usize;
 
-        std::iter::from_fn(move || loop {
-            if buf_pos < buf.len() {
-                let (g, v) = buf[buf_pos];
-                buf_pos += 1;
-                return Some((cur_idx, g, v));
+        std::iter::from_fn(move || {
+            loop {
+                if buf_pos < buf.len() {
+                    let (g, v) = buf[buf_pos];
+                    buf_pos += 1;
+                    return Some((cur_idx, g, v));
+                }
+                if next_slot >= slots.len() {
+                    return None;
+                }
+                cur_idx = next_slot;
+                let slot = slots[next_slot];
+                next_slot += 1;
+                buf.clear();
+                self.for_each_cell_in_row(slot, |g, v| buf.push((g, v)));
+                buf_pos = 0;
             }
-            if next_slot >= slots.len() {
-                return None;
-            }
-            cur_idx = next_slot;
-            let slot = slots[next_slot];
-            next_slot += 1;
-            buf.clear();
-            self.for_each_cell_in_row(slot, |g, v| buf.push((g, v)));
-            buf_pos = 0;
         })
     }
 
@@ -203,7 +222,11 @@ impl PersistentSparseCompactIntMatrix {
     fn count_geq(&self, threshold: u32) -> Array1<u64> {
         let mut counts = vec![0u64; self.n_cols()];
         for slot in 0..self.n() {
-            self.for_each_cell_in_row(slot, |g, v| if v >= threshold { counts[g] += 1; });
+            self.for_each_cell_in_row(slot, |g, v| {
+                if v >= threshold {
+                    counts[g] += 1;
+                }
+            });
         }
         Array1::from(counts)
     }
@@ -261,9 +284,13 @@ impl PersistentSparseCompactIntMatrix {
 
 impl ColumnWeights for PersistentSparseCompactIntMatrix {
     #[inline]
-    fn col_weights(&self) -> Array1<u64> { self.sum() }
+    fn col_weights(&self) -> Array1<u64> {
+        self.sum()
+    }
     #[inline]
-    fn partial_kmer_counts(&self) -> Array1<u64> { self.count_nonzero() }
+    fn partial_kmer_counts(&self) -> Array1<u64> {
+        self.count_nonzero()
+    }
 }
 
 impl CountPartials for PersistentSparseCompactIntMatrix {
@@ -278,7 +305,9 @@ impl CountPartials for PersistentSparseCompactIntMatrix {
     fn partial_bray(&self) -> Array2<u64> {
         let mut m = self.row_major_pairwise(|_, a, _, b| (a as u64).min(b as u64));
         let sum = self.sum();
-        for i in 0..self.n_cols() { m[[i, i]] = sum[i]; }
+        for i in 0..self.n_cols() {
+            m[[i, i]] = sum[i];
+        }
         m
     }
 
@@ -329,7 +358,8 @@ impl CountPartials for PersistentSparseCompactIntMatrix {
             // left to patch.
             return BitPartials::partial_jaccard(&self.support);
         }
-        let mut inter = self.row_major_pairwise(|_, a, _, b| (a >= threshold && b >= threshold) as u64);
+        let mut inter =
+            self.row_major_pairwise(|_, a, _, b| (a >= threshold && b >= threshold) as u64);
         let mut union = Array2::<u64>::zeros((n, n));
         for i in 0..n {
             for j in 0..n {
@@ -363,7 +393,11 @@ impl CountPartials for PersistentSparseCompactIntMatrix {
         });
         let sum = self.sum();
         for i in 0..self.n_cols() {
-            m[[i, i]] = if global[i] > 0 { sum[i] as f64 / global[i] as f64 } else { 0.0 };
+            m[[i, i]] = if global[i] > 0 {
+                sum[i] as f64 / global[i] as f64
+            } else {
+                0.0
+            };
         }
         m
     }
@@ -382,9 +416,21 @@ impl CountPartials for PersistentSparseCompactIntMatrix {
                 if i != j {
                     let sa = global[i] as f64;
                     let sb = global[j] as f64;
-                    let sq_a = if sa > 0.0 { sq[i] as f64 / (sa * sa) } else { 0.0 };
-                    let sq_b = if sb > 0.0 { sq[j] as f64 / (sb * sb) } else { 0.0 };
-                    let cross = if sa > 0.0 && sb > 0.0 { dot[[i, j]] / (sa * sb) } else { 0.0 };
+                    let sq_a = if sa > 0.0 {
+                        sq[i] as f64 / (sa * sa)
+                    } else {
+                        0.0
+                    };
+                    let sq_b = if sb > 0.0 {
+                        sq[j] as f64 / (sb * sb)
+                    } else {
+                        0.0
+                    };
+                    let cross = if sa > 0.0 && sb > 0.0 {
+                        dot[[i, j]] / (sa * sb)
+                    } else {
+                        0.0
+                    };
                     m[[i, j]] = sq_a + sq_b - 2.0 * cross;
                 }
             }
@@ -409,7 +455,11 @@ impl CountPartials for PersistentSparseCompactIntMatrix {
                     let sb = global[j] as f64;
                     let pa_sum = if sa > 0.0 { sum[i] as f64 / sa } else { 0.0 };
                     let pb_sum = if sb > 0.0 { sum[j] as f64 / sb } else { 0.0 };
-                    let cross = if sa > 0.0 && sb > 0.0 { sqrt_dot[[i, j]] / (sa * sb).sqrt() } else { 0.0 };
+                    let cross = if sa > 0.0 && sb > 0.0 {
+                        sqrt_dot[[i, j]] / (sa * sb).sqrt()
+                    } else {
+                        0.0
+                    };
                     m[[i, j]] = pa_sum + pb_sum - 2.0 * cross;
                 }
             }
@@ -461,7 +511,6 @@ impl PersistentSparseCompactIntMatrixBuilder {
         self.support.push_row(cols);
     }
 
-
     /// Builds a sparse matrix from an already-built dense
     /// [`PersistentCompactIntMatrix`] (`Columnar` or `Packed`) — same
     /// batched-transpose shape as
@@ -475,7 +524,7 @@ impl PersistentSparseCompactIntMatrixBuilder {
     /// pairs are appended to its own buffer in strictly ascending column
     /// order "for free", matching `push_row`'s ascending-`cols` contract
     /// without an explicit sort.
-    pub fn build_from_dense(dense: &PersistentCompactIntMatrix, dir: &Path) -> io::Result<Self> {
+    pub fn build_from_dense(dense: &PersistentIntMatrix, dir: &Path) -> io::Result<Self> {
         let n = dense.n();
         let n_cols = dense.n_cols();
         let mut builder = Self::new(n, n_cols, dir)?;
@@ -500,23 +549,34 @@ impl PersistentSparseCompactIntMatrixBuilder {
     }
 
     pub fn close(self) -> io::Result<()> {
-        let Self { support, dir, singleton_values, multi_values, multi_row_offsets } = self;
+        let Self {
+            support,
+            dir,
+            singleton_values,
+            multi_values,
+            multi_row_offsets,
+        } = self;
         support.close()?;
 
-        let mut sv = PersistentCompactIntVecBuilder::new(singleton_values.len(), &singleton_values_path(&dir))?;
+        let mut sv = PersistentCompactIntVecBuilder::new(
+            singleton_values.len(),
+            &singleton_values_path(&dir),
+        )?;
         for (i, &v) in singleton_values.iter().enumerate() {
             sv.set(i, v);
         }
         sv.close()?;
 
-        let mut mv = PersistentCompactIntVecBuilder::new(multi_values.len(), &multi_values_path(&dir))?;
+        let mut mv =
+            PersistentCompactIntVecBuilder::new(multi_values.len(), &multi_values_path(&dir))?;
         for (i, &v) in multi_values.iter().enumerate() {
             mv.set(i, v);
         }
         mv.close()?;
 
         let universe = multi_values.len() as u64 + 1;
-        let mut mo = EliasFanoBuilder::new(multi_row_offsets.len(), universe, &multi_offsets_base(&dir))?;
+        let mut mo =
+            EliasFanoBuilder::new(multi_row_offsets.len(), universe, &multi_offsets_base(&dir))?;
         for &o in &multi_row_offsets {
             mo.push(o);
         }
@@ -544,7 +604,7 @@ impl PersistentSparseCompactIntMatrixBuilder {
 /// half-written one). Idempotent — a no-op if `singleton_values.pciv`
 /// already exists.
 pub fn pack_sparse_compact_int_matrix(dir: &Path) -> io::Result<()> {
-    use crate::intmatrix::{col_path, ColumnarCompactIntMatrix, PackedCompactIntMatrix};
+    use crate::intmatrix::{ColumnarCompactIntMatrix, PackedCompactIntMatrix, col_path};
 
     if is_present(dir) {
         return Ok(());
@@ -552,12 +612,12 @@ pub fn pack_sparse_compact_int_matrix(dir: &Path) -> io::Result<()> {
 
     let packed_path = dir.join("matrix.pcmx");
     if packed_path.exists() {
-        let dense = PersistentCompactIntMatrix::Packed(PackedCompactIntMatrix::open(&packed_path)?);
+        let dense = PersistentIntMatrix::Packed(PackedCompactIntMatrix::open(&packed_path)?);
         PersistentSparseCompactIntMatrixBuilder::build_from_dense(&dense, dir)?.close()?;
         drop(dense);
         fs::remove_file(&packed_path)?;
     } else {
-        let dense = PersistentCompactIntMatrix::Columnar(ColumnarCompactIntMatrix::open(dir)?);
+        let dense = PersistentIntMatrix::Columnar(ColumnarCompactIntMatrix::open(dir)?);
         let n_cols = dense.n_cols();
         PersistentSparseCompactIntMatrixBuilder::build_from_dense(&dense, dir)?.close()?;
         drop(dense);
diff --git a/src/obicompactvec/src/tests/colgroup.rs b/src/obicompactvec/src/tests/colgroup.rs
index d1c7cf1f..b11ba39f 100644
--- a/src/obicompactvec/src/tests/colgroup.rs
+++ b/src/obicompactvec/src/tests/colgroup.rs
@@ -1,25 +1,26 @@
 use tempfile::tempdir;
 
 use crate::{
-    ColGroup, MatrixGroupOps,
-    PersistentBitMatrix, PersistentBitMatrixBuilder,
-    PersistentCompactIntMatrix, PersistentCompactIntMatrixBuilder,
+    ColGroup, MatrixGroupOps, PersistentBitMatrix, PersistentBitMatrixBuilder,
+    PersistentIntMatrix, PersistentCompactIntMatrixBuilder,
 };
 use crate::{PersistentBitVecBuilder, PersistentCompactIntVec, PersistentCompactIntVecBuilder};
 
 // ── helpers ───────────────────────────────────────────────────────────────────
 
-fn make_int_matrix(cols: &[&[u32]]) -> (tempfile::TempDir, PersistentCompactIntMatrix) {
+fn make_int_matrix(cols: &[&[u32]]) -> (tempfile::TempDir, PersistentIntMatrix) {
     let n = cols.first().map_or(0, |c| c.len());
     let dir = tempdir().unwrap();
     let mut b = PersistentCompactIntMatrixBuilder::new(n, &dir.path().join("counts")).unwrap();
     for &col in cols {
         let mut cb = b.add_col().unwrap();
-        for (slot, &v) in col.iter().enumerate() { cb.set(slot, v); }
+        for (slot, &v) in col.iter().enumerate() {
+            cb.set(slot, v);
+        }
         cb.close().unwrap();
     }
     b.close().unwrap();
-    let m = PersistentCompactIntMatrix::open(dir.path()).unwrap();
+    let m = PersistentIntMatrix::open(dir.path()).unwrap();
     (dir, m)
 }
 
@@ -30,7 +31,9 @@ fn make_bit_matrix(cols: &[&[bool]]) -> (tempfile::TempDir, PersistentBitMatrix)
     let mut b = PersistentBitMatrixBuilder::new(n, &presence).unwrap();
     for &col in cols {
         let mut cb = b.add_col().unwrap();
-        for (slot, &v) in col.iter().enumerate() { cb.set(slot, v); }
+        for (slot, &v) in col.iter().enumerate() {
+            cb.set(slot, v);
+        }
         cb.close().unwrap();
     }
     b.close().unwrap();
@@ -115,9 +118,13 @@ fn mask_with_zeros_selected_slots() {
     // count vec [10, 20, 30, 40], mask [T, F, T, F] → [10, 0, 30, 0]
     let dir = tempdir().unwrap();
     let mut v = PersistentCompactIntVecBuilder::new(4, &dir.path().join("v.pciv")).unwrap();
-    v.set(0, 10); v.set(1, 20); v.set(2, 30); v.set(3, 40);
+    v.set(0, 10);
+    v.set(1, 20);
+    v.set(2, 30);
+    v.set(3, 40);
     let mut mask = PersistentBitVecBuilder::new(4, &dir.path().join("m.pbiv")).unwrap();
-    mask.set(0, true); mask.set(2, true);
+    mask.set(0, true);
+    mask.set(2, true);
     v.mask_with(mask.view());
     v.close().unwrap();
     let r = PersistentCompactIntVec::open(&dir.path().join("v.pciv")).unwrap();
@@ -132,9 +139,12 @@ fn mask_with_overflow_slot_zeroed() {
     // overflow slot (value 500) masked out → removed from overflow, primary=0
     let dir = tempdir().unwrap();
     let mut v = PersistentCompactIntVecBuilder::new(3, &dir.path().join("v.pciv")).unwrap();
-    v.set(0, 10); v.set(1, 500); v.set(2, 5);
+    v.set(0, 10);
+    v.set(1, 500);
+    v.set(2, 5);
     let mut mask = PersistentBitVecBuilder::new(3, &dir.path().join("m.pbiv")).unwrap();
-    mask.set(0, true); mask.set(2, true);  // slot 1 masked out
+    mask.set(0, true);
+    mask.set(2, true); // slot 1 masked out
     v.mask_with(mask.view());
     v.close().unwrap();
     let r = PersistentCompactIntVec::open(&dir.path().join("v.pciv")).unwrap();
@@ -142,14 +152,20 @@ fn mask_with_overflow_slot_zeroed() {
     assert_eq!(r.get(1), 0);
     assert_eq!(r.get(2), 5);
     let ov: Vec<_> = r.view().overflow_entries().collect();
-    assert!(ov.is_empty(), "overflow entry for masked-out slot should be gone");
+    assert!(
+        ov.is_empty(),
+        "overflow entry for masked-out slot should be gone"
+    );
 }
 
 #[test]
 fn mask_with_all_ones_is_noop() {
     let dir = tempdir().unwrap();
     let mut v = PersistentCompactIntVecBuilder::new(4, &dir.path().join("v.pciv")).unwrap();
-    v.set(0, 300); v.set(1, 1); v.set(2, 0); v.set(3, 42);
+    v.set(0, 300);
+    v.set(1, 1);
+    v.set(2, 0);
+    v.set(3, 42);
     let mask = PersistentBitVecBuilder::new_ones(4, &dir.path().join("m.pbiv")).unwrap();
     v.mask_with(mask.view());
     v.close().unwrap();
@@ -167,9 +183,9 @@ fn bit_partial_group_presence_count() {
     // col0=[T,F,T,F], col1=[T,T,F,F], col2=[F,T,T,F]
     // group {0,1,2}: counts = [2, 2, 2, 0]
     let (_d, m) = make_bit_matrix(&[
-        &[true, false, true,  false],
-        &[true, true,  false, false],
-        &[false,true,  true,  false],
+        &[true, false, true, false],
+        &[true, true, false, false],
+        &[false, true, true, false],
     ]);
     let g = ColGroup::new("g", vec![0, 1, 2]);
     let result = m.partial_group_presence_count(&g, 1).unwrap();
@@ -184,10 +200,7 @@ fn bit_partial_group_presence_count() {
 #[test]
 fn bit_partial_group_any() {
     // col0=[T,F,F], col1=[F,F,T], group {0,1}: any = [T, F, T]
-    let (_d, m) = make_bit_matrix(&[
-        &[true, false, false],
-        &[false, false, true],
-    ]);
+    let (_d, m) = make_bit_matrix(&[&[true, false, false], &[false, false, true]]);
     let g = ColGroup::new("g", vec![0, 1]);
     let result = m.partial_group_any(&g, 1).unwrap();
     assert_eq!(result.get(0), true);
diff --git a/src/obicompactvec/src/tests/intmatrix.rs b/src/obicompactvec/src/tests/intmatrix.rs
index 1e9cb573..51aecb36 100644
--- a/src/obicompactvec/src/tests/intmatrix.rs
+++ b/src/obicompactvec/src/tests/intmatrix.rs
@@ -1,9 +1,12 @@
 use tempfile::tempdir;
 
-use crate::{pack_compact_int_matrix, pack_sparse_compact_int_matrix, PersistentCompactIntMatrix, PersistentCompactIntMatrixBuilder, PersistentCompactIntVec, PersistentCompactIntVecBuilder, StorageKind};
 use crate::traits::CountPartials;
+use crate::{
+    PersistentCompactIntMatrixBuilder, PersistentCompactIntVec, PersistentCompactIntVecBuilder,
+    PersistentIntMatrix, StorageKind, pack_compact_int_matrix, pack_sparse_compact_int_matrix,
+};
 
-fn make_matrix(cols: &[&[u32]]) -> (tempfile::TempDir, PersistentCompactIntMatrix) {
+fn make_matrix(cols: &[&[u32]]) -> (tempfile::TempDir, PersistentIntMatrix) {
     let n = cols.first().map_or(0, |c| c.len());
     let dir = tempdir().unwrap();
     let mut b = PersistentCompactIntMatrixBuilder::new(n, &dir.path().join("counts")).unwrap();
@@ -15,7 +18,7 @@ fn make_matrix(cols: &[&[u32]]) -> (tempfile::TempDir, PersistentCompactIntMatri
         cb.close().unwrap();
     }
     b.close().unwrap();
-    let m = PersistentCompactIntMatrix::open(dir.path()).unwrap();
+    let m = PersistentIntMatrix::open(dir.path()).unwrap();
     (dir, m)
 }
 
@@ -31,7 +34,7 @@ fn single_col_roundtrip() {
     col.close().unwrap();
     b.close().unwrap();
 
-    let m = PersistentCompactIntMatrix::open(dir.path()).unwrap();
+    let m = PersistentIntMatrix::open(dir.path()).unwrap();
     assert_eq!(m.n_cols(), 1);
     assert_eq!(m.n(), 4);
     assert_eq!(&*m.row(0), &[10u32]);
@@ -45,14 +48,18 @@ fn two_cols_roundtrip() {
     let dir = tempdir().unwrap();
     let mut b = PersistentCompactIntMatrixBuilder::new(3, &dir.path().join("counts")).unwrap();
     let mut col0 = b.add_col().unwrap();
-    col0.set(0, 1); col0.set(1, 2); col0.set(2, 3);
+    col0.set(0, 1);
+    col0.set(1, 2);
+    col0.set(2, 3);
     col0.close().unwrap();
     let mut col1 = b.add_col().unwrap();
-    col1.set(0, 10); col1.set(1, 20); col1.set(2, 30);
+    col1.set(0, 10);
+    col1.set(1, 20);
+    col1.set(2, 30);
     col1.close().unwrap();
     b.close().unwrap();
 
-    let m = PersistentCompactIntMatrix::open(dir.path()).unwrap();
+    let m = PersistentIntMatrix::open(dir.path()).unwrap();
     assert_eq!(m.n_cols(), 2);
     assert_eq!(&*m.row(0), &[1u32, 10]);
     assert_eq!(&*m.row(1), &[2u32, 20]);
@@ -66,7 +73,9 @@ fn resume_continues_n_cols_and_appends_columns() {
 
     let mut b = PersistentCompactIntMatrixBuilder::new(3, &counts).unwrap();
     let mut col0 = b.add_col().unwrap();
-    col0.set(0, 1); col0.set(1, 2); col0.set(2, 3);
+    col0.set(0, 1);
+    col0.set(1, 2);
+    col0.set(2, 3);
     col0.close().unwrap();
     b.close().unwrap();
 
@@ -74,11 +83,13 @@ fn resume_continues_n_cols_and_appends_columns() {
     assert_eq!(resumed.n(), 3);
     assert_eq!(resumed.n_cols(), 1);
     let mut col1 = resumed.add_col().unwrap();
-    col1.set(0, 10); col1.set(1, 20); col1.set(2, 30);
+    col1.set(0, 10);
+    col1.set(1, 20);
+    col1.set(2, 30);
     col1.close().unwrap();
     resumed.close().unwrap();
 
-    let m = PersistentCompactIntMatrix::open(dir.path()).unwrap();
+    let m = PersistentIntMatrix::open(dir.path()).unwrap();
     assert_eq!(m.n_cols(), 2);
     assert_eq!(&*m.row(0), &[1u32, 10]);
     assert_eq!(&*m.row(1), &[2u32, 20]);
@@ -90,17 +101,21 @@ fn resume_twice_keeps_appending() {
     let dir = tempdir().unwrap();
     let counts = dir.path().join("counts");
 
-    PersistentCompactIntMatrixBuilder::new(2, &counts).unwrap().close().unwrap();
+    PersistentCompactIntMatrixBuilder::new(2, &counts)
+        .unwrap()
+        .close()
+        .unwrap();
 
     for v in [1u32, 2, 3] {
         let mut b = PersistentCompactIntMatrixBuilder::resume(&counts).unwrap();
         let mut col = b.add_col().unwrap();
-        col.set(0, v); col.set(1, v * 10);
+        col.set(0, v);
+        col.set(1, v * 10);
         col.close().unwrap();
         b.close().unwrap();
     }
 
-    let m = PersistentCompactIntMatrix::open(dir.path()).unwrap();
+    let m = PersistentIntMatrix::open(dir.path()).unwrap();
     assert_eq!(m.n_cols(), 3);
     assert_eq!(&*m.row(0), &[1u32, 2, 3]);
     assert_eq!(&*m.row(1), &[10u32, 20, 30]);
@@ -111,11 +126,12 @@ fn col_accessor() {
     let dir = tempdir().unwrap();
     let mut b = PersistentCompactIntMatrixBuilder::new(2, &dir.path().join("counts")).unwrap();
     let mut col0 = b.add_col().unwrap();
-    col0.set(0, 5); col0.set(1, 7);
+    col0.set(0, 5);
+    col0.set(1, 7);
     col0.close().unwrap();
     b.close().unwrap();
 
-    let m = PersistentCompactIntMatrix::open(dir.path()).unwrap();
+    let m = PersistentIntMatrix::open(dir.path()).unwrap();
     assert_eq!(m.col(0).get(0), 5);
     assert_eq!(m.col(0).get(1), 7);
 }
@@ -126,7 +142,7 @@ fn zero_cols_roundtrip() {
     let b = PersistentCompactIntMatrixBuilder::new(10, &dir.path().join("counts")).unwrap();
     b.close().unwrap();
 
-    let m = PersistentCompactIntMatrix::open(dir.path()).unwrap();
+    let m = PersistentIntMatrix::open(dir.path()).unwrap();
     assert_eq!(m.n_cols(), 0);
     assert_eq!(m.n(), 10);
 }
@@ -139,7 +155,9 @@ fn bray_dist_matrix_symmetry_and_diagonal() {
     let (_d, m) = make_matrix(&[&[1, 0, 1], &[1, 1, 0], &[0, 1, 1]]);
     let dm = m.bray_dist_matrix();
     let n = m.n_cols();
-    for i in 0..n { assert_eq!(dm[[i, i]], 0.0, "diagonal"); }
+    for i in 0..n {
+        assert_eq!(dm[[i, i]], 0.0, "diagonal");
+    }
     for i in 0..n {
         for j in 0..n {
             assert!((dm[[i, j]] - dm[[j, i]]).abs() < 1e-12, "symmetry");
@@ -174,7 +192,7 @@ fn jaccard_dist_matrix_values_match_pairwise() {
 #[test]
 fn partial_bray_dist_matrix_consistent() {
     let (_d, m) = make_matrix(&[&[1, 0, 1], &[1, 1, 0], &[0, 1, 1]]);
-    let sum_min  = m.partial_bray_dist_matrix();
+    let sum_min = m.partial_bray_dist_matrix();
     let col_sums = m.sum();
     let n = m.n_cols();
 
@@ -189,7 +207,11 @@ fn partial_bray_dist_matrix_consistent() {
     for i in 0..n {
         for j in i + 1..n {
             let denom = col_sums[i] + col_sums[j];
-            let dist = if denom == 0 { 0.0 } else { 1.0 - 2.0 * sum_min[[i, j]] as f64 / denom as f64 };
+            let dist = if denom == 0 {
+                0.0
+            } else {
+                1.0 - 2.0 * sum_min[[i, j]] as f64 / denom as f64
+            };
             let expected = m.col(i).bray_dist(m.col(j));
             assert!((dist - expected).abs() < 1e-12, "[{i},{j}]");
         }
@@ -249,13 +271,18 @@ fn partial_relfreq_bray_matches_full() {
     let (_d, m) = make_matrix(&[&[1, 0, 2], &[0, 1, 1], &[1, 1, 0]]);
     let col_sums = m.sum();
     let partial = m.partial_relfreq_bray_dist_matrix(&col_sums);
-    let full    = m.relfreq_bray_dist_matrix();
+    let full = m.relfreq_bray_dist_matrix();
     let n = m.n_cols();
     // partial[i,j] = sum_min_relfreq; full[i,j] = 1 - sum_min_relfreq (off-diagonal only)
     for i in 0..n {
         for j in 0..n {
-            if i == j { continue; }
-            assert!((partial[[i, j]] - (1.0 - full[[i, j]])).abs() < 1e-12, "[{i},{j}]");
+            if i == j {
+                continue;
+            }
+            assert!(
+                (partial[[i, j]] - (1.0 - full[[i, j]])).abs() < 1e-12,
+                "[{i},{j}]"
+            );
         }
     }
 }
@@ -265,12 +292,15 @@ fn partial_relfreq_euclidean_matches_full() {
     let (_d, m) = make_matrix(&[&[3, 0], &[0, 4], &[1, 1]]);
     let col_sums = m.sum();
     let partial = m.partial_relfreq_euclidean_dist_matrix(&col_sums);
-    let full    = m.relfreq_euclidean_dist_matrix();
+    let full = m.relfreq_euclidean_dist_matrix();
     let n = m.n_cols();
     for i in 0..n {
         for j in 0..n {
             // partial = squared euclidean; full = sqrt(partial)
-            assert!((partial[[i, j]].sqrt() - full[[i, j]]).abs() < 1e-12, "[{i},{j}]");
+            assert!(
+                (partial[[i, j]].sqrt() - full[[i, j]]).abs() < 1e-12,
+                "[{i},{j}]"
+            );
         }
     }
 }
@@ -280,12 +310,15 @@ fn partial_hellinger_matches_full() {
     let (_d, m) = make_matrix(&[&[3, 0], &[0, 4], &[1, 1]]);
     let col_sums = m.sum();
     let partial = m.partial_hellinger_euclidean_dist_matrix(&col_sums);
-    let full    = m.hellinger_dist_matrix();
+    let full = m.hellinger_dist_matrix();
     let n = m.n_cols();
     for i in 0..n {
         for j in 0..n {
             // partial / sqrt(2) gives the Hellinger distance
-            assert!((partial[[i, j]].sqrt() / std::f64::consts::SQRT_2 - full[[i, j]]).abs() < 1e-12, "[{i},{j}]");
+            assert!(
+                (partial[[i, j]].sqrt() / std::f64::consts::SQRT_2 - full[[i, j]]).abs() < 1e-12,
+                "[{i},{j}]"
+            );
         }
     }
 }
@@ -295,7 +328,7 @@ fn col_view_packed_values() {
     // Build Columnar with overflow values (≥ 255), pack, reopen as Packed, exercise col_view().
     let (dir, _col) = make_matrix(&[&[10, 300, 500], &[200, 50, 1000]]);
     pack_compact_int_matrix(&dir.path().join("counts")).unwrap();
-    let m = PersistentCompactIntMatrix::open(dir.path()).unwrap();
+    let m = PersistentIntMatrix::open(dir.path()).unwrap();
 
     // col 0: [10, 300, 500] — two overflow slots
     let v0 = m.col_view(0);
@@ -326,10 +359,10 @@ fn col_view_packed_matches_columnar() {
     // Re-build in a separate dir so we can pack without touching m_col's files.
     let (dir_pack, _) = make_matrix(data);
     pack_compact_int_matrix(&dir_pack.path().join("counts")).unwrap();
-    let m_pack = PersistentCompactIntMatrix::open(dir_pack.path()).unwrap();
+    let m_pack = PersistentIntMatrix::open(dir_pack.path()).unwrap();
 
     for c in 0..data.len() {
-        let col_ref  = m_col.col(c);
+        let col_ref = m_col.col(c);
         let col_view = m_pack.col_view(c);
         assert_eq!(col_view.len(), col_ref.len());
         for s in 0..col_ref.len() {
@@ -337,7 +370,7 @@ fn col_view_packed_matches_columnar() {
         }
         assert_eq!(col_view.sum(), col_ref.sum(), "col={c} sum");
         let mut ov_view: Vec<(usize, u32)> = col_view.overflow_entries().collect();
-        let mut ov_ref:  Vec<(usize, u32)> = col_ref.view().overflow_entries().collect();
+        let mut ov_ref: Vec<(usize, u32)> = col_ref.view().overflow_entries().collect();
         ov_view.sort_unstable_by_key(|&(s, _)| s);
         ov_ref.sort_unstable_by_key(|&(s, _)| s);
         assert_eq!(ov_view, ov_ref, "col={c} overflow_entries");
@@ -355,7 +388,7 @@ fn nonzero_iter_matches_row() {
     let (dir_col, m_col) = make_matrix(data);
     let (dir_pack, _) = make_matrix(data);
     pack_compact_int_matrix(&dir_pack.path().join("counts")).unwrap();
-    let m_pack = PersistentCompactIntMatrix::open(dir_pack.path()).unwrap();
+    let m_pack = PersistentIntMatrix::open(dir_pack.path()).unwrap();
 
     let slots = [4usize, 0, 3, 1];
     let mut expected: Vec<(usize, usize, u32)> = Vec::new();
@@ -390,7 +423,7 @@ fn sparse_roundtrip_matches_columnar() {
     let (dir_col, m_col) = make_matrix(data);
     let (dir_sparse, _) = make_matrix(data);
     pack_sparse_compact_int_matrix(&dir_sparse.path().join("counts")).unwrap();
-    let m_sparse = PersistentCompactIntMatrix::open(dir_sparse.path()).unwrap();
+    let m_sparse = PersistentIntMatrix::open(dir_sparse.path()).unwrap();
     assert_eq!(m_sparse.storage_kind(), StorageKind::Sparse);
 
     assert_eq!(m_sparse.n(), m_col.n());
@@ -441,7 +474,7 @@ fn sparse_count_partials_match_dense() {
     let (dir_col, m_col) = make_matrix(data);
     let (dir_sparse, _) = make_matrix(data);
     pack_sparse_compact_int_matrix(&dir_sparse.path().join("counts")).unwrap();
-    let m_sparse = PersistentCompactIntMatrix::open(dir_sparse.path()).unwrap();
+    let m_sparse = PersistentIntMatrix::open(dir_sparse.path()).unwrap();
     assert_eq!(m_sparse.storage_kind(), StorageKind::Sparse);
 
     let n = m_col.n_cols();
@@ -461,7 +494,11 @@ fn sparse_count_partials_match_dense() {
     let eucl_sparse = m_sparse.partial_euclidean_dist_matrix();
     for i in 0..n {
         for j in 0..n {
-            close(eucl_col[[i, j]], eucl_sparse[[i, j]], &format!("partial_euclidean[{i},{j}]"));
+            close(
+                eucl_col[[i, j]],
+                eucl_sparse[[i, j]],
+                &format!("partial_euclidean[{i},{j}]"),
+            );
         }
     }
 
@@ -469,9 +506,16 @@ fn sparse_count_partials_match_dense() {
     // (support shortcut), and >1 (general row-major path).
     for threshold in [0u32, 1, 2, 3] {
         let (inter_col, union_col) = m_col.partial_threshold_jaccard_dist_matrix(threshold);
-        let (inter_sparse, union_sparse) = m_sparse.partial_threshold_jaccard_dist_matrix(threshold);
-        assert_eq!(inter_col, inter_sparse, "partial_threshold_jaccard inter, threshold={threshold}");
-        assert_eq!(union_col, union_sparse, "partial_threshold_jaccard union, threshold={threshold}");
+        let (inter_sparse, union_sparse) =
+            m_sparse.partial_threshold_jaccard_dist_matrix(threshold);
+        assert_eq!(
+            inter_col, inter_sparse,
+            "partial_threshold_jaccard inter, threshold={threshold}"
+        );
+        assert_eq!(
+            union_col, union_sparse,
+            "partial_threshold_jaccard union, threshold={threshold}"
+        );
     }
 
     // partial_relfreq_bray
@@ -479,7 +523,11 @@ fn sparse_count_partials_match_dense() {
     let rfb_sparse = m_sparse.partial_relfreq_bray_dist_matrix(&global);
     for i in 0..n {
         for j in 0..n {
-            close(rfb_col[[i, j]], rfb_sparse[[i, j]], &format!("partial_relfreq_bray[{i},{j}]"));
+            close(
+                rfb_col[[i, j]],
+                rfb_sparse[[i, j]],
+                &format!("partial_relfreq_bray[{i},{j}]"),
+            );
         }
     }
 
@@ -488,7 +536,11 @@ fn sparse_count_partials_match_dense() {
     let rfe_sparse = m_sparse.partial_relfreq_euclidean_dist_matrix(&global);
     for i in 0..n {
         for j in 0..n {
-            close(rfe_col[[i, j]], rfe_sparse[[i, j]], &format!("partial_relfreq_euclidean[{i},{j}]"));
+            close(
+                rfe_col[[i, j]],
+                rfe_sparse[[i, j]],
+                &format!("partial_relfreq_euclidean[{i},{j}]"),
+            );
         }
     }
 
@@ -497,7 +549,11 @@ fn sparse_count_partials_match_dense() {
     let hel_sparse = m_sparse.partial_hellinger_euclidean_dist_matrix(&global);
     for i in 0..n {
         for j in 0..n {
-            close(hel_col[[i, j]], hel_sparse[[i, j]], &format!("partial_hellinger[{i},{j}]"));
+            close(
+                hel_col[[i, j]],
+                hel_sparse[[i, j]],
+                &format!("partial_hellinger[{i},{j}]"),
+            );
         }
     }
 
@@ -514,7 +570,7 @@ fn sparse_roundtrip_from_packed() {
     let (dir_sparse, _) = make_matrix(data);
     pack_compact_int_matrix(&dir_sparse.path().join("counts")).unwrap();
     pack_sparse_compact_int_matrix(&dir_sparse.path().join("counts")).unwrap();
-    let m_sparse = PersistentCompactIntMatrix::open(dir_sparse.path()).unwrap();
+    let m_sparse = PersistentIntMatrix::open(dir_sparse.path()).unwrap();
     assert_eq!(m_sparse.storage_kind(), StorageKind::Sparse);
     for slot in 0..m_col.n() {
         assert_eq!(&*m_sparse.row(slot), &*m_col.row(slot), "slot={slot}");
@@ -540,7 +596,10 @@ fn partial_relfreq_bray_additive_across_split() {
     let n = m_full.n_cols();
     for i in 0..n {
         for j in 0..n {
-            assert!((combined[[i, j]] - full_partial[[i, j]]).abs() < 1e-12, "[{i},{j}]");
+            assert!(
+                (combined[[i, j]] - full_partial[[i, j]]).abs() < 1e-12,
+                "[{i},{j}]"
+            );
         }
     }
 }
@@ -548,10 +607,12 @@ fn partial_relfreq_bray_additive_across_split() {
 // ── collect_slots_values tests ────────────────────────────────────────────────────────────
 
 fn make_pciv(counts: &[u32]) -> (tempfile::TempDir, PersistentCompactIntVec) {
-    let dir  = tempdir().unwrap();
+    let dir = tempdir().unwrap();
     let path = dir.path().join("c.pciv");
     let mut b = PersistentCompactIntVecBuilder::new(counts.len(), &path).unwrap();
-    for (i, &v) in counts.iter().enumerate() { b.set(i, v); }
+    for (i, &v) in counts.iter().enumerate() {
+        b.set(i, v);
+    }
     b.close().unwrap();
     let r = PersistentCompactIntVec::open(&path).unwrap();
     (dir, r)
@@ -592,7 +653,10 @@ fn pciv_collect_slots_values_empty() {
 fn pciv_collect_slots_values_out_of_bounds_panics() {
     let (_dir, v) = make_pciv(&[10u32, 20]);
     let result = std::panic::catch_unwind(|| v.collect_slots_values(&[0, 2]));
-    assert!(result.is_err(), "collect_slots_values should panic on out-of-bounds slot");
+    assert!(
+        result.is_err(),
+        "collect_slots_values should panic on out-of-bounds slot"
+    );
 }
 
 // IntSliceView collect_slots_values (same logic, exercised through the view)
diff --git a/src/obicompactvec/src/tests/sparse_intmatrix.rs b/src/obicompactvec/src/tests/sparse_intmatrix.rs
index c4089da8..3c41683e 100644
--- a/src/obicompactvec/src/tests/sparse_intmatrix.rs
+++ b/src/obicompactvec/src/tests/sparse_intmatrix.rs
@@ -1,13 +1,14 @@
 use tempfile::tempdir;
 
 use crate::{
-    pack_compact_int_matrix, pack_sparse_compact_int_matrix, ColumnWeights, PersistentCompactIntMatrix,
-    PersistentCompactIntMatrixBuilder, PersistentSparseCompactIntMatrix, PersistentSparseCompactIntMatrixBuilder,
+    ColumnWeights, PersistentIntMatrix, PersistentCompactIntMatrixBuilder,
+    PersistentSparseCompactIntMatrix, PersistentSparseCompactIntMatrixBuilder,
+    pack_compact_int_matrix, pack_sparse_compact_int_matrix,
 };
 
 /// Builds a dense `PersistentCompactIntMatrix` from column-major `u32` data
 /// — mirrors `tests/intmatrix.rs`'s own `make_matrix` helper.
-fn make_dense(cols: &[&[u32]]) -> (tempfile::TempDir, PersistentCompactIntMatrix) {
+fn make_dense(cols: &[&[u32]]) -> (tempfile::TempDir, PersistentIntMatrix) {
     let n = cols.first().map_or(0, |c| c.len());
     let dir = tempdir().unwrap();
     let counts_dir = dir.path().join("counts");
@@ -20,17 +21,21 @@ fn make_dense(cols: &[&[u32]]) -> (tempfile::TempDir, PersistentCompactIntMatrix
         cb.close().unwrap();
     }
     b.close().unwrap();
-    let m = PersistentCompactIntMatrix::open(dir.path()).unwrap();
+    let m = PersistentIntMatrix::open(dir.path()).unwrap();
     (dir, m)
 }
 
 /// Builds a sparse int matrix directly from row-major `u32` data (one
 /// slice per row, `n_cols` values each) — mirrors `tests/sparse.rs`'s
 /// `make_sparse` helper.
-fn make_sparse(rows: &[&[u32]], n_cols: usize) -> (tempfile::TempDir, PersistentSparseCompactIntMatrix) {
+fn make_sparse(
+    rows: &[&[u32]],
+    n_cols: usize,
+) -> (tempfile::TempDir, PersistentSparseCompactIntMatrix) {
     let dir = tempdir().unwrap();
     let sparse_dir = dir.path().join("sparse");
-    let mut b = PersistentSparseCompactIntMatrixBuilder::new(rows.len(), n_cols, &sparse_dir).unwrap();
+    let mut b =
+        PersistentSparseCompactIntMatrixBuilder::new(rows.len(), n_cols, &sparse_dir).unwrap();
     let mut cols = Vec::new();
     let mut values = Vec::new();
     for row in rows {
@@ -54,11 +59,11 @@ fn basic_roundtrip_singletons_and_multi() {
     // shares its *support* (columns {0,1}) with another but has different
     // values — the whole point of not deduplicating values.
     let rows: Vec<&[u32]> = vec![
-        &[5, 0, 0, 0],   // singleton: genome 0, value 5
-        &[0, 0, 3, 0],   // singleton: genome 2, value 3
-        &[7, 2, 0, 0],   // multi: {0:7, 1:2}
-        &[0, 0, 4, 9],   // multi: {2:4, 3:9}
-        &[1, 6, 0, 0],   // multi: same support {0,1} as row 2, different values
+        &[5, 0, 0, 0], // singleton: genome 0, value 5
+        &[0, 0, 3, 0], // singleton: genome 2, value 3
+        &[7, 2, 0, 0], // multi: {0:7, 1:2}
+        &[0, 0, 4, 9], // multi: {2:4, 3:9}
+        &[1, 6, 0, 0], // multi: same support {0,1} as row 2, different values
     ];
     let (_dir, m) = make_sparse(&rows, 4);
     assert_eq!(m.n(), 5);
@@ -70,11 +75,7 @@ fn basic_roundtrip_singletons_and_multi() {
 
 #[test]
 fn get_matches_row() {
-    let rows: Vec<&[u32]> = vec![
-        &[3, 0, 5],
-        &[0, 8, 0],
-        &[1, 2, 4],
-    ];
+    let rows: Vec<&[u32]> = vec![&[3, 0, 5], &[0, 8, 0], &[1, 2, 4]];
     let (_dir, m) = make_sparse(&rows, 3);
     for (slot, row) in rows.iter().enumerate() {
         for (c, &expected) in row.iter().enumerate() {
@@ -85,11 +86,7 @@ fn get_matches_row() {
 
 #[test]
 fn fill_row_matches_row() {
-    let rows: Vec<&[u32]> = vec![
-        &[9, 0, 2],
-        &[0, 4, 0],
-        &[1, 1, 1],
-    ];
+    let rows: Vec<&[u32]> = vec![&[9, 0, 2], &[0, 4, 0], &[1, 1, 1]];
     let (_dir, m) = make_sparse(&rows, 3);
     let mut buf = vec![0u32; 3];
     for slot in 0..3 {
@@ -120,11 +117,7 @@ fn fill_sub_matrix_matches_row() {
 
 #[test]
 fn nonzero_iter_matches_row() {
-    let rows: Vec<&[u32]> = vec![
-        &[9, 0, 2],
-        &[0, 4, 0],
-        &[1, 1, 1],
-    ];
+    let rows: Vec<&[u32]> = vec![&[9, 0, 2], &[0, 4, 0], &[1, 1, 1]];
     let (_dir, m) = make_sparse(&rows, 3);
     let slots = [2usize, 0, 1];
     let mut expected: Vec<(usize, usize, u32)> = Vec::new();
@@ -143,12 +136,7 @@ fn nonzero_iter_matches_row() {
 
 #[test]
 fn sum_and_count_nonzero_match_naive() {
-    let rows: Vec<&[u32]> = vec![
-        &[9, 0, 2],
-        &[0, 4, 0],
-        &[1, 1, 1],
-        &[0, 0, 6],
-    ];
+    let rows: Vec<&[u32]> = vec![&[9, 0, 2], &[0, 4, 0], &[1, 1, 1], &[0, 0, 6]];
     let (_dir, m) = make_sparse(&rows, 3);
     let mut expected_sum = [0u64; 3];
     let mut expected_count = [0u64; 3];
@@ -193,14 +181,21 @@ fn reopen_after_close_matches_original() {
     let rows: Vec<Vec<u32>> = (0..500)
         .map(|i| {
             (0..37)
-                .map(|c| if (i * 7 + c * 3) % 11 == 0 { ((i + c) % 250 + 1) as u32 } else { 0 })
+                .map(|c| {
+                    if (i * 7 + c * 3) % 11 == 0 {
+                        ((i + c) % 250 + 1) as u32
+                    } else {
+                        0
+                    }
+                })
                 .collect()
         })
         .collect();
     let dir = tempdir().unwrap();
     let sparse_dir = dir.path().join("sparse");
     {
-        let mut b = PersistentSparseCompactIntMatrixBuilder::new(rows.len(), 37, &sparse_dir).unwrap();
+        let mut b =
+            PersistentSparseCompactIntMatrixBuilder::new(rows.len(), 37, &sparse_dir).unwrap();
         let mut cols = Vec::new();
         let mut values = Vec::new();
         for row in &rows {
@@ -229,10 +224,7 @@ fn reopen_after_close_matches_original() {
 fn overflow_values_roundtrip() {
     // Values >= 255 exercise the PersistentCompactIntVec overflow path in
     // both the singleton and multi value streams.
-    let rows: Vec<&[u32]> = vec![
-        &[1000, 0, 0],
-        &[0, 50_000, 300],
-    ];
+    let rows: Vec<&[u32]> = vec![&[1000, 0, 0], &[0, 50_000, 300]];
     let (_dir, m) = make_sparse(&rows, 3);
     for (slot, &expected) in rows.iter().enumerate() {
         assert_eq!(&*m.row(slot), expected, "row {slot}");
@@ -246,14 +238,13 @@ fn overflow_values_roundtrip() {
 /// `tests::sparse::pack_sparse_bit_matrix_transposes_columnar_directly`.
 #[test]
 fn pack_sparse_compact_int_matrix_transposes_columnar_directly() {
-    let cols: &[&[u32]] = &[
-        &[9, 0, 2, 0],
-        &[0, 4, 0, 7],
-        &[1, 1, 300, 1],
-    ];
+    let cols: &[&[u32]] = &[&[9, 0, 2, 0], &[0, 4, 0, 7], &[1, 1, 300, 1]];
     let (dir, dense) = make_dense(cols);
     let counts_dir = dir.path().join("counts");
-    assert!(!counts_dir.join("matrix.pcmx").exists(), "still Columnar before packing");
+    assert!(
+        !counts_dir.join("matrix.pcmx").exists(),
+        "still Columnar before packing"
+    );
 
     let expected_rows: Vec<Box<[u32]>> = (0..dense.n()).map(|s| dense.row(s)).collect();
     let n_cols = dense.n_cols();
@@ -262,9 +253,18 @@ fn pack_sparse_compact_int_matrix_transposes_columnar_directly() {
     pack_sparse_compact_int_matrix(&counts_dir).unwrap();
 
     assert!(counts_dir.join("singleton_values.pciv").exists());
-    assert!(!counts_dir.join("meta.json").exists(), "columnar meta.json cleaned up");
-    assert!(!counts_dir.join("col_000000.pciv").exists(), "columnar column files cleaned up");
-    assert!(!counts_dir.join("matrix.pcmx").exists(), "never materialised");
+    assert!(
+        !counts_dir.join("meta.json").exists(),
+        "columnar meta.json cleaned up"
+    );
+    assert!(
+        !counts_dir.join("col_000000.pciv").exists(),
+        "columnar column files cleaned up"
+    );
+    assert!(
+        !counts_dir.join("matrix.pcmx").exists(),
+        "never materialised"
+    );
 
     let sparse = PersistentSparseCompactIntMatrix::open(&counts_dir).unwrap();
     assert_eq!(sparse.n(), expected_rows.len());
@@ -282,10 +282,7 @@ fn pack_sparse_compact_int_matrix_transposes_columnar_directly() {
 /// it's still used as the transpose source and cleaned up afterward.
 #[test]
 fn pack_sparse_compact_int_matrix_from_already_packed_matrix() {
-    let cols: &[&[u32]] = &[
-        &[9, 0, 2],
-        &[0, 4, 300],
-    ];
+    let cols: &[&[u32]] = &[&[9, 0, 2], &[0, 4, 300]];
     let (dir, dense) = make_dense(cols);
     let counts_dir = dir.path().join("counts");
     let expected_rows: Vec<Box<[u32]>> = (0..dense.n()).map(|s| dense.row(s)).collect();
@@ -296,7 +293,10 @@ fn pack_sparse_compact_int_matrix_from_already_packed_matrix() {
     assert!(counts_dir.join("matrix.pcmx").exists());
 
     pack_sparse_compact_int_matrix(&counts_dir).unwrap();
-    assert!(!counts_dir.join("matrix.pcmx").exists(), "packed intermediate cleaned up");
+    assert!(
+        !counts_dir.join("matrix.pcmx").exists(),
+        "packed intermediate cleaned up"
+    );
 
     let sparse = PersistentSparseCompactIntMatrix::open(&counts_dir).unwrap();
     assert_eq!(sparse.n_cols(), n_cols);
diff --git a/src/obikindex/src/layer/content_layer.rs b/src/obikindex/src/layer/content_layer.rs
index 217ce03e..916d2a6c 100644
--- a/src/obikindex/src/layer/content_layer.rs
+++ b/src/obikindex/src/layer/content_layer.rs
@@ -26,7 +26,7 @@ use std::path::{Path, PathBuf};
 
 use crate::layer::utils::LAYERNAME_SUFFIX;
 
-use obicompactvec::{PersistentBitMatrix, PersistentCompactIntMatrix};
+use obicompactvec::{PersistentBitMatrix, PersistentIntMatrix};
 use obikseq::CanonicalKmer;
 
 use crate::index::error::OKIResult;
@@ -63,7 +63,7 @@ pub enum KmerLayer {
     Count {
         dir: PathBuf,
         id: usize,
-        layer: TypedLayer<PersistentCompactIntMatrix>,
+        layer: TypedLayer<PersistentIntMatrix>,
     },
     Presence {
         dir: PathBuf,
@@ -99,7 +99,7 @@ impl KmerLayer {
             already_open => return Ok(already_open),
         };
         if dir.join(COUNTS_DIR).exists() {
-            let layer = TypedLayer::<PersistentCompactIntMatrix>::open(&dir)?;
+            let layer = TypedLayer::<PersistentIntMatrix>::open(&dir)?;
             Ok(KmerLayer::Count { dir, id, layer })
         } else {
             let layer = TypedLayer::<PersistentBitMatrix>::open(&dir)?;
@@ -221,7 +221,10 @@ impl KmerLayer {
     /// format-agnostic column-major fetch, delegating to whichever matrix
     /// this layer actually holds (see `obicompactvec::PersistentBitMatrix`/
     /// `PersistentCompactIntMatrix::nonzero_iter`).
-    pub fn nonzero_iter<'a>(&'a self, slots: &'a [usize]) -> Box<dyn Iterator<Item = (usize, usize, u32)> + 'a> {
+    pub fn nonzero_iter<'a>(
+        &'a self,
+        slots: &'a [usize],
+    ) -> Box<dyn Iterator<Item = (usize, usize, u32)> + 'a> {
         match self {
             KmerLayer::Presence { layer, .. } => layer.nonzero_iter(slots),
             KmerLayer::Count { layer, .. } => layer.nonzero_iter(slots),
diff --git a/src/obikindex/src/layer/tests/typed_layer.rs b/src/obikindex/src/layer/tests/typed_layer.rs
index 7c941999..3de5eb9b 100644
--- a/src/obikindex/src/layer/tests/typed_layer.rs
+++ b/src/obikindex/src/layer/tests/typed_layer.rs
@@ -1,6 +1,6 @@
 use super::*;
 use obicompactvec::PersistentSparseBitMatrixBuilder;
-use obikseq::{set_k, Unitig};
+use obikseq::{Unitig, set_k};
 use obiskio::DEFAULT_BLOCK_BITS;
 use tempfile::tempdir;
 
@@ -13,7 +13,8 @@ fn write_unitigs(dir: &Path, seqs: &[&[u8]]) {
 }
 
 fn all_canonical_kmers(dir: &Path) -> Vec<CanonicalKmer> {
-    UnitigFileReader::open_sequential(&dir.join(UNITIGS_FILE)).unwrap()
+    UnitigFileReader::open_sequential(&dir.join(UNITIGS_FILE))
+        .unwrap()
         .iter_indexed_canonical_kmers()
         .map(|(kmer, _, _)| kmer)
         .collect()
@@ -34,13 +35,17 @@ fn canonical_kmer_iter_matches_reader() {
     let dir = tempdir().unwrap();
     write_unitigs(dir.path(), &[b"AAAACGT", b"TTTTGCA"]);
 
-    let from_iter: Vec<CanonicalKmer> = obiskio::CanonicalKmerIter::new(&dir.path().join(UNITIGS_FILE))
-        .unwrap()
-        .collect();
+    let from_iter: Vec<CanonicalKmer> =
+        obiskio::CanonicalKmerIter::new(&dir.path().join(UNITIGS_FILE))
+            .unwrap()
+            .collect();
     let from_reader: Vec<CanonicalKmer> = all_canonical_kmers(dir.path());
 
     assert_eq!(from_iter.len(), from_reader.len(), "different kmer counts");
-    assert_eq!(from_iter, from_reader, "CanonicalKmerIter and UnitigFileReader disagree");
+    assert_eq!(
+        from_iter, from_reader,
+        "CanonicalKmerIter and UnitigFileReader disagree"
+    );
 }
 
 // ── Generic `TypedLayer<D>` over dense vs. sparse presence storage ───────────────
@@ -64,9 +69,14 @@ fn presence_layer_generic_over_sparse_matches_dense() {
     // kmer iff `(kmer's raw bits + g)` is even. Doesn't need to be
     // biologically meaningful, just the same on both sides of the
     // dense/sparse comparison below.
-    TypedLayer::<PersistentBitMatrix>::build_presence(dir.path(), DEFAULT_BLOCK_BITS, &mode, n_genomes, |kmer, g| {
-        (kmer.raw().wrapping_add(g as u64)) % 2 == 0
-    }).unwrap();
+    TypedLayer::<PersistentBitMatrix>::build_presence(
+        dir.path(),
+        DEFAULT_BLOCK_BITS,
+        &mode,
+        n_genomes,
+        |kmer, g| (kmer.raw().wrapping_add(g as u64)) % 2 == 0,
+    )
+    .unwrap();
 
     let dense_layer = TypedLayer::<PersistentBitMatrix>::open(dir.path()).unwrap();
     assert!(dense_layer.n_cols() >= 1);
@@ -76,10 +86,13 @@ fn presence_layer_generic_over_sparse_matches_dense() {
     // same directory, distinct filenames — see
     // `DevDocMD/architecture/siblings.md`'s sparse-matrix section).
     let dense_matrix = obicompactvec::PersistentBitMatrix::open(dir.path()).unwrap();
-    PersistentSparseBitMatrixBuilder::build_from_dense(&dense_matrix, &dir.path().join(PRESENCE_DIR))
-        .unwrap()
-        .close()
-        .unwrap();
+    PersistentSparseBitMatrixBuilder::build_from_dense(
+        &dense_matrix,
+        &dir.path().join(PRESENCE_DIR),
+    )
+    .unwrap()
+    .close()
+    .unwrap();
 
     let sparse_layer = TypedLayer::<PersistentSparseBitMatrix>::open(dir.path()).unwrap();
 
@@ -88,7 +101,10 @@ fn presence_layer_generic_over_sparse_matches_dense() {
     let n = dense_layer.n();
     assert_eq!(n, sparse_layer.n());
     let slots: Vec<usize> = (0..n).collect();
-    assert_eq!(dense_layer.sub_matrix(&slots), sparse_layer.sub_matrix(&slots));
+    assert_eq!(
+        dense_layer.sub_matrix(&slots),
+        sparse_layer.sub_matrix(&slots)
+    );
 
     // The matrix-agnostic, MPHF-only surface (from the generic
     // `impl<D: LayerData> TypedLayer<D>`) must also agree: same kmer set,
@@ -124,15 +140,25 @@ fn count_layer_transparently_reads_sparse_after_pack() {
     // Deterministic, arbitrary count function — same shape as the presence
     // test's arbitrary predicate, just producing a small count instead of a
     // bool.
-    TypedLayer::<()>::build_with_matrix(dir.path(), DEFAULT_BLOCK_BITS, &mode, false, n_genomes, |kmer| {
-        (0..n_genomes)
-            .map(|g| ((kmer.raw().wrapping_add(g as u64)) % 5) as u32)
-            .collect()
-    })
+    TypedLayer::<()>::build_with_matrix(
+        dir.path(),
+        DEFAULT_BLOCK_BITS,
+        &mode,
+        false,
+        n_genomes,
+        |kmer| {
+            (0..n_genomes)
+                .map(|g| ((kmer.raw().wrapping_add(g as u64)) % 5) as u32)
+                .collect()
+        },
+    )
     .unwrap();
 
-    let dense_layer = TypedLayer::<PersistentCompactIntMatrix>::open(dir.path()).unwrap();
-    assert_eq!(dense_layer.storage_kind(), obicompactvec::StorageKind::Columnar);
+    let dense_layer = TypedLayer::<PersistentIntMatrix>::open(dir.path()).unwrap();
+    assert_eq!(
+        dense_layer.storage_kind(),
+        obicompactvec::StorageKind::Columnar
+    );
     let n = dense_layer.n();
     let slots: Vec<usize> = (0..n).collect();
     let dense_sub = dense_layer.sub_matrix(&slots);
@@ -146,8 +172,11 @@ fn count_layer_transparently_reads_sparse_after_pack() {
     // in production.
     obicompactvec::pack_sparse_compact_int_matrix(&dir.path().join(COUNTS_DIR)).unwrap();
 
-    let sparse_layer = TypedLayer::<PersistentCompactIntMatrix>::open(dir.path()).unwrap();
-    assert_eq!(sparse_layer.storage_kind(), obicompactvec::StorageKind::Sparse);
+    let sparse_layer = TypedLayer::<PersistentIntMatrix>::open(dir.path()).unwrap();
+    assert_eq!(
+        sparse_layer.storage_kind(),
+        obicompactvec::StorageKind::Sparse
+    );
     assert_eq!(sparse_layer.n(), n);
     assert_eq!(sparse_layer.n_cols(), dense_layer.n_cols());
     assert_eq!(sparse_layer.sub_matrix(&slots), dense_sub);
@@ -167,13 +196,20 @@ fn count_layer_reports_count_content_and_columnar_storage() {
     set_k(4);
     let dir = tempdir().unwrap();
     write_unitigs(dir.path(), &[b"AAAACGT"]);
-    TypedLayer::<PersistentCompactIntMatrix>::build(dir.path(), DEFAULT_BLOCK_BITS, &IndexMode::Exact, |_| 1)
-        .unwrap();
-    let layer = TypedLayer::<PersistentCompactIntMatrix>::open(dir.path()).unwrap();
+    TypedLayer::<PersistentIntMatrix>::build(dir.pat
+        h(), DEFAUL
+       T_BLOCK_BITS, &Index
+       Mode::Exact, |_| 1)
+       ,
+    ).unwrap();
+    let layer = TypedLayer::<PersistentIntMatrix>::open(dir.path()).unwrap();
 
     assert_eq!(layer.content(), LayerContent::Count);
     assert_eq!(layer.storage_kind(), obicompactvec::StorageKind::Columnar);
-    assert_eq!(layer.evidence_kind(), crate::layer::mphf_layer::EvidenceKind::Exact);
+    assert_eq!(
+        layer.evidence_kind(),
+        crate::layer::mphf_layer::EvidenceKind::Exact
+    );
 }
 
 #[test]
@@ -181,9 +217,14 @@ fn presence_layer_reports_presence_content_and_columnar_storage() {
     set_k(4);
     let dir = tempdir().unwrap();
     write_unitigs(dir.path(), &[b"AAATCTA", b"CTTCGCC", b"TGATACG"]);
-    TypedLayer::<PersistentBitMatrix>::build_presence(dir.path(), DEFAULT_BLOCK_BITS, &IndexMode::Exact, 2, |kmer, g| {
-        (kmer.raw().wrapping_add(g as u64)) % 2 == 0
-    }).unwrap();
+    TypedLayer::<PersistentBitMatrix>::build_presence(
+        dir.path(),
+        DEFAULT_BLOCK_BITS,
+        &IndexMode::Exact,
+        2,
+        |kmer, g| (kmer.raw().wrapping_add(g as u64)) % 2 == 0,
+    )
+    .unwrap();
     let layer = TypedLayer::<PersistentBitMatrix>::open(dir.path()).unwrap();
 
     assert_eq!(layer.content(), LayerContent::Presence);
diff --git a/src/obikindex/src/layer/typed_layer.rs b/src/obikindex/src/layer/typed_layer.rs
index 27980039..af37d198 100644
--- a/src/obikindex/src/layer/typed_layer.rs
+++ b/src/obikindex/src/layer/typed_layer.rs
@@ -1,7 +1,7 @@
 // use crate::layer::utils::layer_dir;
 use obicompactvec::{
     BinaryMatrix, ColBuilder, MatrixBuilder, PersistentBitMatrix, PersistentBitMatrixBuilder,
-    PersistentCompactIntMatrix, PersistentCompactIntMatrixBuilder, PersistentSparseBitMatrix,
+    PersistentCompactIntMatrixBuilder, PersistentIntMatrix, PersistentSparseBitMatrix,
 };
 use obikseq::CanonicalKmer;
 use obiskio::{UnitigFileReader, UnitigFileWriter};
@@ -47,10 +47,10 @@ impl LayerData for () {
     fn read(&self, _slot: usize) {}
 }
 
-impl LayerData for PersistentCompactIntMatrix {
+impl LayerData for PersistentIntMatrix {
     type Item = Box<[u32]>;
     fn open(layer_dir: &Path) -> OKIResult<Self> {
-        PersistentCompactIntMatrix::open(layer_dir).map_err(OKIError::Io)
+        PersistentIntMatrix::open(layer_dir).map_err(OKIError::Io)
     }
     fn read(&self, slot: usize) -> Box<[u32]> {
         self.row(slot)
@@ -112,7 +112,7 @@ pub trait HasLayerContent {
     const CONTENT: LayerContent;
 }
 
-impl HasLayerContent for PersistentCompactIntMatrix {
+impl HasLayerContent for PersistentIntMatrix {
     const CONTENT: LayerContent = LayerContent::Count;
 }
 
@@ -135,9 +135,9 @@ pub trait HasStorageKind {
     fn storage_kind(&self) -> obicompactvec::StorageKind;
 }
 
-impl HasStorageKind for PersistentCompactIntMatrix {
+impl HasStorageKind for PersistentIntMatrix {
     fn storage_kind(&self) -> obicompactvec::StorageKind {
-        PersistentCompactIntMatrix::storage_kind(self)
+        PersistentIntMatrix::storage_kind(self)
     }
 }
 
@@ -342,7 +342,7 @@ impl TypedLayer<()> {
 
 // ── Mode 2 — count matrix ─────────────────────────────────────────────────────
 
-impl TypedLayer<PersistentCompactIntMatrix> {
+impl TypedLayer<PersistentIntMatrix> {
     pub fn build(
         out_dir: &Path,
         block_bits: u8,
@@ -377,12 +377,12 @@ impl TypedLayer<PersistentCompactIntMatrix> {
 
 // ── Mode 2 — count matrix column append ──────────────────────────────────────
 
-impl TypedLayer<PersistentCompactIntMatrix> {
+impl TypedLayer<PersistentIntMatrix> {
     pub fn append_genome_column(
         layer_dir: &Path,
         value_of: impl Fn(usize) -> u32,
     ) -> OKIResult<()> {
-        PersistentCompactIntMatrix::append_column(&layer_dir.join(COUNTS_DIR), value_of)
+        PersistentIntMatrix::append_column(&layer_dir.join(COUNTS_DIR), value_of)
             .map_err(OKIError::Io)
     }
 
@@ -418,7 +418,10 @@ impl TypedLayer<PersistentCompactIntMatrix> {
 
     /// Every nonzero `(idx into slots, col, value)` triple among `slots` —
     /// delegates to `PersistentCompactIntMatrix::nonzero_iter`.
-    pub fn nonzero_iter<'a>(&'a self, slots: &'a [usize]) -> Box<dyn Iterator<Item = (usize, usize, u32)> + 'a> {
+    pub fn nonzero_iter<'a>(
+        &'a self,
+        slots: &'a [usize],
+    ) -> Box<dyn Iterator<Item = (usize, usize, u32)> + 'a> {
         self.data.nonzero_iter(slots)
     }
 }
@@ -477,7 +480,10 @@ impl<D: LayerData<Item = Box<[bool]>> + BinaryMatrix + obicompactvec::ColumnWeig
 impl TypedLayer<PersistentBitMatrix> {
     /// Every nonzero `(idx into slots, col, value)` triple among `slots` —
     /// delegates to `PersistentBitMatrix::nonzero_iter`.
-    pub fn nonzero_iter<'a>(&'a self, slots: &'a [usize]) -> Box<dyn Iterator<Item = (usize, usize, u32)> + 'a> {
+    pub fn nonzero_iter<'a>(
+        &'a self,
+        slots: &'a [usize],
+    ) -> Box<dyn Iterator<Item = (usize, usize, u32)> + 'a> {
         self.data.nonzero_iter(slots)
     }
 
diff --git a/src/obikindexer/src/extensions/private_builder.rs b/src/obikindexer/src/extensions/private_builder.rs
index 8134b99f..661d9194 100644
--- a/src/obikindexer/src/extensions/private_builder.rs
+++ b/src/obikindexer/src/extensions/private_builder.rs
@@ -24,14 +24,14 @@ use std::fs;
 use std::io;
 use std::path::Path;
 
+use crate::graph_pipeline::{materialize_layer, write_graph_as_unitigs};
 use cacheline_ef::{CachelineEf, CachelineEfVec};
 use epserde::prelude::*;
-use obicompactvec::{PersistentCompactIntMatrix, PersistentCompactIntVec};
+use obicompactvec::{PersistentIntMatrix, PersistentCompactIntVec};
 use obidebruinj::GraphDeBruijn;
 use obikindex::layer::IndexMode;
 use obikindex::layer::{KmerLayer, TypedLayer};
 use obikindex::{KmerIndex, OKIError, OKIResult};
-use crate::graph_pipeline::{materialize_layer, write_graph_as_unitigs};
 use obiskio::{SKError, SKFileMeta, SKFileReader};
 use ptr_hash::{PtrHash, bucket_fn::CubicEps, hash::Xx64};
 
@@ -139,7 +139,9 @@ impl PrivateBuilder for KmerIndex {
         mode: &IndexMode,
         block_bits: u8,
     ) -> Result<usize, SKError> {
-        let layer0 = self.layer0(i).map_err(|e| io::Error::other(e.to_string()))?;
+        let layer0 = self
+            .layer0(i)
+            .map_err(|e| io::Error::other(e.to_string()))?;
         let layer0_dir = layer0.dir();
         let dedup_path = layer0.dereplicated_superkmers_path();
         if !dedup_path.exists() {
@@ -193,15 +195,12 @@ impl PrivateBuilder for KmerIndex {
         let n_kmers = if with_counts {
             let n = write_graph_as_unitigs(g, layer0_dir)
                 .map_err(|e| io::Error::other(e.to_string()))?;
-            TypedLayer::<PersistentCompactIntMatrix>::build(
-                layer0_dir,
-                block_bits,
-                mode,
-                |kmer| match (&mphf1_opt, &counts1_opt) {
+            TypedLayer::<PersistentIntMatrix>::build(layer0_dir, block_bits, mode, |kmer| {
+                match (&mphf1_opt, &counts1_opt) {
                     (Some(mphf), Some(counts)) => counts.get(mphf.index(&kmer.raw())),
                     _ => 1,
-                },
-            )
+                }
+            })
             .map_err(|e| io::Error::other(e.to_string()))?;
             n
         } else {
diff --git a/src/obikmerge/src/partition_merge.rs b/src/obikmerge/src/partition_merge.rs
index 6a60baba..b21ba8e8 100644
--- a/src/obikmerge/src/partition_merge.rs
+++ b/src/obikmerge/src/partition_merge.rs
@@ -34,7 +34,7 @@ fn presence(mode: MergeMode) -> bool {
 mod matrix_builder_tests {
     use tempfile::tempdir;
 
-    use obicompactvec::{PersistentBitMatrix, PersistentCompactIntMatrix};
+    use obicompactvec::{PersistentBitMatrix, PersistentIntMatrix};
 
     use super::{ColBuilder, MatrixBuilder};
 
@@ -90,7 +90,7 @@ mod matrix_builder_tests {
         col.close().unwrap();
         mb.close().unwrap();
 
-        let m = PersistentCompactIntMatrix::open(dir.path()).unwrap();
+        let m = PersistentIntMatrix::open(dir.path()).unwrap();
         assert_eq!(m.n_cols(), 2);
         assert_eq!(&*m.row(0), &[0u32, 7]);
         assert_eq!(&*m.row(1), &[0u32, 42]);
@@ -422,8 +422,13 @@ pub(crate) fn merge_partition(
                 move |data: Pass2Data,
                       push: &PipelineSender<Result<Pass2Data, PipelineError>>,
                       delta: &PipelineSender<isize>| {
-                    if let Pass2Data::SrcLayer((col_offset, src_n, unitigs_path, src_layer, _guard)) =
-                        data
+                    if let Pass2Data::SrcLayer((
+                        col_offset,
+                        src_n,
+                        unitigs_path,
+                        src_layer,
+                        _guard,
+                    )) = data
                     {
                         // _guard dropped at end of block, releasing the slot.
                         // `src_layer` (MPHF + matrix) was already opened up
@@ -455,8 +460,10 @@ pub(crate) fn merge_partition(
                             }
                         }
                         if !batch.is_empty() {
-                            push.send(Ok(Pass2Data::RawBatch((col_offset, src_n, src_layer, batch))))
-                                .ok();
+                            push.send(Ok(Pass2Data::RawBatch((
+                                col_offset, src_n, src_layer, batch,
+                            ))))
+                            .ok();
                             count += 1;
                         }
                         delta.send(count - 1).ok();
@@ -480,8 +487,9 @@ pub(crate) fn merge_partition(
                         // per kmer — matches the underlying matrix's own
                         // column-major layout.
                         let slots = src_layer.hash_batch(&kmers);
-                        let mut cols: Vec<Vec<u32>> =
-                            (0..src_n).map(|_| Vec::with_capacity(kmers.len())).collect();
+                        let mut cols: Vec<Vec<u32>> = (0..src_n)
+                            .map(|_| Vec::with_capacity(kmers.len()))
+                            .collect();
                         src_layer.fill_sub_matrix(&slots, &mut cols);
 
                         // Membership against dst, grouped by dst layer
diff --git a/src/obikphylo/src/matrix_store.rs b/src/obikphylo/src/matrix_store.rs
index 74ddf02f..67054479 100644
--- a/src/obikphylo/src/matrix_store.rs
+++ b/src/obikphylo/src/matrix_store.rs
@@ -1,15 +1,15 @@
+use obicompactvec::{PersistentBitMatrix, PersistentIntMatrix};
+use obikidxcache::LayeredStore;
 use obikindex::OKIResult;
 use obikindex::layer::open_data;
-use obikidxcache::LayeredStore;
-use obicompactvec::{PersistentBitMatrix, PersistentCompactIntMatrix};
 
-use obikindex::load_meta;
 use obikindex::KmerIndex;
+use obikindex::load_meta;
 
 impl KmerIndex {
     /// Open all count matrices for partition `part`, one per layer.
     /// Layers without a `counts/` directory are skipped.
-    pub fn count_store(&self, part: usize) -> OKIResult<LayeredStore<PersistentCompactIntMatrix>> {
+    pub fn count_store(&self, part: usize) -> OKIResult<LayeredStore<PersistentIntMatrix>> {
         let index_dir = self.index_dir(part);
         if !index_dir.exists() {
             return Ok(LayeredStore::new(vec![]));
diff --git a/src/obikselect/src/select_layer.rs b/src/obikselect/src/select_layer.rs
index 8b0a9700..3f1648a3 100644
--- a/src/obikselect/src/select_layer.rs
+++ b/src/obikselect/src/select_layer.rs
@@ -11,8 +11,8 @@ use std::io;
 use std::path::Path;
 
 use obicompactvec::{
-    ColGroup, MatrixBuilder, MatrixGroupOps, PersistentBitMatrix,
-    PersistentCompactIntMatrix, TempBitVec, TempCompactIntVec,
+    ColGroup, MatrixBuilder, MatrixGroupOps, PersistentBitMatrix, PersistentIntMatrix, TempBitVec,
+    TempCompactIntVec,
 };
 use obikindex::layer::{KmerLayer, LayerContent};
 use obikindex::{KmerIndex, OKIError, OKIResult};
@@ -39,13 +39,15 @@ impl AggOp {
     /// `--aggregate-op`.
     pub fn parse(s: &str) -> Result<Self, String> {
         match s.to_lowercase().as_str() {
-            "any"  => Ok(AggOp::Any),
-            "all"  => Ok(AggOp::All),
+            "any" => Ok(AggOp::Any),
+            "all" => Ok(AggOp::All),
             "none" => Ok(AggOp::None),
-            "sum"  => Ok(AggOp::Sum),
-            "min"  => Ok(AggOp::Min),
-            "max"  => Ok(AggOp::Max),
-            other  => Err(format!("unknown aggregation operator: {other}; valid: any, all, none, sum, min, max")),
+            "sum" => Ok(AggOp::Sum),
+            "min" => Ok(AggOp::Min),
+            "max" => Ok(AggOp::Max),
+            other => Err(format!(
+                "unknown aggregation operator: {other}; valid: any, all, none, sum, min, max"
+            )),
         }
     }
 
@@ -75,7 +77,11 @@ enum AggResult {
     Int(TempCompactIntVec),
 }
 
-fn compute_group(mat: &dyn MatrixGroupOps, spec: &OutputCol, threshold: u32) -> io::Result<AggResult> {
+fn compute_group(
+    mat: &dyn MatrixGroupOps,
+    spec: &OutputCol,
+    threshold: u32,
+) -> io::Result<AggResult> {
     let g = ColGroup::new(spec.label.clone(), spec.indices.clone());
     Ok(match spec.op {
         AggOp::Any => AggResult::Bit(mat.partial_group_any(&g, threshold)?),
@@ -145,18 +151,23 @@ pub(crate) fn select_partition(
 
         let group_mat: Box<dyn MatrixGroupOps> = match src_layer.content() {
             LayerContent::Count => {
-                Box::new(PersistentCompactIntMatrix::open(src_layer.dir()).map_err(OKIError::Io)?)
+                Box::new(PersistentIntMatrix::open(src_layer.dir()).map_err(OKIError::Io)?)
             }
             LayerContent::Presence => {
                 Box::new(PersistentBitMatrix::open(src_layer.dir()).map_err(OKIError::Io)?)
             }
         };
 
-        let data_subdir = if output_presence { "presence" } else { "counts" };
+        let data_subdir = if output_presence {
+            "presence"
+        } else {
+            "counts"
+        };
         let data_dir = dst_layer_dir.join(data_subdir);
         fs::create_dir_all(&data_dir).map_err(OKIError::Io)?;
 
-        let mut builder = MatrixBuilder::new(output_presence, n, &data_dir).map_err(OKIError::Io)?;
+        let mut builder =
+            MatrixBuilder::new(output_presence, n, &data_dir).map_err(OKIError::Io)?;
         for spec in specs {
             let r = compute_group(group_mat.as_ref(), spec, threshold).map_err(OKIError::Io)?;
             add_result(&mut builder, r).map_err(OKIError::Io)?;