diff --git a/interactive/Cargo.toml b/interactive/Cargo.toml
index 1673d1440..adb8ea20a 100644
--- a/interactive/Cargo.toml
+++ b/interactive/Cargo.toml
@@ -14,7 +14,7 @@ workspace = true
 [dependencies]
 columnar = { workspace = true }
 # The columnar kernels for the interpreted backend, pinned by git rev.
-corgi = { git = "https://github.com/frankmcsherry/WIP", rev = "578ef3fe79fdaa813ba0c721c08f60323f22d420", features = ["serde"] }
+corgi = { git = "https://github.com/frankmcsherry/WIP", rev = "de0f2ac91d31ac63641035e5a5bb1b5640fe9424", features = ["serde"] }
 differential-dataflow = { workspace = true }
 mimalloc = "0.1.48"
 serde = { version = "1.0", features = ["derive"] }
diff --git a/interactive/src/backend/corgi.rs b/interactive/src/backend/corgi.rs
index 4422b235c..0b48a19ef 100644
--- a/interactive/src/backend/corgi.rs
+++ b/interactive/src/backend/corgi.rs
@@ -203,10 +203,7 @@ fn apply_ops(mut c: CC, ops: &[LinearOp], level: usize, plans: &mut [Plan]) -> C
                 // carrying key/time/diff across. No per-row eval, no transcode.
                 let (bounds, elems) =
                     corgi::eval_graph(g, CValue::Prod(vec![c.keys.clone(), c.vals])).into_list("flatmap list").unwrap();
-                let ends: Vec<usize> = match &bounds {
-                    corgi::Bounds::Offsets(v) => v.clone(),
-                    corgi::Bounds::Stride(k, rows) => (1..=*rows).map(|i| i * k).collect(),
-                };
+                let ends: Vec<usize> = bounds.to_vec();
                 let total = ends.last().copied().unwrap_or(0);
                 let (mut reps, mut pos) = (Vec::with_capacity(total), Vec::with_capacity(total));
                 let mut start = 0usize;
diff --git a/interactive/src/corgi/bytes.rs b/interactive/src/corgi/bytes.rs
index 3275a9dfe..c7f848c80 100644
--- a/interactive/src/corgi/bytes.rs
+++ b/interactive/src/corgi/bytes.rs
@@ -226,8 +226,8 @@ mod test {
             let c = container_of(name, updates);
             let (keys, vals) = (c.keys.clone(), c.vals.clone());
             let back = round_trip(&c);
-            assert_eq!(corgi::arrange::hash_rows(&back.keys), corgi::arrange::hash_rows(&keys), "{name} keys");
-            assert_eq!(corgi::arrange::hash_rows(&back.vals), corgi::arrange::hash_rows(&vals), "{name} vals");
+            assert_eq!(corgi::hash(&back.keys), corgi::hash(&keys), "{name} keys");
+            assert_eq!(corgi::hash(&back.vals), corgi::hash(&vals), "{name} vals");
         }
     }
 
diff --git a/interactive/src/corgi/chunk.rs b/interactive/src/corgi/chunk.rs
index a7aea6b13..79eb4562d 100644
--- a/interactive/src/corgi/chunk.rs
+++ b/interactive/src/corgi/chunk.rs
@@ -28,7 +28,7 @@ use timely::progress::frontier::AntichainRef;
 use differential_dataflow::difference::Semigroup;
 use differential_dataflow::trace::chunk::{pack, Chunk, ChunkBatch};
 
-use corgi::arrange::{compare_at, compare_idx, gather, gather_lanes, group_bounds, sort_perm};
+use corgi::arrange::{compare_adjacent, compare_at, gather, gather_lanes, group_bounds, sort_perm};
 use corgi::Value as CValue;
 
 use columnar::Columnar;
@@ -348,7 +348,7 @@ where
 /// (summing diffs, dropping zeros). Returns a sorted+consolidated `(keys, vals, times, diffs)`.
 ///
 /// Multi-record: one columnar `sort_perm` (discrimination sort) orders by `(key, val)`, one batched
-/// `compare_idx` flags adjacent-equal runs; only the small per-run *time* tiebreak is a Rust sort
+/// `compare_adjacent` flags adjacent-equal runs; only the small per-run *time* tiebreak is a Rust sort
 /// (time is not a corgi type). No per-pair `compare_at`.
 fn sort_consolidate<T, R>(keys: CValue, vals: CValue, times: Vec<T>, diffs: Vec<R>) -> (CValue, CValue, Vec<T>, Vec<R>)
 where
@@ -366,13 +366,9 @@ where
     let times_s: Vec<T> = perm.iter().map(|&i| times[i].clone()).collect();
     let diffs_s: Vec<R> = perm.iter().map(|&i| diffs[i].clone()).collect();
     // Batched adjacent-equality over the kv-sorted column: `adj[m] == 0` iff `kv_s[m] == kv_s[m+1]`.
-    let adj: Vec<i8> = if n > 1 {
-        let left: Vec<usize> = (0..n - 1).collect();
-        let right: Vec<usize> = (1..n).collect();
-        compare_idx(&kv_s, &kv_s, &left, &right)
-    } else {
-        Vec::new()
-    };
+    // Naming the pattern rather than writing out the two index columns: corgi reads both sides
+    // densely, and the `i`/`i+1` index vectors this used to build are not built at all.
+    let adj: Vec<i8> = compare_adjacent(&kv_s);
 
     // Walk maximal equal-`(key,val)` runs; within each, order by time and consolidate equal times.
     let (mut keep, mut ot, mut od) = (Vec::new(), Vec::new(), Vec::new());
@@ -497,7 +493,7 @@ pub fn present_key(keys: CValue) -> CValue {
     if corgi::arrange::leaf_slice(&keys).is_some() {
         return keys;
     }
-    let hashes = corgi::hash(&keys).into_u64("present_key").unwrap();
+    let hashes = corgi::hash(&keys);
     CValue::Prod(vec![CValue::u64(hashes), keys])
 }
 
diff --git a/interactive/src/corgi/exchange.rs b/interactive/src/corgi/exchange.rs
index aaa875ff9..110ea0fef 100644
--- a/interactive/src/corgi/exchange.rs
+++ b/interactive/src/corgi/exchange.rs
@@ -111,7 +111,7 @@ impl<T: Clone + 'static, R: Clone + 'static> Distributor<CorgiContainer<T, R>> f
         }
         let peers = pushers.len();
 
-        let ids = corgi::hash(&container.keys).into_u64("corgi exchange: key hash").unwrap();
+        let ids = corgi::hash(&container.keys);
         self.counting_sort(&ids, peers);
 
         // Whole-container fast path. When every row shares a destination — a batch narrower than
diff --git a/interactive/src/corgi/logic.rs b/interactive/src/corgi/logic.rs
index 5e20aafb2..434539b71 100644
--- a/interactive/src/corgi/logic.rs
+++ b/interactive/src/corgi/logic.rs
@@ -130,10 +130,7 @@ pub fn untranscode(col: CValue, shape: &Shape) -> Vec<DValue> {
                 other => panic!("untranscode: expected List, got {other:?}"),
             };
             let flat = untranscode(vals, elem);
-            let ends: Vec<usize> = match &bounds {
-                corgi::Bounds::Offsets(v) => v.clone(),
-                corgi::Bounds::Stride(k, rows) => (1..=*rows).map(|i| i * k).collect(),
-            };
+            let ends: Vec<usize> = bounds.to_vec();
             let mut out = Vec::with_capacity(ends.len());
             let mut start = 0usize;
             for end in ends {
@@ -146,12 +143,14 @@ pub fn untranscode(col: CValue, shape: &Shape) -> Vec<DValue> {
             // Inverse of transcode's Sum: untranscode each lane, then for each row pull its payload
             // from its lane at the recorded within-lane OFFSET (robust to row reordering from a
             // prior gather/merge — not a sequential cursor).
-            let (tags, offsets, variant_vals) = col.into_sum("untranscode").unwrap();
+            let (tags, variant_vals) = col.into_sum("untranscode").unwrap();
             let lane_rows: Vec<Vec<DValue>> =
                 variant_vals.into_iter().zip(lanes.iter()).map(|(v, ls)| untranscode(v, ls)).collect();
-            tags.iter()
-                .zip(&offsets)
-                .map(|(&tag, &off)| DValue::Variant(tag as u32, Box::new(lane_rows[tag][off].clone())))
+            (0..tags.len())
+                .map(|r| {
+                    let (tag, off) = (tags.tag_at(r), tags.offset_at(r));
+                    DValue::Variant(tag as u32, Box::new(lane_rows[tag][off].clone()))
+                })
                 .collect()
         }
     }
@@ -702,7 +701,7 @@ mod tests {
     /// this is what fails.
     fn hash_agrees(rows: Vec<V>, shape: Shape) {
         let col = transcode(&rows, &shape);
-        let columnar = corgi::hash(&col).into_u64("hash").unwrap();
+        let columnar = corgi::hash(&col);
         let row_wise: Vec<u64> = rows.iter().map(crate::ir::structural_hash).collect();
         assert_eq!(columnar, row_wise, "hash disagrees (shape {shape:?})");
     }
diff --git a/interactive/src/corgi/reduce.rs b/interactive/src/corgi/reduce.rs
index 85e247bd5..63e5281b2 100644
--- a/interactive/src/corgi/reduce.rs
+++ b/interactive/src/corgi/reduce.rs
@@ -57,14 +57,10 @@ fn signed_order_view(value: CValue) -> CValue {
         CValue::Prod(fields) => {
             CValue::Prod(fields.into_iter().map(signed_order_view).collect())
         }
-        CValue::Sum(tags, within, variants) => CValue::Sum(
-            tags,
-            within,
-            variants
-                .into_iter()
-                .map(signed_order_view)
-                .collect(),
-        ),
+        CValue::Sum(tags, variants) => {
+            // the lane assignment is untouched — only the payload lanes are swizzled.
+            CValue::Sum(tags, variants.into_iter().map(signed_order_view).collect())
+        }
         CValue::List(bounds, values) => {
             CValue::List(bounds, Box::new(signed_order_view(*values)))
         }
@@ -200,7 +196,7 @@ fn ids(col: &CValue) -> Vec<u64> {
     if let Some(sl) = corgi::arrange::leaf_slice(col) {
         return sl.to_vec();
     }
-    corgi::hash(col).into_u64("ids").unwrap()
+    corgi::hash(col)
 }
 
 /// Concatenate the records of the `changed` keys across a run of chunks into parallel
@@ -542,7 +538,7 @@ where
                 // next batch's `List<T>` where the two are concatenated. `gather` at no indices
                 // is the empty column of that shape.
                 let elems = gather(&self.in_vals, &elem_reps);
-                let col = CValue::List(Bounds::Offsets(bracket_ends), Box::new(elems));
+                let col = CValue::List(Bounds::offsets(bracket_ends), Box::new(elems));
                 out_ids = ids(&col);
                 self.register_vals(col, &out_ids);
             }