diff --git a/crates/improvise-command/src/command/cmd/determinism.rs b/crates/improvise-command/src/command/cmd/determinism.rs
index 66a0a223..fd978aff 100644
--- a/crates/improvise-command/src/command/cmd/determinism.rs
+++ b/crates/improvise-command/src/command/cmd/determinism.rs
@@ -61,13 +61,12 @@ fn one_coordinate_drills(model: &Model) -> Vec<Vec<String>> {
     drills
 }
 
-/// Records a compared drill's own effects freeze in a fresh `App`, counted only when
-/// the drill narrowed the store: a whole-store drill never reads the index.
-fn records_narrowed(effects: Vec<Box<dyn Effect>>) -> usize {
-    let mut app = fixture();
-    let store = app.model_state.workbook.model.data.live_records().count();
-    app.apply_effects(effects);
-    let frozen = app.drill_state.map_or(0, |drill| drill.records.len());
+/// Records a compared drill's own effects freeze in `scratch`, counted only when the
+/// drill narrowed the store: a whole-store drill never reads the index.
+fn records_narrowed(scratch: &mut App, effects: Vec<Box<dyn Effect>>) -> usize {
+    let store = scratch.model_state.workbook.model.data.live_records().count();
+    scratch.apply_effects(effects);
+    let frozen = scratch.drill_state.as_ref().map_or(0, |drill| drill.records.len());
     if frozen < store { frozen } else { 0 }
 }
 
@@ -116,6 +115,7 @@ fn compare(a: &CmdContext, others: &[CmdContext]) -> Comparison {
     let drill = DrillIntoCell {
         key: CellKey::new(vec![]),
     };
+    let mut scratch = fixture();
     for name in a.registry.names().collect::<Vec<_>>() {
         let before = found.compared;
         for args in &candidates {
@@ -124,7 +124,7 @@ fn compare(a: &CmdContext, others: &[CmdContext]) -> Comparison {
             };
             let left = format!("{effects:?}");
             if name == drill.name() {
-                found.widest_drill = found.widest_drill.max(records_narrowed(effects));
+                found.widest_drill = found.widest_drill.max(records_narrowed(&mut scratch, effects));
             }
             found.compared += 1;
             for b in others {