diff --git a/context/test-evidence/command.md b/context/test-evidence/command.md
index c042f940..fff91837 100644
--- a/context/test-evidence/command.md
+++ b/context/test-evidence/command.md
@@ -227,6 +227,14 @@ checked by adding a `probe_field` to `Model` and to `Model::new`. The build then
 failed with `E0027: pattern does not mention field probe_field` at the `Debug`
 impl, and nowhere else.
 
+**`Model.measure_agg` needed the same treatment (improvise-m6op).** `Model`'s
+`Debug` sorts `measure_agg` through a `BTreeMap`, but the fixture's
+`measure_agg` was empty, so nothing saw the sort. With the sort replaced by the
+raw `HashMap` (`.field("measure_agg", &measure_agg)`), this test stayed green in
+3 of 3 runs. The fixture now carries four entries: `Revenue` Avg, `Cost` Min,
+`Units` Max and `Orders` Count. Under the same injection it is red in 3 of 3
+runs, and it is green with the sort restored.
+
 ### a_stale_wire_model_command_cannot_be_applied
 
 A wire `Command::Model` cannot reach the document without its basis being checked
diff --git a/crates/improvise-command/src/ui/reduce.rs b/crates/improvise-command/src/ui/reduce.rs
index a598f68b..4cbf2fe6 100644
--- a/crates/improvise-command/src/ui/reduce.rs
+++ b/crates/improvise-command/src/ui/reduce.rs
@@ -959,6 +959,16 @@ pub(crate) mod tests {
                 ]);
                 wb.model.set_cell(key, CellValue::Number(n as f64 + 1.0));
             }
+            // Several entries, so two instances' HashMaps can disagree on order (improvise-m6op).
+            use crate::formula::AggFunc;
+            for (measure, agg) in [
+                ("Revenue", AggFunc::Avg),
+                ("Cost", AggFunc::Min),
+                ("Units", AggFunc::Max),
+                ("Orders", AggFunc::Count),
+            ] {
+                wb.model.measure_agg.insert(measure.into(), agg);
+            }
             let view = wb.active_view_mut();
             view.set_axis("Region", Axis::Row);
             view.set_axis("Month", Axis::Column);