From 0458b435199a947a913cef885209663a411b3b58 Mon Sep 17 00:00:00 2001
From: Edward Langley <el-github@elangley.org>
Date: Wed, 23 Sep 2026 20:04:29 -0700
Subject: [PATCH] improvise-3h9w: red test, a captured edit is refused for the
 cursor's aggregate

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VdfEGXA7aJ6ftMsCc9PJze
---
 .../tests/browser_round_trip.rs               | 73 +++++++++++++++++++
 1 file changed, 73 insertions(+)

diff --git a/crates/improvise-wasm-client/tests/browser_round_trip.rs b/crates/improvise-wasm-client/tests/browser_round_trip.rs
index 40a080ab..e8db507b 100644
--- a/crates/improvise-wasm-client/tests/browser_round_trip.rs
+++ b/crates/improvise-wasm-client/tests/browser_round_trip.rs
@@ -1925,3 +1925,76 @@ fn a_retry_after_a_crossing_write_to_its_own_record_is_a_force() {
     );
     assert_eq!(region(&host, "North"), None);
 }
+
+/// `host()` with `Profit = Revenue - Cost`, so a grid with Region on None
+/// shows aggregates and a derived column, and no stored cell.
+fn host_with_profit() -> Host {
+    let mut wb = Workbook::new("Test");
+    wb.add_category("Region").unwrap();
+    wb.add_item("Region", "North").unwrap();
+    wb.add_item("Region", "South").unwrap();
+    wb.add_item("_Measure", "Revenue").unwrap();
+    wb.add_item("_Measure", "Cost").unwrap();
+    wb.model.add_formula(
+        improvise_command::formula::parse_formula("Profit = Revenue - Cost", "_Measure").unwrap(),
+    );
+    wb.active_view_mut().set_axis("Region", Axis::Row);
+    wb.active_view_mut().set_axis("_Measure", Axis::Column);
+    wb.model.set_cell(
+        CellKey::new(vec![
+            ("Region".into(), "North".into()),
+            ("_Measure".into(), "Revenue".into()),
+        ]),
+        CellValue::Number(1200.0),
+    );
+    let mut app = App::new(wb, None);
+    app.rebuild_layout();
+    Host::new(app)
+}
+
+/// improvise-3h9w: B's reframe left A's cursor on an aggregate, and Enter was
+/// refused for THAT cell instead of writing the captured one. Evidence file.
+#[test]
+fn a_captured_edit_commits_when_the_cursor_now_sits_on_an_aggregate() {
+    use improvise_command::ui::reduce::caught_up;
+    use improvise_protocol::ModelCommand;
+
+    let mut host = host_with_profit();
+    let (mut a, mut b) = (Client::new(), Client::new());
+    let (a_id, a_snap) = host.connect(10, 10);
+    let (b_id, b_snap) = host.connect(10, 10);
+    a.set_viewport(10, 10);
+    b.set_viewport(10, 10);
+    deliver(&mut a, &[a_snap]);
+    deliver(&mut b, &[b_snap]);
+    for key in ["l", "i", "4", "2"] {
+        press(&mut host, a_id, &mut a, key);
+    }
+    let region_off = ModelCommand::SetAxis {
+        view: host.app().view_name().to_string(),
+        category: "Region".into(),
+        axis: Axis::None,
+    };
+    let relayed = host.handle(
+        b_id,
+        ClientFrame::command(caught_up(host.app(), region_off)),
+    );
+    route(&relayed, (a_id, &mut a), (b_id, &mut b));
+    assert!(a.state().view.mode.is_editing(), "setup: still editing");
+    let (row, col) = a.state().view.cursor().selected;
+    assert!(
+        matches!(
+            a.state().grid.cell(row, col).and_then(|c| c.id.clone()),
+            Some(improvise_protocol::CellId::Aggregate(_))
+        ),
+        "setup: the cursor now sits on an aggregate"
+    );
+
+    press(&mut host, a_id, &mut a, "Enter");
+    assert_eq!(
+        cell(&host, "North", "Cost"),
+        Some(CellValue::Number(42.0)),
+        "the captured cell must be written: status {:?}",
+        a.state().view.status_msg
+    );
+}