diff --git a/crates/ui-egui/src/ribbon.rs b/crates/ui-egui/src/ribbon.rs
index 45856565f..ab9cc311d 100644
--- a/crates/ui-egui/src/ribbon.rs
+++ b/crates/ui-egui/src/ribbon.rs
@@ -74,15 +74,23 @@ pub fn title_bar(app: &mut SheetApp, ui: &mut Ui) {
             {
                 app.run_or_alert("file.save", json!({}));
             }
-            let can_undo = app.session.active().is_some_and(|d| !d.undo.is_empty());
-            let can_redo = app.session.active().is_some_and(|d| !d.redo.is_empty());
-            if icon_button(ui, Icon::Undo, if can_undo { t.text_dim } else { t.text_disabled }, "Undo", vec2(26.0, ch)).clicked() && can_undo {
+            // The commands' own availability: there must be a step, and no undo group may be open on
+            // the document (an action that spans several calls is still running).
+            let can_undo = gridcraft_engine::cmd::can_undo(&app.session).is_ok();
+            let can_redo = gridcraft_engine::cmd::can_redo(&app.session).is_ok();
+            // Named and marked enabled or not for assistive technology (and the UI tests).
+            let undo = icon_button(ui, Icon::Undo, if can_undo { t.text_dim } else { t.text_disabled }, "Undo", vec2(26.0, ch));
+            undo.widget_info(|| egui::WidgetInfo::labeled(egui::WidgetType::Button, can_undo, "Undo"));
+            if undo.clicked() && can_undo {
                 app.run_or_alert("edit.undo", json!({}));
             }
             let undo_list = icon_button(ui, Icon::Chevron, t.text_dim, "Undo list", vec2(14.0, ch));
             egui::Popup::menu(&undo_list).show(|ui| {
-                let labels: Vec<String> =
-                    app.session.active().map(|d| d.undo.iter().rev().take(20).map(|e| e.label.clone()).collect()).unwrap_or_default();
+                let labels: Vec<String> = if can_undo {
+                    app.session.active().map(|d| d.undo.iter().rev().take(20).map(|e| e.label.clone()).collect()).unwrap_or_default()
+                } else {
+                    Vec::new()
+                };
                 if labels.is_empty() {
                     ui.label("Can't Undo");
                 }
@@ -92,7 +100,9 @@ pub fn title_bar(app: &mut SheetApp, ui: &mut Ui) {
                     }
                 }
             });
-            if icon_button(ui, Icon::Redo, if can_redo { t.text_dim } else { t.text_disabled }, "Redo", vec2(26.0, ch)).clicked() && can_redo {
+            let redo = icon_button(ui, Icon::Redo, if can_redo { t.text_dim } else { t.text_disabled }, "Redo", vec2(26.0, ch));
+            redo.widget_info(|| egui::WidgetInfo::labeled(egui::WidgetType::Button, can_redo, "Redo"));
+            if redo.clicked() && can_redo {
                 app.run_or_alert("edit.redo", json!({}));
             }
             let more = icon_button(ui, Icon::More, t.text_dim, "More commands", vec2(26.0, ch));
diff --git a/crates/ui-egui/tests/it/main.rs b/crates/ui-egui/tests/it/main.rs
index fc00fb520..b9725aed0 100644
--- a/crates/ui-egui/tests/it/main.rs
+++ b/crates/ui-egui/tests/it/main.rs
@@ -85,6 +85,7 @@ mod touch_pan;
 mod trace_navigation;
 mod translated_form_fields;
 mod ui_clock;
+mod undo_while_grouping;
 mod validation_alert;
 mod validation_input_message;
 mod wheel_zoom;
diff --git a/crates/ui-egui/tests/it/undo_while_grouping.rs b/crates/ui-egui/tests/it/undo_while_grouping.rs
new file mode 100644
index 000000000..fdc98ebf9
--- /dev/null
+++ b/crates/ui-egui/tests/it/undo_while_grouping.rs
@@ -0,0 +1,57 @@
+//! Undo and Redo on the Quick Access Toolbar follow the commands' own availability: while an undo
+//! group is open on the document (an action that spans several calls is still running), both
+//! buttons are off, and a click neither runs the command nor raises its refusal.
+
+use egui_kittest::kittest::{NodeT as _, Queryable as _};
+use gridcraft_engine::Session;
+use gridcraft_ui_egui::SheetApp;
+use serde_json::json;
+
+type Harness = egui_kittest::Harness<'static, SheetApp>;
+
+fn harness() -> Harness {
+    let mut s = Session::new();
+    s.new_workbook();
+    s.execute("cell.set", json!({"cell": "A1", "input": "1"})).unwrap();
+    s.execute("cell.set", json!({"cell": "A1", "input": "2"})).unwrap();
+    s.execute("edit.undo", json!({})).unwrap();
+    let mut h = egui_kittest::Harness::builder().with_size(egui::vec2(1200.0, 800.0)).build_ui_state(
+        |ui, app: &mut SheetApp| {
+            app.logic(ui.ctx());
+            app.ui(ui);
+        },
+        SheetApp::new(s, Default::default()),
+    );
+    h.run_steps(4);
+    h
+}
+
+fn history(h: &Harness) -> (usize, usize) {
+    let d = h.state().session.active().unwrap();
+    (d.undo.len(), d.redo.len())
+}
+
+#[test]
+fn undo_and_redo_wait_while_an_undo_group_is_open() {
+    let mut h = harness();
+    assert_eq!(history(&h), (1, 1));
+    let token = h.state_mut().session.group_begin("Long action").unwrap();
+    h.run_steps(2);
+    for button in ["Undo", "Redo"] {
+        assert!(h.get_by_label(button).accesskit_node().is_disabled(), "{button} is off while the group is open");
+        h.get_by_label(button).click();
+        h.run_steps(2);
+        assert!(h.state().message.is_none(), "{button}: no refusal is raised while the group is open");
+        assert_eq!(history(&h), (1, 1), "{button}: the history is as it was");
+    }
+    h.state_mut().session.group_end(token).unwrap();
+    h.run_steps(2);
+    assert!(!h.get_by_label("Undo").accesskit_node().is_disabled() && !h.get_by_label("Redo").accesskit_node().is_disabled());
+    // With the group ended, the buttons work again.
+    h.get_by_label("Undo").click();
+    h.run_steps(2);
+    assert_eq!(history(&h), (0, 2));
+    h.get_by_label("Redo").click();
+    h.run_steps(2);
+    assert_eq!(history(&h), (1, 1));
+}