Intercept keystrokes via overlay

src/ux-components/intercept-overlay/intercept-overlay.spec.js

@@ -14,4 +14,33 @@ describe("intercept-overlay.vue", () => {
         expect(wrapper.text()).toBe("");
         wrapper.unmount();
     });
+
+    describe("keyboard interception", () => {
+        test("adds a capturing keydown listener on mount and removes it on unmount", () => {
+            const addSpy = jest.spyOn(document, "addEventListener");
+            const removeSpy = jest.spyOn(document, "removeEventListener");
+
+            const wrapper = shallowMount(interceptOverlay);
+            expect(addSpy).toHaveBeenCalledWith("keydown", expect.any(Function), true);
+
+            const [, handler] = addSpy.mock.calls.find(
+                ([type, , capture]) => type === "keydown" && capture === true
+            );
+
+            wrapper.unmount();
+            expect(removeSpy).toHaveBeenCalledWith("keydown", handler, true);
+
+            addSpy.mockRestore();
+            removeSpy.mockRestore();
+        });
+
+        test("blockKey prevents default and stops immediate propagation", () => {
+            const wrapper = shallowMount(interceptOverlay);
+            const event = { preventDefault: jest.fn(), stopImmediatePropagation: jest.fn() };
+            wrapper.vm.blockKey(event);
+            expect(event.preventDefault).toHaveBeenCalled();
+            expect(event.stopImmediatePropagation).toHaveBeenCalled();
+            wrapper.unmount();
+        });
+    });
 });

src/ux-components/intercept-overlay/intercept-overlay.vue

@@ -1,10 +1,22 @@
 <template>
-    <div class="intercept-overlay" aria-hidden="true"></div>
+    <div class="intercept-overlay" aria-hidden="true" @keydown.capture="blockKey"></div>
 </template>
 
 <script>
 export default {
     name: "intercept-overlay",
+    mounted() {
+        document.addEventListener("keydown", this.blockKey, true);
+    },
+    beforeUnmount() {
+        document.removeEventListener("keydown", this.blockKey, true);
+    },
+    methods: {
+        blockKey(event) {
+            event.preventDefault();
+            event.stopImmediatePropagation();
+        },
+    },
 };
 </script>